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Zhang X, Hu Z, Liu YC. Fast Generation of GHZ-like States Using Collective-Spin XYZ Model. PHYSICAL REVIEW LETTERS 2024; 132:113402. [PMID: 38563940 DOI: 10.1103/physrevlett.132.113402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/14/2024] [Indexed: 04/04/2024]
Abstract
The Greenberger-Horne-Zeilinger (GHZ) state is a key resource for quantum information processing and quantum metrology. The atomic GHZ state can be generated by one-axis twisting (OAT) interaction H_{OAT}=χJ_{z}^{2} with χ the interaction strength, but it requires a long evolution time χt=π/2 and is thus seriously influenced by decoherence and losses. Here we propose a three-body collective-spin XYZ model which creates a GHZ-like state in a very short timescale χt∼lnN/N for N particles. We show that this model can be effectively produced by applying Floquet driving to an original OAT Hamiltonian. Compared with the ideal GHZ state, the GHZ-like state generated using our model can maintain similar metrological properties reaching the Heisenberg-limited scaling, and it shows better robustness to decoherence and particle losses. This Letter opens the avenue for generating GHZ-like states with a large particle number, which holds great potential for the study of macroscopic quantum effects and for applications in quantum metrology and quantum information.
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Affiliation(s)
- Xuanchen Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zhiyao Hu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yong-Chun Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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2
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Kalaga JK, Kowalewska-Kudłaszyk A, Leoński W, Peřina J. Legget-Garg inequality for a two-mode entangled bosonic system. OPTICS EXPRESS 2024; 32:9946-9957. [PMID: 38571218 DOI: 10.1364/oe.513855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 02/08/2024] [Indexed: 04/05/2024]
Abstract
We discuss a model of two nonlinear quantum oscillators mutually coupled by linear interaction and continuously driven by external coherent excitation. For such a system, we analyze temporal correlations. We examine the violation of the Leggett-Garg inequality analysing various scenarios of measurements. These scenarios are based on the projection onto different Bell states. We show that the possibility of violation of the Leggett-Garg inequalities is associated with the use of different projectors.
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3
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Viotti L, Lombardo FC, Villar PI. Geometric Phase of a Transmon in a Dissipative Quantum Circuit. ENTROPY (BASEL, SWITZERLAND) 2024; 26:89. [PMID: 38275497 PMCID: PMC10814483 DOI: 10.3390/e26010089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
Superconducting circuits reveal themselves as promising physical devices with multiple uses. Within those uses, the fundamental concept of the geometric phase accumulated by the state of a system shows up recurrently, as, for example, in the construction of geometric gates. Given this framework, we study the geometric phases acquired by a paradigmatic setup: a transmon coupled to a superconductor resonating cavity. We do so both for the case in which the evolution is unitary and when it is subjected to dissipative effects. These models offer a comprehensive quantum description of an anharmonic system interacting with a single mode of the electromagnetic field within a perfect or dissipative cavity, respectively. In the dissipative model, the non-unitary effects arise from dephasing, relaxation, and decay of the transmon coupled to its environment. Our approach enables a comparison of the geometric phases obtained in these models, leading to a thorough understanding of the corrections introduced by the presence of the environment.
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Affiliation(s)
- Ludmila Viotti
- The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
| | - Fernando C. Lombardo
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
| | - Paula I. Villar
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
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4
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Matarèse BFE, Rusin A, Seymour C, Mothersill C. Quantum Biology and the Potential Role of Entanglement and Tunneling in Non-Targeted Effects of Ionizing Radiation: A Review and Proposed Model. Int J Mol Sci 2023; 24:16464. [PMID: 38003655 PMCID: PMC10671017 DOI: 10.3390/ijms242216464] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/01/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
It is well established that cells, tissues, and organisms exposed to low doses of ionizing radiation can induce effects in non-irradiated neighbors (non-targeted effects or NTE), but the mechanisms remain unclear. This is especially true of the initial steps leading to the release of signaling molecules contained in exosomes. Voltage-gated ion channels, photon emissions, and calcium fluxes are all involved but the precise sequence of events is not yet known. We identified what may be a quantum entanglement type of effect and this prompted us to consider whether aspects of quantum biology such as tunneling and entanglement may underlie the initial events leading to NTE. We review the field where it may be relevant to ionizing radiation processes. These include NTE, low-dose hyper-radiosensitivity, hormesis, and the adaptive response. Finally, we present a possible quantum biological-based model for NTE.
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Affiliation(s)
- Bruno F. E. Matarèse
- Department of Haematology, University of Cambridge, Cambridge CB2 1TN, UK;
- Department of Physics, University of Cambridge, Cambridge CB2 1TN, UK
| | - Andrej Rusin
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
| | - Colin Seymour
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
| | - Carmel Mothersill
- Department of Biology, McMaster University, Hamilton, ON L8S 4L8, Canada; (A.R.); (C.S.)
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5
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Liu FM, Wang C, Chen MC, Chen H, Li SW, Shang ZX, Ying C, Wang JW, Huo YH, Peng CZ, Zhu X, Lu CY, Pan JW. Quantum computer-aided design for advanced superconducting qubit: Plasmonium. Sci Bull (Beijing) 2023; 68:1625-1631. [PMID: 37453825 DOI: 10.1016/j.scib.2023.06.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/14/2023] [Accepted: 06/25/2023] [Indexed: 07/18/2023]
Abstract
Complex quantum electronic circuits can be used to design noise-protected qubits, but their complexity may exceed the capabilities of classical simulation. In such cases, quantum computers are necessary for efficient simulation. In this work, we demonstrate the use of variational quantum computing on a transmon-based quantum processor to simulate a superconducting quantum electronic circuit and design a new type of qubit called "Plasmonium", which operates in the plasmon-transition regime. The fabricated Plasmonium qubits show a high two-qubit gate fidelity of 99.58(3)%, as well as a smaller physical size and larger anharmonicity compared to transmon qubits. These properties make Plasmonium a promising candidate for scaling up multi-qubit devices. Our results demonstrate the potential of using quantum computers to aid in the design of advanced quantum processors.
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Affiliation(s)
- Feng-Ming Liu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Can Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Ming-Cheng Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
| | - He Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Shao-Wei Li
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Zhong-Xia Shang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Chong Ying
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Jian-Wen Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Yong-Heng Huo
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Cheng-Zhi Peng
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Xiaobo Zhu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Chao-Yang Lu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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6
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Ghasemian E. Dissipative dynamics of optomagnonic nonclassical features via anti-Stokes optical pulses: squeezing, blockade, anti-correlation, and entanglement. Sci Rep 2023; 13:12757. [PMID: 37550430 PMCID: PMC10406899 DOI: 10.1038/s41598-023-39822-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/31/2023] [Indexed: 08/09/2023] Open
Abstract
We propose a feasible experimental model to investigate the generation and characterization of nonclassical states in a cavity optomagnonic system consisting of a ferromagnetic YIG sphere that simultaneously supports both the magnon mode and two whispering gallery modes of optical photons. The photons undergo the magnon-induced Brillouin light scattering, which is a well-established tool for the cavity-assisted manipulations of magnons as well as magnon spintronics. At first, we derive the desired interaction Hamiltonian under the influence of the anti-Stokes scattering process and then proceed to analyze the dynamical evolution of quantum statistics of photons and magnons as well as their intermodal entanglement. The results show that both photons and magnons generally acquire some nonclassical features, e.g., the strong antibunching and anti-correlation. Interestingly, the system may experience the perfect photon and magnon blockade phenomena, simultaneously. Besides, the nonclassical features may be protected against the unwanted environmental effects for a relatively long time, especially, in the weak driving field regime and when the system is initiated with a small number of particles. However, it should be noted that some fast quantum-classical transitions may occur in-between. Although the unwanted dissipative effects plague the nonclassical features, we show that this system can be adopted to prepare optomagnonic entangled states. The generation of entangled states depends on the initial state of the system and the interaction regime. The intermodal photon-magnon entanglement may be generated and pronounced, especially, if the system is initialized with low intensity even Schrödinger cat state in the strong coupling regime. The cavity-assisted manipulation of magnons is a unique and flexible mechanism that allows an interesting test bed for investigating the interdisciplinary contexts involving quantum optics and spintronics. Moreover, such a hybrid optomagnonic system may be used to design both on-demand single-photon and single-magnon sources and may find potential applications in quantum information processing.
