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Chu Y, Li X, Cai J. Quantum Delocalization on Correlation Landscape: The Key to Exponentially Fast Multipartite Entanglement Generation. PHYSICAL REVIEW LETTERS 2024; 133:110201. [PMID: 39332008 DOI: 10.1103/physrevlett.133.110201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 07/03/2024] [Accepted: 08/12/2024] [Indexed: 09/29/2024]
Abstract
Entanglement, a hallmark of quantum mechanics, is a vital resource for quantum technologies. Generating highly entangled multipartite states is a key goal in current quantum experiments. We unveil a novel framework for understanding entanglement generation dynamics in Hamiltonian systems by quantum delocalization of an effective operator wave function on a correlation landscape. Our framework establishes a profound connection between the exponentially fast generation of multipartite entanglement, witnessed by the quantum Fisher information, and the linearly increasing asymptotics of hopping amplitudes governing the delocalization dynamics in Krylov space. We illustrate this connection using the paradigmatic Lipkin-Meshkov-Glick model and highlight potential signatures in chaotic Feingold-Peres tops. Our results provide a transformative tool for understanding and harnessing rapid entanglement production in complex quantum systems, providing a pathway for quantum enhanced technologies by large-scale entanglement.
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2
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Yu H, Zhang X, Zhang J, Wu Z, Jiao L, Li K, Zheng W. Key Technologies in Developing Chip-Scale Hot Atomic Devices for Precision Quantum Metrology. MICROMACHINES 2024; 15:1095. [PMID: 39337757 PMCID: PMC11434288 DOI: 10.3390/mi15091095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2024] [Revised: 08/22/2024] [Accepted: 08/23/2024] [Indexed: 09/30/2024]
Abstract
Chip-scale devices harnessing the interaction between hot atomic ensembles and light are pushing the boundaries of precision measurement techniques into unprecedented territory. These advancements enable the realization of super-sensitive, miniaturized sensing instruments for measuring various physical parameters. The evolution of this field is propelled by a suite of sophisticated components, including miniaturized single-mode lasers, microfabricated alkali atom vapor cells, compact coil systems, scaled-down heating systems, and the application of cutting-edge micro-electro-mechanical system (MEMS) technologies. This review delves into the essential technologies needed to develop chip-scale hot atomic devices for quantum metrology, providing a comparative analysis of each technology's features. Concluding with a forward-looking perspective, this review discusses the future potential of chip-scale hot atomic devices and the critical technologies that will drive their advancement.
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Affiliation(s)
- Huiyao Yu
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Xuyuan Zhang
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Jian Zhang
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Zhendong Wu
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Long Jiao
- College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China
| | - Kan Li
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Wenqiang Zheng
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
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3
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Ilan Y. Free Will as Defined by the Constrained Disorder Principle: a Restricted, Mandatory, Personalized, Regulated Process for Decision-Making. Integr Psychol Behav Sci 2024:10.1007/s12124-024-09853-9. [PMID: 38900370 DOI: 10.1007/s12124-024-09853-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2024] [Indexed: 06/21/2024]
Abstract
The concept of free will has challenged physicists, biologists, philosophers, and other professionals for decades. The constrained disorder principle (CDP) is a fundamental law that defines systems according to their inherent variability. It provides mechanisms for adapting to dynamic environments. This work examines the CDP's perspective of free will concerning various free will theories. Per the CDP, systems lack intentions, and the "freedom" to select and act is built into their design. The "freedom" is embedded within the response range determined by the boundaries of the systems' variability. This built-in and self-generating mechanism enables systems to cope with perturbations. According to the CDP, neither dualism nor an unknown metaphysical apparatus dictates choices. Brain variability facilitates cognitive adaptation to complex, unpredictable situations across various environments. Human behaviors and decisions reflect an underlying physical variability in the brain and other organs for dealing with unpredictable noises. Choices are not predetermined but reflect the ongoing adaptation processes to dynamic prssu½res. Malfunctions and disease states are characterized by inappropriate variability, reflecting an inability to respond adequately to perturbations. Incorporating CDP-based interventions can overcome malfunctions and disease states and improve decision processes. CDP-based second-generation artificial intelligence platforms improve interventions and are being evaluated to augment personal development, wellness, and health.
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Affiliation(s)
- Yaron Ilan
- Faculty of Medicine, Hebrew University and Department of Medicine, Hadassah Medical Center, Jerusalem, Israel.