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Affiliation(s)
- E Ghasemian
- Department of Electrical Engineering, Faculty of Intelligent Systems Engineering and Data Science, Persian Gulf University, Bushehr, Iran.
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7
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Hassani F, Peruzzo M, Kapoor LN, Trioni A, Zemlicka M, Fink JM. Inductively shunted transmons exhibit noise insensitive plasmon states and a fluxon decay exceeding 3 hours. Nat Commun 2023; 14:3968. [PMID: 37407570 PMCID: PMC10323121 DOI: 10.1038/s41467-023-39656-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
Currently available quantum processors are dominated by noise, which severely limits their applicability and motivates the search for new physical qubit encodings. In this work, we introduce the inductively shunted transmon, a weakly flux-tunable superconducting qubit that offers charge offset protection for all levels and a 20-fold reduction in flux dispersion compared to the state-of-the-art resulting in a constant coherence over a full flux quantum. The parabolic confinement provided by the inductive shunt as well as the linearity of the geometric superinductor facilitates a high-power readout that resolves quantum jumps with a fidelity and QND-ness of >90% and without the need for a Josephson parametric amplifier. Moreover, the device reveals quantum tunneling physics between the two prepared fluxon ground states with a measured average decay time of up to 3.5 h. In the future, fast time-domain control of the transition matrix elements could offer a new path forward to also achieve full qubit control in the decay-protected fluxon basis.
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Affiliation(s)
- F Hassani
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
| | - M Peruzzo
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - L N Kapoor
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - A Trioni
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - M Zemlicka
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - J M Fink
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
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8
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Ghasemi F, Tirandaz A. Environment assisted quantum model for studying RNA-DNA-error correlation created due to the base tautomery. Sci Rep 2023; 13:10788. [PMID: 37402822 PMCID: PMC10319750 DOI: 10.1038/s41598-023-38019-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 06/30/2023] [Indexed: 07/06/2023] Open
Abstract
The adaptive mutation phenomenon has been drawing the attention of biologists for several decades in evolutionist community. In this study, we propose a quantum mechanical model of adaptive mutation based on the implications of the theory of open quantum systems. We survey a new framework that explain how random point mutations can be stabilized and directed to be adapted with the stresses introduced by the environments according to the microscopic rules dictated by constraints of quantum mechanics. We consider a pair of entangled qubits consist of DNA and mRNA pair, each coupled to a distinct reservoir for analyzing the spreed of entanglement using time-dependent perturbation theory. The reservoirs are physical demonstrations of the cytoplasm and nucleoplasm and surrounding environments of mRNA and DNA, respectively. Our predictions confirm the role of the environmental-assisted quantum progression of adaptive mutations. Computing the concurrence as a measure that determines to what extent the bipartite DNA-mRNA can be correlated through entanglement, is given. Preventing the entanglement loss is crucial for controlling unfavorable point mutations under environmental influences. We explore which physical parameters may affect the preservation of entanglement between DNA and mRNA pair systems, despite the destructive role of interaction with the environments.
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Affiliation(s)
- Fatemeh Ghasemi
- Department of Energy Engineering, Sharif University of Technology, P.O. Box 11365-9516, Tehran, Iran.
| | - Arash Tirandaz
- Department of Chemistry, Bu-Ali Sina University, Hamedan, Iran.
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9
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Bild M, Fadel M, Yang Y, von Lüpke U, Martin P, Bruno A, Chu Y. Schrödinger cat states of a 16-microgram mechanical oscillator. Science 2023; 380:274-278. [PMID: 37079693 DOI: 10.1126/science.adf7553] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
According to quantum mechanics, a physical system can be in any linear superposition of its possible states. Although the validity of this principle is routinely validated for microscopic systems, it is still unclear why we do not observe macroscopic objects to be in superpositions of states that can be distinguished by some classical property. Here we demonstrate the preparation of a mechanical resonator in Schrödinger cat states of motion, where the ∼1017 constituent atoms are in a superposition of two opposite-phase oscillations. We control the size and phase of the superpositions and investigate their decoherence dynamics. Our results offer the possibility of exploring the boundary between the quantum and classical worlds and may find applications in continuous-variable quantum information processing and metrology with mechanical resonators.
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Affiliation(s)
- Marius Bild
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Matteo Fadel
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Yu Yang
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Uwe von Lüpke
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Phillip Martin
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Alessandro Bruno
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
| | - Yiwen Chu
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
- Quantum Center, ETH Zürich, 8093 Zürich, Switzerland
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10
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A microwave scattering spectral method to detect the nanomechanical vibrations embedded in a superconducting qubit. Sci Rep 2023; 13:4340. [PMID: 36928211 PMCID: PMC10020484 DOI: 10.1038/s41598-023-30914-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
Nanomechanical resonators (NMRs), as the quantum mechanical sensing probers, have played the important roles for various high-precision quantum measurements. Differing from the previous emission spectral probes (i.e., the NMR modified the atomic emission), in this paper we propose an alternative approach, i.e., by probing the scattering spectra of the quantum mechanical prober coupled to the driving microwaves, to characterize the physical features of the NMR embedded in a rf-SQUID based superconducting qubit. It is shown that, from the observed specifical frequency points in the spectra, i.e., either the dips or the peaks, the vibrational features (i.e., they are classical vibration or quantum mechanical one) and the physical parameters (typically such as the vibrational frequency and displacements) of the NMR can be determined effectively. The proposal is feasible with the current technique and should be useful to design the desired NMRs for various quantum metrological applications.
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11
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Peculiarities of Electron Wave Packet Dynamics in Planar Nanostructures in the Presence of Magnetic and Electric Fields. Symmetry (Basel) 2022. [DOI: 10.3390/sym14102215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Currently, spatially localized electron densities and currents are considered to be candidates for use in the encoding of quantum information. For this reason, the control of their temporal dynamics is an important task. In this work, the spatiotemporal evolution of an electron wave packet in planar nanostructure in the presence of transverse magnetic and lateral electric fields is investigated by direct analytical solution of the non-stationary Schrödinger equation. Methods to control and manage the dynamics of the spatially localized electron density distribution are developed. The production of photon-like quantum states of electrons opens up opportunities for applications similar to quantum optical and quantum information technologies but implemented with charge carriers. Quantum control of the trajectory of the electron wave packet, accompanied by dramatic suppression of its spreading, is demonstrated. This study discovered methods to manage spatially localized electron behavior in a nanostructure that allows a controllable charge quantum transfer and gives rise to new prospects for quantum nanoelectronics technology.
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12
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Satpathi U, Ray S, Vardi A. Chaos-assisted many-body tunnelling. Phys Rev E 2022; 106:L042204. [PMID: 36397523 DOI: 10.1103/physreve.106.l042204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/28/2022] [Indexed: 06/16/2023]
Abstract
We study the interplay of chaos and tunneling between two weakly coupled Bose-Josephson junctions. The classical phase space of the composite system has a mixed structure including quasi-integrable self-trapping islands for particles and excitations, separated by a chaotic sea. We show that the many-body dynamical tunneling gap between macroscopic Schrödinger cat states supported by these islands is chaos-enhanced. The many-body tunneling rate fluctuates over several orders of magnitude with small variations of the system parameters or the particle number.
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Affiliation(s)
- Urbashi Satpathi
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Sayak Ray
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Nußallee 12, 53115 Bonn, Germany
| | - Amichay Vardi
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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13
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Stolyarov VS, Ruzhitskiy V, Hovhannisyan RA, Grebenchuk S, Shishkin AG, Skryabina OV, Golovchanskiy IA, Golubov AA, Klenov NV, Soloviev II, Kupriyanov MY, Andriyash A, Roditchev D. Revealing Josephson Vortex Dynamics in Proximity Junctions below Critical Current. NANO LETTERS 2022; 22:5715-5722. [PMID: 35820103 DOI: 10.1021/acs.nanolett.2c00647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles (Andreev, A. Sov. Phys. JETP 1965, 20, 1490) which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (magnetic force microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements.
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Affiliation(s)
- Vasily S Stolyarov
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Vsevolod Ruzhitskiy
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Razmik A Hovhannisyan
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Sergey Grebenchuk
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Andrey G Shishkin
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Olga V Skryabina
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Institute of Solid State Physics RAS, 142432 Chernogolovka, Russia
| | - Igor A Golovchanskiy
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Alexander A Golubov
- Faculty of Science and Technology, MESA+ Institute of Nanotechnology, 7500 AE Enschede, The Netherlands
| | - Nikolay V Klenov
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor I Soloviev
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Mikhail Yu Kupriyanov
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | | | - Dimitri Roditchev
- LPEM, ESPCI Paris, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Universite, CNRS, LPEM, 75005 Paris, France
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14
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Gidopoulos N. Enhanced electron-phonon coupling near an electronic quantum phase transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:14LT01. [PMID: 35062005 DOI: 10.1088/1361-648x/ac4dbe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
I construct a simple model to demonstrate that when the many-electron quantum state of a material is near a quantum phase transition and the vibrational motion of a phonon explores the potential energy surface near the transition point, then an impenetrable barrier appears at the potential energy surface which restricts the phonon from crossing the transition point and abnormally increases the phonon frequency. The ensuing anomalous enhancement of the electron phonon coupling is general and independent of the specific nature of the electronic quantum phase transition. Understanding and modelling this strong electron-phonon coupling may potentially lead to the design of phonon superconductors with high critical temperatures by choosing their parameters appropriately near an electronic quantum phase transition.
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Affiliation(s)
- Nikitas Gidopoulos
- Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
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15
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Meskers SCJ. Circular Polarization of Luminescence as a Tool To Study Molecular Dynamical Processes. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100154] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Stefan C. J. Meskers
- Molecular Materials and Nanosystems and Institute for Complex Molecular Systems Eindhoven University of Technology P.O. box 513 (STW 4.37) NL 5600 MB Eindhoven Netherlands
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16
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Ham BS. Experimental demonstrations of unconditional security in a purely classical regime. Sci Rep 2021; 11:4149. [PMID: 33603110 PMCID: PMC7892578 DOI: 10.1038/s41598-021-83724-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 02/05/2021] [Indexed: 11/12/2022] Open
Abstract
So far, unconditional security in key distribution processes has been confined to quantum key distribution (QKD) protocols based on the no-cloning theorem of nonorthogonal bases. Recently, a completely different approach, the unconditionally secured classical key distribution (USCKD), has been proposed for unconditional security in the purely classical regime. Unlike QKD, both classical channels and orthogonal bases are key ingredients in USCKD, where unconditional security is provided by deterministic randomness via path superposition-based reversible unitary transformations in a coupled Mach-Zehnder interferometer. Here, the first experimental demonstration of the USCKD protocol is presented.
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Affiliation(s)
- Byoung S Ham
- Center for Photon Information Processing, School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 123 Chumdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea.
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17
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Park S, Metzger C, Tosi L, Goffman MF, Urbina C, Pothier H, Yeyati AL. From Adiabatic to Dispersive Readout of Quantum Circuits. PHYSICAL REVIEW LETTERS 2020; 125:077701. [PMID: 32857526 DOI: 10.1103/physrevlett.125.077701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Spectral properties of a quantum circuit are efficiently read out by monitoring the resonance frequency shift it induces in a microwave resonator coupled to it. When the two systems are strongly detuned, theory attributes the shift to an effective resonator capacitance or inductance that depends on the quantum circuit state. At small detuning, the shift arises from the exchange of virtual photons, as described by the Jaynes-Cummings model. Here we present a theory bridging these two limits and illustrate, with several examples, its necessity for a general description of quantum circuits readout.
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Affiliation(s)
- Sunghun Park
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - C Metzger
- Quantronics group, Service de Physique de l'État Condensé (CNRS, UMR 3680), IRAMIS, CEA-Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - L Tosi
- Quantronics group, Service de Physique de l'État Condensé (CNRS, UMR 3680), IRAMIS, CEA-Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
- Centro Atómico Bariloche and Instituto Balseiro, CNEA, CONICET, 8400 San Carlos de Bariloche, Río Negro, Argentina
| | - M F Goffman
- Quantronics group, Service de Physique de l'État Condensé (CNRS, UMR 3680), IRAMIS, CEA-Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - C Urbina
- Quantronics group, Service de Physique de l'État Condensé (CNRS, UMR 3680), IRAMIS, CEA-Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - H Pothier
- Quantronics group, Service de Physique de l'État Condensé (CNRS, UMR 3680), IRAMIS, CEA-Saclay, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - A Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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18
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Gupta S, Kutana A, Yakobson BI. Heterobilayers of 2D materials as a platform for excitonic superfluidity. Nat Commun 2020; 11:2989. [PMID: 32533022 PMCID: PMC7293212 DOI: 10.1038/s41467-020-16737-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/13/2020] [Indexed: 11/12/2022] Open
Abstract
Excitonic condensate has been long-sought within bulk indirect-gap semiconductors, quantum wells, and 2D material layers, all tried as carrying media. Here, we propose intrinsically stable 2D semiconductor heterostructures with doubly-indirect overlapping bands as optimal platforms for excitonic condensation. After screening hundreds of 2D materials, we identify candidates where spontaneous excitonic condensation mediated by purely electronic interaction should occur, and hetero-pairs Sb2Te2Se/BiTeCl, Hf2N2I2/Zr2N2Cl2, and LiAlTe2/BiTeI emerge promising. Unlike monolayers, where excitonic condensation is hampered by Peierls instability, or other bilayers, where doping by applied voltage is required, rendering them essentially non-equilibrium systems, the chemically-specific heterostructures predicted here are lattice-matched, show no detrimental electronic instability, and display broken type-III gap, thus offering optimal carrier density without any gate voltages, in true-equilibrium. Predicted materials can be used to access different parts of electron-hole phase diagram, including BEC-BCS crossover, enabling tantalizing applications in superfluid transport, Josephson-like tunneling, and dissipationless charge counterflow.