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4
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Mahdavifar S, Salehpour M, Cheraghi H, Afrousheh K. Resilience of quantum spin fluctuations against Dzyaloshinskii-Moriya interaction. Sci Rep 2024; 14:10034. [PMID: 38693194 PMCID: PMC11063192 DOI: 10.1038/s41598-024-60502-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: 10/12/2023] [Accepted: 04/23/2024] [Indexed: 05/03/2024] Open
Abstract
In low-dimensional systems, the lack of structural inversion symmetry combined with the spin-orbit coupling gives rise to an anisotropic antisymmetric superexchange known as the Dzyaloshinskii-Moriya interaction (DMI). Various features have been reported due to the presence of DMIs in quantum systems. We here study the one-dimensional spin-1/2 transverse field XY chains with a DMI at zero temperature. Our focus is on the quantum fluctuations of the spins measured by the spin squeezing and the entanglement entropy. We find that these fluctuations are resistant to the effect of the DMI in the system. This resistance will fail as soon as the system is placed in the chiral phase where its state behaves as a squeezed state, suggesting the merit of the chiral phase to be used for quantum metrology. Remarkably, we prove that the central charge vanishes on the critical lines between gapless chiral and ferromagnetic/paramagnetic phases where there is no critical scaling versus the system size for the spin squeezing parameter. Our phenomenal results provide a further understanding of the effects of the DMIs in the many-body quantum systems which may be testable in experiments.
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Affiliation(s)
- Saeed Mahdavifar
- Department of Physics, University of Guilan, Rasht, 41335-1914, Iran
| | | | - Hadi Cheraghi
- Computational Physics Laboratory, Physics Unit, Faculty of Engineering and Natural Sciences, Tampere University, FI-33014, Tampere, Finland
- Helsinki Institute of Physics, University of Helsinki, FI-00014, Helsinki, Finland
| | - Kourosh Afrousheh
- Department of Physics, Kuwait University, P. O. Box 5969, 13060, Safat, Kuwait.
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5
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Gutman N, Gorlach A, Tziperman O, Ruimy R, Kaminer I. Universal Control of Symmetric States Using Spin Squeezing. PHYSICAL REVIEW LETTERS 2024; 132:153601. [PMID: 38682988 DOI: 10.1103/physrevlett.132.153601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 03/11/2024] [Indexed: 05/01/2024]
Abstract
The manipulation of quantum many-body systems is a crucial goal in quantum science. Entangled quantum states that are symmetric under qubits permutation are of growing interest. Yet, the creation and control of symmetric states has remained a challenge. Here, we introduce a method to universally control symmetric states, proposing a scheme that relies solely on coherent rotations and spin squeezing. We present protocols for the creation of different symmetric states including Schrödinger's cat and Gottesman-Kitaev-Preskill states. The obtained symmetric states can be transferred to traveling photonic states via spontaneous emission, providing a powerful approach for engineering desired quantum photonic states.
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Affiliation(s)
- Nir Gutman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Alexey Gorlach
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Offek Tziperman
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ron Ruimy
- Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Ido Kaminer
- Technion-Israel Institute of Technology, Haifa 32000, Israel
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6
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Khastehdel Fumani F, Mahdavifar S, Afrousheh K. Entangled unique coherent line in the ground-state phase diagram of the spin-1/2 XX chain model with three-spin interaction. Phys Rev E 2024; 109:044142. [PMID: 38755842 DOI: 10.1103/physreve.109.044142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 03/19/2024] [Indexed: 05/18/2024]
Abstract
Entangled spin coherent states are a type of quantum states that involve two or more spin systems that are correlated in a nonclassical way. These states can improve metrology and information processing, as they can surpass the standard quantum limit, which is the ultimate bound for precision measurements using coherent states. However, finding entangled coherent states in physical systems is challenging because they require precise control and manipulation of the interactions between the modes. In this work we show that entangled unique coherent states can be found in the ground state of the spin-1/2 XX chain model with three-spin interaction, which is an exactly solvable model in quantum magnetism. We use the spin squeezing parameter, the l_{1}-norm of coherence, and the entanglement entropy as tools to detect and characterize these unique coherent states. We find that these unique coherent states exist in a gapless spin liquid phase, where they form a line that separates two regions with different degrees of squeezing. We call this line the entangled unique coherent line, as it corresponds to the almost maximum entanglement between two halves of the system. We also study the critical scaling of the spin squeezing parameter and the entanglement entropy versus the system size.
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Affiliation(s)
- F Khastehdel Fumani
- Department of Basic Sciences, Langarud Branch, Islamic Azad University, 4471311127 Langarud, Iran
| | - S Mahdavifar
- Department of Physics, University of Guilan, 41335-1914 Rasht, Iran
| | - K Afrousheh
- Department of Physics, Kuwait University, P.O. Box 5969, 13060 Safat, Kuwait
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7
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Ren ZQ, Lu XL, Xiang ZL. Heisenberg-limited spin squeezing in a hybrid system with silicon-vacancy centers. OPTICS EXPRESS 2024; 32:4013-4026. [PMID: 38297610 DOI: 10.1364/oe.499299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 01/08/2024] [Indexed: 02/02/2024]
Abstract
In this paper, we investigate the spin squeezing in a hybrid quantum system consisting of a Silicon-Vacancy (SiV) center ensemble coupled to a diamond acoustic waveguide via the strain interaction. Two sets of non-overlapping driving fields, each contains two time-dependent microwave fields, are applied to this hybrid system. By modulating these fields, the one-axis twist (OAT) interaction and two-axis two-spin (TATS) interaction can be independently realized. In the latter case the squeezing parameter scales to spin number as ξ R2∼1.61N -0.64 with the consideration of dissipation, which is very close to the Heisenberg limit. Furthermore, this hybrid system allows for the study of spin squeezing generated by the simultaneous presence of OAT and TATS interactions, which reveals sensitivity to the parity of the number of spins Ntot, whether it is even or odd. Our scheme enriches the approach for generating Heisenberg-limited spin squeezing in spin-phonon hybrid systems and offers the possibility for future applications in quantum information processing.
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8
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Jia J, Novikov V, Brasil TB, Zeuthen E, Müller JH, Polzik ES. Acoustic frequency atomic spin oscillator in the quantum regime. Nat Commun 2023; 14:6396. [PMID: 37828042 PMCID: PMC10570288 DOI: 10.1038/s41467-023-42059-y] [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: 03/16/2023] [Accepted: 09/28/2023] [Indexed: 10/14/2023] Open
Abstract
Quantum noise reduction and entanglement-enhanced sensing in the acoustic frequency range is an outstanding challenge relevant for a number of applications including magnetometry and broadband noise reduction in gravitational wave detectors. Here we experimentally demonstrate quantum behavior of a macroscopic atomic spin oscillator in the acoustic frequency range. Quantum back-action of the spin measurement, ponderomotive squeezing of light, and virtual spring softening are observed at oscillation frequencies down to the sub-kHz range. Quantum noise sources characteristic of spin oscillators operating in the near-DC frequency range are identified and means for their mitigation are presented.
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Affiliation(s)
- Jun Jia
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Valeriy Novikov
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- Russian Quantum Center, Skolkovo, Moscow, Russia
| | | | - Emil Zeuthen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | | | - Eugene S Polzik
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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9
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Zhao N, Zhang L, Yang Y, He J, Wang Y, Li T, Wang J. Characterizing current noise of commercial constant-current sources by using an optically pumped rubidium atomic magnetometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:095001. [PMID: 37655992 DOI: 10.1063/5.0159751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/10/2023] [Indexed: 09/02/2023]
Abstract
This paper introduces a method for characterizing the current noise of commercial constant-current sources (CCSs) using a free-induction-decay (FID) type optically pumped rubidium atomic magnetometer driven by a radio frequency magnetic field. We convert the sensitivity of the atomic magnetometer into the current noise of CCS by calibrating the coil constant. At the same time, the current noise characteristics of six typical commercial low-noise CCSs are compared. The current noise level of the Keysight model B2961A is the lowest among the six tested CCSs, which is 36.233 ± 0.022 nA/Hz1/2 at 1-25 Hz and 133.905 ± 0.080 nA/Hz1/2 at 1-100 Hz. The sensitivity of the atomic magnetometer is dependent on the current noise level of the CCS. The CCS with low noise is of great significance for high-sensitivity atomic magnetometers. This research provides an important reference for promoting the development of high precision CCS, metrology, and basic physics research.