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Affiliation(s)
- Sunny Gupta
- Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Alex Kutana
- Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA
| | - Boris I Yakobson
- Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA.
- Department of Chemistry, Rice University, Houston, TX, 77005, USA.
- Smalley-Curl Institute for Nanoscale Science and Technology, Rice University, Houston, TX, 77005, USA.
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19
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Makhalov V, Satoor T, Evrard A, Chalopin T, Lopes R, Nascimbene S. Probing Quantum Criticality and Symmetry Breaking at the Microscopic Level. PHYSICAL REVIEW LETTERS 2019; 123:120601. [PMID: 31633983 DOI: 10.1103/physrevlett.123.120601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Indexed: 06/10/2023]
Abstract
We report on an experimental study of the Lipkin-Meshkov-Glick model of quantum spins interacting at infinite range in a transverse magnetic field, which exhibits a ferromagnetic phase transition in the thermodynamic limit. We use dysprosium atoms of electronic spin J=8, subjected to a quadratic Zeeman light shift, to simulate 2J=16 interacting spins 1/2. We probe the system microscopically using single magnetic sublevel resolution, giving access to the spin projection parity, which is the collective observable characterizing the underlying Z_{2} symmetry. We measure the thermodynamic properties and dynamical response of the system, and we study the quantum critical behavior around the transition point. In the ferromagnetic phase, we achieve coherent tunneling between symmetry-broken states, and we test the link between symmetry breaking and the appearance of a finite order parameter.
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Affiliation(s)
- Vasiliy Makhalov
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Tanish Satoor
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Alexandre Evrard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Thomas Chalopin
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Raphael Lopes
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - Sylvain Nascimbene
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
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20
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Popolitova DV, Klenov NV, Soloviev II, Bakurskiy SV, Tikhonova OV. Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson "atoms". BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:1548-1558. [PMID: 31467819 PMCID: PMC6693414 DOI: 10.3762/bjnano.10.152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
A theoretical approach to the consistent full quantum description of the ultrafast population transfer and magnetization reversal in superconducting meta-atoms induced by picosecond unipolar pulses of a magnetic field is developed. A promising scheme based on the regime of stimulated Raman Λ-type transitions between qubit states via upper-lying levels is suggested in order to provide ultrafast quantum operations on the picosecond time scale. The experimental realization of a circuit-on-chip for the discussed ultrafast control is presented.
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Affiliation(s)
- Daria V Popolitova
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
| | - Nikolay V Klenov
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Moscow Technical University of Communications and Informatics (MTUCI), 111024 Moscow, Russia
| | - Igor I Soloviev
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
| | - Sergey V Bakurskiy
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
| | - Olga V Tikhonova
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
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21
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Masiello DJ, Reinhardt WP. Symmetry-Broken Many-Body Excited States of the Gaseous Atomic Double-Well Bose-Einstein Condensate. J Phys Chem A 2019; 123:1962-1967. [PMID: 30785746 DOI: 10.1021/acs.jpca.8b10583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macroscopic, many-body self-trapped and quantum superposition states of the gaseous double-well Bose-Einstein condensate (BEC) are investigated within the context of a multiconfigurational bosonic self-consistent field theory based upon underlying spatially symmetry-broken one-body wave functions. To aid in the interpretation of our results, an approximate model is constructed in the extreme Fock state limit, in which self-trapped and superposition states emerge in the many-body spectrum, striking a delicate balance between the degree of symmetry breaking, the effects of the condensate's mean field, and that of atomic correlation. It is found, in both the model and full theory, that the superposition state lies energetically below its related self-trapped counterpart even when many configurations are involved. Noticeably different spatial density profiles are associated with each type of excited state, thus providing a rigorous justification for approximate descriptions of high-lying excited states of the BEC.
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Affiliation(s)
- David J Masiello
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
| | - William P Reinhardt
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
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22
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Quantum-enhanced sensing using non-classical spin states of a highly magnetic atom. Nat Commun 2018; 9:4955. [PMID: 30470745 PMCID: PMC6251866 DOI: 10.1038/s41467-018-07433-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/26/2018] [Indexed: 11/08/2022] Open
Abstract
Coherent superposition states of a mesoscopic quantum object play a major role in our understanding of the quantum to classical boundary, as well as in quantum-enhanced metrology and computing. However, their practical realization and manipulation remains challenging, requiring a high degree of control of the system and its coupling to the environment. Here, we use dysprosium atoms-the most magnetic element in its ground state-to realize coherent superpositions between electronic spin states of opposite orientation, with a mesoscopic spin size J = 8. We drive coherent spin states to quantum superpositions using non-linear light-spin interactions, observing a series of collapses and revivals of quantum coherence. These states feature highly non-classical behavior, with a sensitivity to magnetic fields enhanced by a factor 13.9(1.1) compared to coherent spin states-close to the Heisenberg limit 2J = 16-and an intrinsic fragility to environmental noise.
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23
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Abstract
We report development and microwave characterization of rf SQUID (Superconducting QUantum Interference Device) qubits, consisting of an aluminium-based Josephson junction embedded in a superconducting loop patterned from a thin film of TiN with high kinetic inductance. Here we demonstrate that the systems can offer small physical size, high anharmonicity, and small scatter of device parameters. The work constitutes a non-tunable prototype realization of an rf SQUID qubit built on the kinetic inductance of a superconducting nanowire, proposed in Phys. Rev. Lett. 104, 027002 (2010). The hybrid devices can be utilized as tools to shed further light onto the origin of film dissipation and decoherence in phase-slip nanowire qubits, patterned entirely from disordered superconducting films.
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24
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Bose S, Home D, Mal S. Nonclassicality of the Harmonic-Oscillator Coherent State Persisting up to the Macroscopic Domain. PHYSICAL REVIEW LETTERS 2018; 120:210402. [PMID: 29883147 DOI: 10.1103/physrevlett.120.210402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 12/29/2017] [Indexed: 06/08/2023]
Abstract
Can the most "classical-like" of all quantum states, namely the Schrödinger coherent state of a harmonic oscillator, exhibit nonclassical behavior? We find that for an oscillating object initially in a coherent state, merely by observing at various instants which spatial region the object is in, the Leggett-Garg inequality (LGI) can be violated through a genuine negative result measurement, thereby repudiating the everyday notion of macrorealism. This violation thus reveals an unnoticed nonclassicality of the very state which epitomizes classicality within the quantum description. It is found that for any given mass and oscillator frequency, a significant quantum violation of LGI can be obtained by suitably choosing the initial peak momentum of the coherent state wave packet. It thus opens up potentially the simplest way (without coupling with any ancillary quantum system or using nonlinearity) for testing whether various recently engineered and sought after macroscopic oscillators, such as feedback cooled thermal trapped nanocrystals of ∼10^{6}-10^{9} amu mass, are indeed bona fide nonclassical objects.
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Affiliation(s)
- S Bose
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D Home
- CAPSS, Physics Department, Bose Institute, Salt Lake, Sector V, Kolkata 700097, India
| | - S Mal
- S.N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India
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25
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Enhancing Metastability by Dissipation and Driving in an Asymmetric Bistable Quantum System. ENTROPY 2018; 20:e20040226. [PMID: 33265317 PMCID: PMC7512741 DOI: 10.3390/e20040226] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/01/2018] [Accepted: 03/23/2018] [Indexed: 12/19/2022]
Abstract
The stabilizing effect of quantum fluctuations on the escape process and the relaxation dynamics from a quantum metastable state are investigated. Specifically, the quantum dynamics of a multilevel bistable system coupled to a bosonic Ohmic thermal bath in strong dissipation regime is analyzed. The study is performed by a non-perturbative method based on the real-time path integral approach of the Feynman-Vernon influence functional. We consider a strongly asymmetric double well potential with and without a monochromatic external driving, and with an out-of-equilibrium initial condition. In the absence of driving we observe a nonmonotonic behavior of the escape time from the metastable region, as a function both of the system-bath coupling coefficient and the temperature. This indicates a stabilizing effect of the quantum fluctuations. In the presence of driving our findings indicate that, as the coupling coefficient γ increases, the escape time, initially controlled by the external driving, shows resonant peaks and dips, becoming frequency-independent for higher γ values. Moreover, the escape time from the metastable state displays a nonmonotonic behavior as a function of the temperature, the frequency of the driving, and the thermal-bath coupling, which indicates the presence of a quantum noise enhanced stability phenomenon. Finally, we investigate the role of different spectral densities, both in sub-Ohmic and super-Ohmic dissipation regime and for different cutoff frequencies, on the relaxation dynamics from the quantum metastable state. The results obtained indicate that, in the crossover dynamical regime characterized by damped intrawell oscillations and incoherent tunneling, the spectral properties of the thermal bath influence non-trivially the short time behavior and the time scales of the relaxation dynamics from the metastable state.
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26
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Entanglement between more than two hundred macroscopic atomic ensembles in a solid. Nat Commun 2017; 8:906. [PMID: 29030556 PMCID: PMC5640660 DOI: 10.1038/s41467-017-00897-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/03/2017] [Indexed: 11/24/2022] Open
Abstract
There are both fundamental and practical motivations for studying whether quantum entanglement can exist in macroscopic systems. However, multiparty entanglement is generally fragile and difficult to quantify. Dicke states are multiparty entangled states where a single excitation is delocalized over many systems. Building on previous work on quantum memories for photons, we create a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies. The photon is re-emitted at a well-defined time due to an interference effect analogous to multi-slit diffraction. We derive a lower bound for the number of entangled ensembles based on the contrast of the interference and the single-photon character of the input, and we experimentally demonstrate entanglement between over two hundred ensembles, each containing a billion atoms. We also illustrate the fact that each individual ensemble contains further entanglement. Multipartite entanglement is of both fundamental and practical interest, but is notoriously difficult to witness and characterise. Here, Zarkeshian et al. demonstrate multipartite entanglement in an atomic frequency comb storing a single photon in a Dicke state spread over a macroscopic ensemble.
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27
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Wendin G. Quantum information processing with superconducting circuits: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:106001. [PMID: 28682303 DOI: 10.1088/1361-6633/aa7e1a] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of quantum supremacy with fifty qubits is anticipated in just a few years. Quantum supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of superconducting devices, systems and applications. As such, the discussion of superconducting qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry.
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Affiliation(s)
- G Wendin
- Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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28
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Johnson KG, Wong-Campos JD, Neyenhuis B, Mizrahi J, Monroe C. Ultrafast creation of large Schrödinger cat states of an atom. Nat Commun 2017; 8:697. [PMID: 28951588 PMCID: PMC5614983 DOI: 10.1038/s41467-017-00682-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 07/20/2017] [Indexed: 11/23/2022] Open
Abstract
Mesoscopic quantum superpositions, or Schrödinger cat states, are widely studied for fundamental investigations of quantum measurement and decoherence as well as applications in sensing and quantum information science. The generation and maintenance of such states relies upon a balance between efficient external coherent control of the system and sufficient isolation from the environment. Here we create a variety of cat states of a single trapped atom’s motion in a harmonic oscillator using ultrafast laser pulses. These pulses produce high fidelity impulsive forces that separate the atom into widely separated positions, without restrictions that typically limit the speed of the interaction or the size and complexity of the resulting motional superposition. This allows us to quickly generate and measure cat states larger than previously achieved in a harmonic oscillator, and create complex multi-component superposition states in atoms. Generation of mesoscopic quantum superpositions requires both reliable coherent control and isolation from the environment. Here, the authors succeed in creating a variety of cat states of a single trapped atom, mapping spin superpositions into spatial superpositions using ultrafast laser pulses.
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Affiliation(s)
- K G Johnson
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA.
| | - J D Wong-Campos
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - B Neyenhuis
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - J Mizrahi
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
| | - C Monroe
- Department of Physics, Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, 20742, USA
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29
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Dakić B, Radonjić M. Macroscopic Superpositions as Quantum Ground States. PHYSICAL REVIEW LETTERS 2017; 119:090401. [PMID: 28949556 DOI: 10.1103/physrevlett.119.090401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Indexed: 06/07/2023]
Abstract
We study the question of what kind of a macroscopic superposition can(not) naturally exist as a ground state of some gapped local many-body Hamiltonian. We derive an upper bound on the energy gap of an arbitrary physical Hamiltonian provided that its ground state is a superposition of two well-distinguishable macroscopic "semiclassical" states. For a large class of macroscopic superposition states we show that the gap vanishes in the macroscopic limit. This in turn shows that preparation of such states by simple cooling to the ground state is not experimentally feasible and requires a different strategy. Our approach is very general and can be used to rule out a variety of quantum states, some of which do not even exhibit macroscopic quantum properties. Moreover, our methods and results can be used for addressing quantum marginal related problems.
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Affiliation(s)
- Borivoje Dakić
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Milan Radonjić
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
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30
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Szańkowski P, Ramon G, Krzywda J, Kwiatkowski D, Cywiński Ł. Environmental noise spectroscopy with qubits subjected to dynamical decoupling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:333001. [PMID: 28569239 DOI: 10.1088/1361-648x/aa7648] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A qubit subjected to pure dephasing due to classical Gaussian noise can be turned into a spectrometer of this noise by utilizing its readout under properly chosen dynamical decoupling (DD) sequences to reconstruct the power spectral density of the noise. We review the theory behind this DD-based noise spectroscopy technique, paying special attention to issues that arise when the environmental noise is non-Gaussian and/or it has truly quantum properties. While we focus on the theoretical basis of the method, we connect the discussed concepts with specific experiments, and provide an overview of environmental noise models relevant for solid-state based qubits, including quantum-dot based spin qubits, superconducting qubits, and NV centers in diamond.