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Affiliation(s)
- Ni Zhao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
| | - Lulu Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
| | - Yongbiao Yang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
| | - Jun He
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi Province, China
| | - Yanhua Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
- College of Physics and Electronic Engineering, Shanxi University, Taiyuan 030006, Shanxi Province, China
| | - Tingyu Li
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi Province, China
| | - Junmin Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, Shanxi Province, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi Province, China
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10
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Fedorov SA, Zeuthen E. Prediction-Retrodiction Measurements for Teleportation and Conditional State Transfer. PHYSICAL REVIEW LETTERS 2023; 131:060801. [PMID: 37625068 DOI: 10.1103/physrevlett.131.060801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 07/12/2023] [Indexed: 08/27/2023]
Abstract
Regular measurements allow predicting the future and retrodicting the past of quantum systems. Time-nonlocal measurements can leave the future and the past uncertain, yet establish a relation between them. We show that continuous time-nonlocal measurements can be used to transfer a quantum state via teleportation or direct transmission. Considering two oscillators probed by traveling fields, we analytically identify strategies for performing the state transfer perfectly across a wide range of linear oscillator-field interactions beyond the pure beam-splitter and two-mode-squeezing types.
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Affiliation(s)
- Sergey A Fedorov
- Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Emil Zeuthen
- Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen Ø, Denmark
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11
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Bai SY, An JH. Floquet Engineering to Overcome No-Go Theorem of Noisy Quantum Metrology. PHYSICAL REVIEW LETTERS 2023; 131:050801. [PMID: 37595225 DOI: 10.1103/physrevlett.131.050801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/17/2023] [Indexed: 08/20/2023]
Abstract
Permitting a more precise measurement to physical quantities than the classical limit by using quantum resources, quantum metrology holds a promise in developing many revolutionary technologies. However, the noise-induced decoherence forces its superiority to disappear, which is called no-go theorem of noisy quantum metrology and constrains its application. We propose a scheme to overcome the no-go theorem by Floquet engineering. It is found that, by applying a periodic driving on the atoms of the Ramsey spectroscopy, the ultimate sensitivity to measure their frequency characterized by quantum Fisher information returns to the ideal t^{2} scaling with the encoding time whenever a Floquet bound state is formed by the system consisting of each driven atom and its local noise. Combining with the optimal control, this mechanism also allows us to retrieve the ideal Heisenberg-limit scaling with the atom number N. Our result gives an efficient way to avoid the no-go theorem of noisy quantum metrology and to realize high-precision measurements.
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Affiliation(s)
- Si-Yuan Bai
- Key Laboratory of Quantum Theory and Applications of MoE, Lanzhou Center for Theoretical Physics, and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, China
| | - Jun-Hong An
- Key Laboratory of Quantum Theory and Applications of MoE, Lanzhou Center for Theoretical Physics, and Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, China
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12
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Liang C, Tang Y, Xu AN, Liu YC. Observation of Exceptional Points in Thermal Atomic Ensembles. PHYSICAL REVIEW LETTERS 2023; 130:263601. [PMID: 37450830 DOI: 10.1103/physrevlett.130.263601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/13/2023] [Indexed: 07/18/2023]
Abstract
Exceptional points (EPs) in non-Hermitian systems have recently attracted wide interest and spawned intriguing prospects for enhanced sensing. However, EPs have not yet been realized in thermal atomic ensembles, which is one of the most important platforms for quantum sensing. Here we experimentally observe EPs in multilevel thermal atomic ensembles and realize enhanced sensing of the magnetic field for 1 order of magnitude. We take advantage of the rich energy levels of atoms and construct effective decays for selected energy levels by employing laser coupling with the excited state, yielding unbalanced decay rates for different energy levels, which finally results in the existence of EPs. Furthermore, we propose the optical polarization rotation measurement scheme to detect the splitting of the resonance peaks, which makes use of both the absorption and dispersion properties and shows an advantage with enhanced splitting compared with the conventional transmission measurement scheme. Additionally, in our system both the effective coupling strength and decay rates are flexibly adjustable, and thus the position of the EPs are tunable, which expands the measurement range. Our Letter not only provides a new controllable platform for studying EPs and non-Hermitian physics, but also provide new ideas for the design of EP-enhanced sensors and opens up realistic opportunities for practical applications in the high-precision sensing of magnetic field and other physical quantities.