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Affiliation(s)
- P Szańkowski
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
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31
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Eriksson AM, Vikström A. Zero-Phase-Difference Josephson Current Based on Spontaneous Symmetry Breaking via Parametric Excitation of a Movable Superconducting Dot. PHYSICAL REVIEW LETTERS 2017; 118:197701. [PMID: 28548522 DOI: 10.1103/physrevlett.118.197701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Indexed: 06/07/2023]
Abstract
Recent advances have attracted attention to nonstandard Josephson junctions in which a supercurrent can flow despite zero phase difference between the constituent superconducting leads. Here, we propose a zero-phase-difference nanoelectromechanical junction which, in contrast to other considered systems, exhibits symmetry between leftward and rightward tunneling through the junction. We show that a supercurrent is, nevertheless, possible as a result of spontaneous symmetry breaking. In the suggested junction, the supercurrent is mediated by tunneling via a superconducting Cooper-pair box on a mechanical resonator. An alternating electric potential parametrically excites mechanical oscillations which are synchronized with charge oscillations of the box. This leads to coherent transfer of Cooper pairs through the junction. The direction of the supercurrent is a result of spontaneous symmetry breaking and thus it can be reversed without changing the parameters.
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Affiliation(s)
- A M Eriksson
- Department of Physics, Chalmers University of Technology, Kemigården 1, SE-412 96 Göteborg, Sweden
| | - A Vikström
- Department of Physics, Chalmers University of Technology, Kemigården 1, SE-412 96 Göteborg, Sweden
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32
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Toughening Mechanisms in Nanolayered MAX Phase Ceramics-A Review. MATERIALS 2017; 10:ma10040366. [PMID: 28772723 PMCID: PMC5506927 DOI: 10.3390/ma10040366] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 11/25/2022]
Abstract
Advanced engineering and functional ceramics are sensitive to damage cracks, which delay the wide applications of these materials in various fields. Ceramic composites with enhanced fracture toughness may trigger a paradigm for design and application of the brittle components. This paper reviews the toughening mechanisms for the nanolayered MAX phase ceramics. The main toughening mechanisms for these ternary compounds were controlled by particle toughening, phase-transformation toughening and fiber-reinforced toughening, as well as texture toughening. Based on the various toughening mechanisms in MAX phase, models of SiC particles and fibers toughening Ti3SiC2 are established to predict and explain the toughening mechanisms. The modeling work provides insights and guidance to fabricate MAX phase-related composites with optimized microstructures in order to achieve the desired mechanical properties required for harsh application environments.
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33
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Ragole S, Taylor JM. Interacting Atomic Interferometry for Rotation Sensing Approaching the Heisenberg Limit. PHYSICAL REVIEW LETTERS 2016; 117:203002. [PMID: 27886499 DOI: 10.1103/physrevlett.117.203002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Indexed: 06/06/2023]
Abstract
Atom interferometers provide exquisite measurements of the properties of noninertial frames. While atomic interactions are typically detrimental to good sensing, efforts to harness entanglement to improve sensitivity remain tantalizing. Here we explore the role of interactions in an analogy between atomic gyroscopes and SQUIDs, motivated by recent experiments realizing ring-shaped traps for ultracold atoms. We explore the one-dimensional limit of these ring systems with a moving weak barrier, such as that provided by a blue-detuned laser beam. In this limit, we employ Luttinger liquid theory and find an analogy with the superconducting phase-slip qubit, in which the topological charge associated with persistent currents can be put into superposition. In particular, we find that strongly interacting atoms in such a system could be used for precision rotation sensing. We compare the performance of this new sensor to an equivalent noninteracting atom interferometer, and find improvements in sensitivity and bandwidth beyond the atomic shot-noise limit.
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Affiliation(s)
- Stephen Ragole
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - Jacob M Taylor
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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34
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Huang Z, Maccone L, Karim A, Macchiavello C, Chapman RJ, Peruzzo A. High-dimensional entanglement certification. Sci Rep 2016; 6:27637. [PMID: 27311935 PMCID: PMC4911610 DOI: 10.1038/srep27637] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/23/2016] [Indexed: 11/29/2022] Open
Abstract
Quantum entanglement is the ability of joint quantum systems to possess global properties (correlation among systems) even when subsystems have no definite individual property. Whilst the 2-dimensional (qubit) case is well-understood, currently, tools to characterise entanglement in high dimensions are limited. We experimentally demonstrate a new procedure for entanglement certification that is suitable for large systems, based entirely on information-theoretics. It scales more efficiently than Bell's inequality and entanglement witness. The method we developed works for arbitrarily large system dimension d and employs only two local measurements of complementary properties. This procedure can also certify whether the system is maximally entangled. We illustrate the protocol for families of bipartite states of qudits with dimension up to 32 composed of polarisation-entangled photon pairs.
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Affiliation(s)
- Zixin Huang
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- School of Physics, University of Sydney, NSW 2006, Australia
| | - Lorenzo Maccone
- Dip. Fisica and INFN Sez. Pavia, University of Pavia, via Bassi 6, I-27100 Pavia, Italy
| | - Akib Karim
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- School of Physics, University of Sydney, NSW 2006, Australia
| | - Chiara Macchiavello
- Dip. Fisica and INFN Sez. Pavia, University of Pavia, via Bassi 6, I-27100 Pavia, Italy
| | - Robert J. Chapman
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- School of Physics, University of Sydney, NSW 2006, Australia
| | - Alberto Peruzzo
- Quantum Photonics Laboratory, School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
- School of Physics, University of Sydney, NSW 2006, Australia
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35
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Liao JQ, Tian L. Macroscopic Quantum Superposition in Cavity Optomechanics. PHYSICAL REVIEW LETTERS 2016; 116:163602. [PMID: 27152802 DOI: 10.1103/physrevlett.116.163602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Indexed: 06/05/2023]
Abstract
Quantum superposition in mechanical systems is not only key evidence for macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We study systematically the generation of the Yurke-Stoler-like states in the presence of system dissipations. We also discuss the experimental implementation of this scheme.
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Affiliation(s)
- Jie-Qiao Liao
- School of Natural Sciences, University of California, Merced, California 95343, USA
| | - Lin Tian
- School of Natural Sciences, University of California, Merced, California 95343, USA
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36
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Hua M, Tao MJ, Deng FG, Lu Long G. One-step resonant controlled-phase gate on distant transmon qutrits in different 1D superconducting resonators. Sci Rep 2015; 5:14541. [PMID: 26486426 PMCID: PMC4613593 DOI: 10.1038/srep14541] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/27/2015] [Indexed: 11/09/2022] Open
Abstract
We propose a scheme to construct the controlled-phase (c-phase) gate on distant transmon qutrits hosted in different resonators inter-coupled by a connected transmon qutrit. Different from previous works for entanglement generation and information transfer on two distant qubits in a dispersive regime in the similar systems, our gate is constructed in the resonant regime with one step. The numerical simulation shows that the fidelity of our c-phase gate is 99.5% within 86.3 ns. As an interesting application of our c-phase gate, we propose an effective scheme to complete a conventional square lattice of two-dimensional surface code layout for fault-tolerant quantum computing on the distant transmon qutrits. The four-step coupling between the nearest distant transmon qutrits, small coupling strengths of the distant transmon qutrits, and the non-population on the connection transmon qutrit can reduce the interactions among different parts of the layout effectively, which makes the layout be integrated with a large scale in an easier way.
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Affiliation(s)
- Ming Hua
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Tsinghua National Laboratory for Information Science and Technology, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Ming-Jie Tao
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Fu-Guo Deng
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Gui Lu Long
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Tsinghua National Laboratory for Information Science and Technology, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
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37
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Magazzù L, Valenti D, Spagnolo B, Grifoni M. Dissipative dynamics in a quantum bistable system: crossover from weak to strong damping. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:032123. [PMID: 26465442 DOI: 10.1103/physreve.92.032123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Indexed: 06/05/2023]
Abstract
The dissipative dynamics of a quantum bistable system coupled to a Ohmic heat bath is investigated beyond the spin-boson approximation. Within the path-integral approach to quantum dissipation, we propose an approximation scheme which exploits the separation of time scales between intra- and interwell (tunneling) dynamics. The resulting generalized master equation for the populations in a space localized basis enables us to investigate a wide range of temperatures and system-environment coupling strengths. A phase diagram in the coupling-temperature space is provided to give a comprehensive account of the different dynamical regimes.
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Affiliation(s)
- Luca Magazzù
- Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, Italy
- Radiophysics Department, Lobachevsky State University of Nizhni Novgorod, Russia
| | - Davide Valenti
- Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, Italy
| | - Bernardo Spagnolo
- Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, Italy
- Radiophysics Department, Lobachevsky State University of Nizhni Novgorod, Russia
- Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Italy
| | - Milena Grifoni
- Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
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38
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Smirne A, Bassi A. Dissipative Continuous Spontaneous Localization (CSL) model. Sci Rep 2015; 5:12518. [PMID: 26243034 PMCID: PMC4525142 DOI: 10.1038/srep12518] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 06/22/2015] [Indexed: 11/09/2022] Open
Abstract
Collapse models explain the absence of quantum superpositions at the macroscopic scale, while giving practically the same predictions as quantum mechanics for microscopic systems. The Continuous Spontaneous Localization (CSL) model is the most refined and studied among collapse models. A well-known problem of this model, and of similar ones, is the steady and unlimited increase of the energy induced by the collapse noise. Here we present the dissipative version of the CSL model, which guarantees a finite energy during the entire system's evolution, thus making a crucial step toward a realistic energy-conserving collapse model. This is achieved by introducing a non-linear stochastic modification of the Schrödinger equation, which represents the action of a dissipative finite-temperature collapse noise. The possibility to introduce dissipation within collapse models in a consistent way will have relevant impact on the experimental investigations of the CSL model, and therefore also on the testability of the quantum superposition principle.
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Affiliation(s)
- Andrea Smirne
- 1] Dipartimento di Fisica, Università degli Studi di Trieste, Strada Costiera 11, I-34151 Trieste, Italy [2] Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, I-34127 Trieste, Italy
| | - Angelo Bassi
- 1] Dipartimento di Fisica, Università degli Studi di Trieste, Strada Costiera 11, I-34151 Trieste, Italy [2] Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Via Valerio 2, I-34127 Trieste, Italy
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39
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Klenov NV, Kuznetsov AV, Soloviev II, Bakurskiy SV, Tikhonova OV. Magnetic reversal dynamics of a quantum system on a picosecond timescale. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1946-56. [PMID: 26665066 PMCID: PMC4660925 DOI: 10.3762/bjnano.6.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 09/04/2015] [Indexed: 05/14/2023]
Abstract
We present our approach for a consistent, fully quantum mechanical description of the magnetization reversal process in natural and artificial atomic systems by means of short magnetic pulses. In terms of the simplest model of a two-level system with a magnetic moment, we analyze the possibility of a fast magnetization reversal on the picosecond timescale induced by oscillating or short unipolar magnetic pulses. We demonstrate the possibility of selective magnetization reversal of a superconducting flux qubit using a single flux quantum-based pulse and suggest a promising, rapid Λ-scheme for resonant implementation of this process. In addition, the magnetization reversal treatment is fulfilled within the framework of the macroscopic theory of the magnetic moment, which allows for the comparison and explanation of the quantum and classical behavior.
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Affiliation(s)
- Nikolay V Klenov
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
- Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow 124460, Russia
- Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow Region, Russia
| | - Alexey V Kuznetsov
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
| | - Igor I Soloviev
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
- Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow 124460, Russia
- Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow Region, Russia
| | - Sergey V Bakurskiy
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
| | - Olga V Tikhonova
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
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40
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Lau HW, Dutton Z, Wang T, Simon C. Proposal for the creation and optical detection of spin cat states in Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2014; 113:090401. [PMID: 25215963 DOI: 10.1103/physrevlett.113.090401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Indexed: 06/03/2023]
Abstract
We propose a method to create "spin cat states," i.e., macroscopic superpositions of coherent spin states, in Bose-Einstein condensates using the Kerr nonlinearity due to atomic collisions. Based on a detailed study of atom loss, we conclude that cat sizes of hundreds of atoms should be realistic. The existence of the spin cat states can be demonstrated by optical readout. Our analysis also includes the effects of higher-order nonlinearities, atom number fluctuations, and limited readout efficiency.
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Affiliation(s)
- Hon Wai Lau
- Institute for Quantum Science and Technology and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta, Canada
| | - Zachary Dutton
- Quantum Information Processing Group, Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
| | - Tian Wang
- Institute for Quantum Science and Technology and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta, Canada
| | - Christoph Simon
- Institute for Quantum Science and Technology and Department of Physics and Astronomy, University of Calgary, Calgary T2N 1N4, Alberta, Canada
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41
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Rombetto S, Granata C, Vettoliere A, Russo M. Multichannel system based on a high sensitivity superconductive sensor for magnetoencephalography. SENSORS (BASEL, SWITZERLAND) 2014; 14:12114-26. [PMID: 25006995 PMCID: PMC4168467 DOI: 10.3390/s140712114] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/19/2014] [Accepted: 07/02/2014] [Indexed: 11/30/2022]
Abstract
We developed a multichannel system based on superconducting quantum interference devices (SQUIDs) for magnetoencephalography measurements. Our system consists of 163 fully-integrated SQUID magnetometers, 154 channels and 9 references, and all of the operations are performed inside a magnetically-shielded room. The system exhibits a magnetic field noise spectral density of approximatively 5 fT/Hz(1=2). The presented magnetoencephalography is the first system working in a clinical environment in Italy.
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Affiliation(s)
- Sara Rombetto
- Istituto di Cibernetica "E. Caianiello", CNR, Pozzuoli, 80078 Naples, Italy.
| | - Carmine Granata
- Istituto di Cibernetica "E. Caianiello", CNR, Pozzuoli, 80078 Naples, Italy.
| | - Antonio Vettoliere
- Istituto di Cibernetica "E. Caianiello", CNR, Pozzuoli, 80078 Naples, Italy.
| | - Maurizio Russo
- Istituto di Cibernetica "E. Caianiello", CNR, Pozzuoli, 80078 Naples, Italy.