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Affiliation(s)
- Chao Liang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yuanjiang Tang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - An-Ning Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, 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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13
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Ho LB. Quantum backaction effects in sequential measurements. ANNALS OF PHYSICS 2023; 453:169310. [DOI: 10.1016/j.aop.2023.169310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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14
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Zheng W, Wang H, Schmieg R, Oesterle A, Polzik ES. Entanglement-Enhanced Magnetic Induction Tomography. PHYSICAL REVIEW LETTERS 2023; 130:203602. [PMID: 37267567 DOI: 10.1103/physrevlett.130.203602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 04/04/2023] [Indexed: 06/04/2023]
Abstract
Magnetic induction tomography (MIT) is a sensing protocol exploring conductive objects via their response to radio-frequency magnetic fields. MIT is used in nondestructive testing ranging from geophysics to medical applications. Atomic magnetometers, employed as MIT sensors, allow for significant improvement of the MIT sensitivity and for exploring its quantum limits. Here, we propose and verify a quantum-enhanced version of the atomic MIT by combining it with conditional spin squeezing and stroboscopic backaction evasion. We use this quantum enhancement to demonstrate sensitivity beyond the standard quantum limits of one-dimensional quantum MIT detecting a conductive sample.
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Affiliation(s)
- Wenqiang Zheng
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen ø, Denmark
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
| | - Hengyan Wang
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen ø, Denmark
- Department of Physics, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Rebecca Schmieg
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen ø, Denmark
| | - Alan Oesterle
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen ø, Denmark
| | - Eugene S Polzik
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen ø, Denmark
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15
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Chu Y, Li X, Cai J. Strong Quantum Metrological Limit from Many-Body Physics. PHYSICAL REVIEW LETTERS 2023; 130:170801. [PMID: 37172232 DOI: 10.1103/physrevlett.130.170801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/05/2023] [Accepted: 04/03/2023] [Indexed: 05/14/2023]
Abstract
Surpassing the standard quantum limit and even reaching the Heisenberg limit using quantum entanglement, represents the Holy Grail of quantum metrology. However, quantum entanglement is a valuable resource that does not come without a price. The exceptional time overhead for the preparation of large-scale entangled states raises disconcerting concerns about whether the Heisenberg limit is fundamentally achievable. Here, we find a universal speed limit set by the Lieb-Robinson light cone for the quantum Fisher information growth to characterize the metrological potential of quantum resource states during their preparation. Our main result establishes a strong precision limit of quantum metrology accounting for the complexity of many-body quantum resource state preparation and reveals a fundamental constraint for reaching the Heisenberg limit in a generic many-body lattice system with bounded one-site energy. It enables us to identify the essential features of quantum many-body systems that are crucial for achieving the quantum advantage of quantum metrology, and brings an interesting connection between many-body quantum dynamics and quantum metrology.
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Affiliation(s)
- Yaoming Chu
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiangbei Li
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jianming Cai
- School of Physics, International Joint Laboratory on Quantum Sensing and Quantum Metrology, Hubei Key Laboratory of Gravitation and Quantum Physics, Institute for Quantum Science and Engineering, Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China
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16
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Sundar B, Barberena D, Orioli AP, Chu A, Thompson JK, Rey AM, Lewis-Swan RJ. Bosonic Pair Production and Squeezing for Optical Phase Measurements in Long-Lived Dipoles Coupled to a Cavity. PHYSICAL REVIEW LETTERS 2023; 130:113202. [PMID: 37001062 DOI: 10.1103/physrevlett.130.113202] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 02/14/2023] [Indexed: 06/19/2023]
Abstract
We propose to simulate bosonic pair creation using large arrays of long-lived dipoles with multilevel internal structure coupled to an undriven optical cavity. Entanglement between the atoms, generated by the exchange of virtual photons through a common cavity mode, grows exponentially fast and is described by two-mode squeezing of effective bosonic quadratures. The mapping between an effective bosonic model and the natural spin description of the dipoles allows us to realize the analog of optical homodyne measurements via straightforward global rotations and population measurements of the electronic states, and we propose to exploit this for quantum-enhanced sensing of an optical phase (common and differential between two ensembles). We discuss a specific implementation based on Sr atoms and show that our sensing protocol is robust to sources of decoherence intrinsic to cavity platforms. Our proposal can open unique opportunities for next-generation optical atomic clocks.
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Affiliation(s)
- Bhuvanesh Sundar
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Diego Barberena
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Asier Piñeiro Orioli
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Anjun Chu
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - James K Thompson
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ana Maria Rey
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Robert J Lewis-Swan
- Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Center for Quantum Research and Technology, The University of Oklahoma, Norman, Oklahoma 73019, USA
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17
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Zhang L, Yang Y, Zhao N, He J, Wang J. A Multi-Pass Optically Pumped Rubidium Atomic Magnetometer with Free Induction Decay. SENSORS (BASEL, SWITZERLAND) 2022; 22:7598. [PMID: 36236696 PMCID: PMC9572103 DOI: 10.3390/s22197598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/24/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
A free-induction-decay (FID) type optically-pumped rubidium atomic magnetometer driven by a radio-frequency (RF) magnetic field is presented in this paper. Influences of parameters, such as the temperature of rubidium vapor cell, the power of pump beam, and the strength of RF magnetic field and static magnetic field on the amplitude and the full width at half maximum (FWHM) of the FID signal, have been investigated in the time domain and frequency domain. At the same time, the sensitivities of the magnetometer for the single-pass and the triple-pass probe beam cases have been compared by changing the optical path of the interaction between probe beam and atomic ensemble. Compared with the sensitivity of ∼21.2 pT/Hz1/2 in the case of the single-pass probe beam, the amplitude of FID signal in the case of the triple-pass probe beam has been significantly enhanced, and the sensitivity has been improved to ∼13.4 pT/Hz1/2. The research in this paper provids a reference for the subsequent study of influence of different buffer gas pressure on the FWHM and also a foundation for further improving the sensitivity of FID rubidium atomic magnetometer by employing a polarization-squeezed light as probe beam, to achieve a sensitivity beyond the photo-shot-noise level.
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Affiliation(s)
- Lulu Zhang
- State Key Laboratory of Quantum Optics and Quantum Optics Decices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
| | - Yongbiao Yang
- State Key Laboratory of Quantum Optics and Quantum Optics Decices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
| | - Ni Zhao
- State Key Laboratory of Quantum Optics and Quantum Optics Decices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
| | - Jun He
- State Key Laboratory of Quantum Optics and Quantum Optics Decices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Junmin Wang
- State Key Laboratory of Quantum Optics and Quantum Optics Decices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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18
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Hernández Yanes T, Płodzień M, Mackoit Sinkevičienė M, Žlabys G, Juzeliūnas G, Witkowska E. One- and Two-Axis Squeezing via Laser Coupling in an Atomic Fermi-Hubbard Model. PHYSICAL REVIEW LETTERS 2022; 129:090403. [PMID: 36083675 DOI: 10.1103/physrevlett.129.090403] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/05/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
Generation, storage, and utilization of correlated many-body quantum states are crucial objectives of future quantum technologies and metrology. Such states can be generated by the spin-squeezing protocols, i.e., one-axis twisting and two-axis countertwisting. In this Letter, we show activation of these two squeezing mechanisms in a system composed of ultracold atomic fermions in the Mott insulating phase by a position-dependent laser coupling of atomic internal states. Realization of both the squeezing protocols is feasible in the current state-of-the-art experiments.
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Affiliation(s)
- T Hernández Yanes
- Institute of Physics PAS, Aleja Lotnikow 32/46, 02-668 Warszawa, Poland
| | - M Płodzień
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Av. Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain
| | - M Mackoit Sinkevičienė
- Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio 3, LT-10257, Vilnius, Lithuania
| | - G Žlabys
- Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio 3, LT-10257, Vilnius, Lithuania
| | - G Juzeliūnas
- Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio 3, LT-10257, Vilnius, Lithuania
| | - E Witkowska
- Institute of Physics PAS, Aleja Lotnikow 32/46, 02-668 Warszawa, Poland
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19
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Torii A, Shibata K, Eto Y, Hirano T. Improved waveguide-based ultraviolet light generation and pulsed squeezing at 795 nm. OPTICS EXPRESS 2022; 30:26120-26135. [PMID: 36236809 DOI: 10.1364/oe.461507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/27/2022] [Indexed: 06/16/2023]
Abstract
We report on the waveguide-based generation of pulsed squeezed light at 795 nm, suitable for quantum enhanced measurements with rubidium atoms. Pulsed ultraviolet second harmonic light with a power of more than 400 mW is produced using a periodically poled LiNbO3 (PPLN) waveguide and is injected into another PPLN waveguide to generate quadrature squeezing. We find that the phase of the second harmonic pulse is shifted within a pulse, and we attribute the shift to heating due to blue-light induced infrared absorption (BLIIRA) from a comparison between the experiment and a numerical simulation. A squeezing level of -1.5(1) dB is observed in homodyne detection when we apply a linear phase shift to the local oscillator. The experiment and simulation imply that the squeezing level can be further improved by reducing BLIIRA.