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42
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Kani A, Wanare H. Harnessing quantum superposition and interference in atomic systems. OPTICS EXPRESS 2014; 22:15305-15314. [PMID: 24977621 DOI: 10.1364/oe.22.015305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We propose resilient quantum superposition states in closed-loop multilevel system which result in myriad quantum interference phenomena. An interplay of these superposition states results in a whole gamut of atomic phenomena including coherent population trapping (CPT), electromagnetically induced transparency (EIT), electromagnetically induced absorption (EIA), amplification without inversion (AWI) and enhancement of refractive index accompanied with negligible absorption. The polarization and the phases of the fields transform the underlying superposition of the excited states leading to all these effects, where, given the macroscopic nature of these phenomena the quantum superposition states as well as the synergy between them can be ascertained. Numerical simulations for D1 transition in room temperature Rb87 atomic vapour system bear out these findings.
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43
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Das S, Dey A, Biswas S, Colacio E, Chandrasekhar V. Hydroxide-Free Cubane-Shaped Tetranuclear [Ln4] Complexes. Inorg Chem 2014; 53:3417-26. [DOI: 10.1021/ic402827b] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Sourav Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Atanu Dey
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Sourav Biswas
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Enrique Colacio
- Departamento
de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Avenida de Fuentenueva s/n, 18071 Granada, Spain
| | - Vadapalli Chandrasekhar
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
- National Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya
Marg, PO: Sainik School, Bhubaneswar - 751 005, India
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44
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Peropadre B, Zueco D, Porras D, García-Ripoll JJ. Nonequilibrium and nonperturbative dynamics of ultrastrong coupling in open lines. PHYSICAL REVIEW LETTERS 2013; 111:243602. [PMID: 24483659 DOI: 10.1103/physrevlett.111.243602] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/03/2023]
Abstract
The time and space resolved dynamics of a qubit with an Ohmic coupling to propagating 1D photons is studied, from weak coupling to the ultrastrong coupling regime. A nonperturbative study based on matrix product states shows the following results, (i) The ground state of the combined systems contains excitations of both the qubit and the surrounding bosonic field. (ii) An initially excited qubit equilibrates through spontaneous emission to a state, which under certain conditions is locally close to that ground state, both in the qubit and the field. (iii) The resonances of the combined qubit-photon system match those of the spontaneous emission process and also the predictions of the adiabatic renormalization [A. J. Leggett et al., Rev. Mod. Phys. 59, 1 (1987)]. Finally, nonperturbative ab initio calculations show that this physics can be studied using a flux qubit galvanically coupled to a superconducting transmission line.
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Affiliation(s)
- B Peropadre
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid E-28006, Spain
| | - D Zueco
- Instituto de Ciencia de Materiales de Aragón y Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza E-50009, Spain and Fundación ARAID, Paseo María Agustín 36, Zaragoza E-50004, Spain
| | - D Porras
- Facultad de CC. Físicas, Universidad Complutense de Madrid, Madrid E-28040, Spain and Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom
| | - J J García-Ripoll
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid E-28006, Spain
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45
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Ryu C, Blackburn PW, Blinova AA, Boshier MG. Experimental realization of Josephson junctions for an atom SQUID. PHYSICAL REVIEW LETTERS 2013; 111:205301. [PMID: 24289693 DOI: 10.1103/physrevlett.111.205301] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Indexed: 06/02/2023]
Abstract
We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.
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Affiliation(s)
- C Ryu
- P-21, Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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46
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Scala M, Kim MS, Morley GW, Barker PF, Bose S. Matter-wave interferometry of a levitated thermal nano-oscillator induced and probed by a spin. PHYSICAL REVIEW LETTERS 2013; 111:180403. [PMID: 24237492 DOI: 10.1103/physrevlett.111.180403] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 06/02/2023]
Abstract
We show how the interference between spatially separated states of the center of mass (c.m.) of a mesoscopic harmonic oscillator can be evidenced by coupling it to a spin and performing solely spin manipulations and measurements (Ramsey interferometry). We propose to use an optically levitated diamond bead containing a nitrogen-vacancy center spin. The nanoscale size of the bead makes the motional decoherence due to levitation negligible. The form of the spin-motion coupling ensures that the scheme works for thermal states so that moderate feedback cooling suffices. No separate control or observation of the c.m. state is required and thereby one dispenses with cavities, spatially resolved detection, and low-mass-dispersion ensembles. The controllable relative phase in the Ramsey interferometry stems from a gravitational potential difference so that it uniquely evidences coherence between states which involve the whole nanocrystal being in spatially distinct locations.
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Affiliation(s)
- M Scala
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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47
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Liu CY, Chen C, Chang CT, Shih LM. Single-hidden-layer feed-forward quantum neural network based on Grover learning. Neural Netw 2013; 45:144-50. [PMID: 23545155 DOI: 10.1016/j.neunet.2013.02.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 12/12/2012] [Accepted: 02/27/2013] [Indexed: 10/27/2022]
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48
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Dóra B, Pollmann F, Fortágh J, Zaránd G. Loschmidt echo and the many-body orthogonality catastrophe in a qubit-coupled Luttinger liquid. PHYSICAL REVIEW LETTERS 2013; 111:046402. [PMID: 23931387 DOI: 10.1103/physrevlett.111.046402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Indexed: 06/02/2023]
Abstract
We investigate the many-body generalization of the orthogonality catastrophe by studying the generalized Loschmidt echo of Luttinger liquids (LLs) after a global change of interaction. It decays exponentially with system size and exhibits universal behavior: the steady state exponent after quenching back and forth n times between 2 LLs (bang-bang protocol) is 2n times bigger than that of the adiabatic overlap and depends only on the initial and final LL parameters. These are corroborated numerically by matrix-product state based methods of the XXZ Heisenberg model. An experimental setup consisting of a hybrid system containing cold atoms and a flux qubit coupled to a Feshbach resonance is proposed to measure the Loschmidt echo using rf spectroscopy or Ramsey interferometry.
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Affiliation(s)
- Balázs Dóra
- BME-MTA Exotic Quantum Phases Research Group, Budapest University of Technology and Economics, Budapest 1521, Hungary.
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Fornieri A, Amado M, Carillo F, Dolcini F, Biasiol G, Sorba L, Pellegrini V, Giazotto F. A ballistic quantum ring Josephson interferometer. NANOTECHNOLOGY 2013; 24:245201. [PMID: 23680804 DOI: 10.1088/0957-4484/24/24/245201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report the realization of a ballistic Josephson interferometer. The interferometer is made from a quantum ring etched in a nanofabricated two-dimensional electron gas confined in an InAs-based heterostructure laterally contacted to superconducting niobium leads. The Josephson current flowing through the structure shows oscillations with h/e flux periodicity when threading the loop with a perpendicular magnetic field. This periodicity, in sharp contrast with the h/2e one observed in conventional dc superconducting quantum interference devices, confirms the ballistic nature of the device in agreement with theoretical predictions. This system paves the way for the implementation of interferometric Josephson π-junctions, and for the investigation of Majorana fermions.
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Affiliation(s)
- A Fornieri
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa, Italy
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Chandrasekhar V, Hossain S, Das S, Biswas S, Sutter JP. Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior. Inorg Chem 2013; 52:6346-53. [PMID: 23679856 DOI: 10.1021/ic302848k] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.
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