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20
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Ma L, Lei X, Yan J, Li R, Chai T, Yan Z, Jia X, Xie C, Peng K. High-performance cavity-enhanced quantum memory with warm atomic cell. Nat Commun 2022; 13:2368. [PMID: 35501315 PMCID: PMC9061733 DOI: 10.1038/s41467-022-30077-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 04/14/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractHigh-performance quantum memory for quantized states of light is a prerequisite building block of quantum information technology. Despite great progresses of optical quantum memories based on interactions of light and atoms, physical features of these memories still cannot satisfy requirements for applications in practical quantum information systems, since all of them suffer from trade-off between memory efficiency and excess noise. Here, we report a high-performance cavity-enhanced electromagnetically-induced-transparency memory with warm atomic cell in which a scheme of optimizing the spatial and temporal modes based on the time-reversal approach is applied. The memory efficiency up to 67 ± 1% is directly measured and a noise level close to quantum noise limit is simultaneously reached. It has been experimentally demonstrated that the average fidelities for a set of input coherent states with different phases and amplitudes within a Gaussian distribution have exceeded the classical benchmark fidelities. Thus the realized quantum memory platform has been capable of preserving quantized optical states, and is ready to be applied in quantum information systems, such as distributed quantum logic gates and quantum-enhanced atomic magnetometry.
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21
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Bai L, Zhang L, Yang Y, Chang R, Qin Y, He J, Wen X, Wang J. Enhancement of spin noise spectroscopy of rubidium atomic ensemble by using the polarization squeezed light. OPTICS EXPRESS 2022; 30:1925-1936. [PMID: 35209344 DOI: 10.1364/oe.448084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
We measured the spin noise spectroscopy (SNS) of rubidium atomic ensemble with two different kinds of atomic vapor cells (filled with buffer gas or coated with paraffin film on the inner wall) and demonstrated the enhancement of the signal-to-noise ratio (SNR) by using polarization squeezed state (PSS) of 795-nm light field with Stokes operator S Λ 2 squeezed. The PSS is prepared by locking the relative phase between the squeezed vacuum state of light obtained with a sub-threshold optical parametric oscillator and the orthogonally polarized local oscillator beam by means of the quantum noise lock. Under the same conditions, the PSS can be employed not only to improve the SNR, but also to keep the full width at half maximum (FWHM) of SNS, compared with the case of using the polarization coherent state (PCS), enhancement of SNR is positively correlated with the squeezing level of the PSS. With increasing probe laser power and atomic number density, the SNR and FWHM of SNS will increase correspondingly. With the help of the PSS of the Stokes operator S Λ 2, quantum improvements of both the SNR and FWHM of SNS signal has been demonstrated by controlling optical power of polarization squeezed light beam or atomic number density in our experiments.
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22
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Li Y, Ren Y, Zhai H, Ai S, Liu X, Zhuang S. Single-beam highly sensitive magnetic field gradiometer based on the atomic spin-exchange relaxation-free effect. APPLIED OPTICS 2022; 61:149-156. [PMID: 35200814 DOI: 10.1364/ao.439542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
This paper presents a single-beam atomic magnetic field measurement gradiometer, which is a highly sensitive magnetic field gradient measuring instrument based on the atom spin-exchange relaxation-free (SERF) effect. The reflective detection optical path structure is adopted. The spin precession signals of an atom under incident and reflected light are different. There is also a difference in the corresponding magnetic field distribution. The final measurement of magnetic field gradients is conducted based on the different magnetic field distributions. The single-beam high-sensitive magnetic field gradiometers based on the atomic SERF effect are more sensitive than conventional two-probe magnetic field gradiometers or two-beam magnetic field gradiometers. The gradiometers are not affected by a difference in the detected optical power in the single-beam detection light measurements. The reflector uses an angular cone prism for two-dimensional magnetic field gradient measurements and is simple to construct. The single-beam highly sensitive magnetic field gradient measurement instrument based on the atomic SERF effect has a reflective detection optical path structure. It uses a quarter-wave plate to achieve the initial signal phase elimination of both incident and reflected signal and an angular cone prism as a reflector to achieve two-dimensional measurement.
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23
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Bai SY, An JH. Generating Stable Spin Squeezing by Squeezed-Reservoir Engineering. PHYSICAL REVIEW LETTERS 2021; 127:083602. [PMID: 34477431 DOI: 10.1103/physrevlett.127.083602] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/13/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
As a genuine many-body entanglement, spin squeezing (SS) can be used to realize the highly precise measurement beyond the limit constrained by classical physics. Its generation has attracted much attention recently. It was reported that N two-level systems (TLSs) located near a one-dimensional waveguide can generate SS by using the mediation effect of the waveguide. However, a coherent driving on each TLS is used to stabilize the SS, which raises a high requirement for experiments. We here propose a scheme to generate stable SS resorting to neither the spin-spin coupling nor the coherent driving on the TLSs. Incorporating the mediation role of the common waveguide and the technique of squeezed-reservoir engineering, our scheme exhibits the advantages over previous ones in the scaling relation of the SS parameter with the number of the TLSs. The long-range correlation feature of the generated SS along the waveguide in our scheme may endow it with certain superiority in quantum sensing, e.g., improving the sensing efficiency of spatially unidentified weak magnetic fields.
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Affiliation(s)
- Si-Yuan Bai
- Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, China
| | - Jun-Hong An
- Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou 730000, China
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24
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Xie T, Zhao Z, Kong X, Ma W, Wang M, Ye X, Yu P, Yang Z, Xu S, Wang P, Wang Y, Shi F, Du J. Beating the standard quantum limit under ambient conditions with solid-state spins. SCIENCE ADVANCES 2021; 7:7/32/eabg9204. [PMID: 34362736 PMCID: PMC8346219 DOI: 10.1126/sciadv.abg9204] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 06/21/2021] [Indexed: 05/16/2023]
Abstract
The use of entangled sensors improves the precision limit from the standard quantum limit (SQL) to the Heisenberg limit. Most previous experiments beating the SQL are performed on the sensors that are well isolated under extreme conditions. Here, we demonstrate a sub-SQL interferometer at ambient conditions by using a multispin system, namely, the nitrogen-vacancy (NV) defect in diamond. We achieve two-spin interference with a phase sensitivity of 1.79 ± 0.06 dB beyond the SQL and three-spin interference with a phase sensitivity of 2.77 ± 0.10 dB. Besides, a magnetic sensitivity of 0.87 ± 0.09 dB beyond the SQL is achieved by two-spin interference for detecting a real magnetic field. Particularly, the deterministic and joint initialization of NV negative state, NV electron spin, and two nuclear spins is realized at room temperature. The techniques used here are of fundamental importance for quantum sensing and computing, and naturally applicable to other solid-state spin systems.
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Affiliation(s)
- Tianyu Xie
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhiyuan Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xi Kong
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Wenchao Ma
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Mengqi Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Xiangyu Ye
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Pei Yu
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhiping Yang
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Shaoyi Xu
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Pengfei Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Ya Wang
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Fazhan Shi
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Jiangfeng Du
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
- CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
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25
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Shumilin AV, Smirnov DS. Nuclear Spin Dynamics, Noise, Squeezing, and Entanglement in Box Model. PHYSICAL REVIEW LETTERS 2021; 126:216804. [PMID: 34114866 DOI: 10.1103/physrevlett.126.216804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/24/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
We obtain a compact analytical solution for the nonlinear equation for the nuclear spin dynamics in the central spin box model in the limit of many nuclear spins. The total nuclear spin component along the external magnetic field is conserved and the two perpendicular components precess or oscillate depending on the electron spin polarization, with the frequency, determined by the nuclear spin polarization. As applications of our solution, we calculate the nuclear spin noise spectrum and describe the effects of nuclear spin squeezing and many body entanglement in the absence of a system excitation.
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Affiliation(s)
| | - D S Smirnov
- Ioffe Institute, 194021 St. Petersburg, Russia
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26
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Abstract
Prediction is the making of statements, usually probabilistic, about future events based on current information. Retrodiction is the making of statements about past events based on current information. We present the foundations of quantum retrodiction and highlight its intimate connection with the Bayesian interpretation of probability. The close link with Bayesian methods enables us to explore controversies and misunderstandings about retrodiction that have appeared in the literature. To be clear, quantum retrodiction is universally applicable and draws its validity directly from conventional predictive quantum theory coupled with Bayes’ theorem.
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27
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Jing M, Zhang P, Yuan S, Zhang L, Xiao L, Jia S. High bandwidth laser frequency locking for wideband noise suppression. OPTICS EXPRESS 2021; 29:7916-7924. [PMID: 33726283 DOI: 10.1364/oe.419832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
Ultra-low frequency noise lasers have been widely used in laser-based experiments. Most narrow-linewidth lasers are implemented by actively suppressing their frequency noise through a frequency noise servo loop (FNSL). The loop bandwidths (LBW) of FNSLs are currently below megahertz, which is gradually tricky to meet application requirements, especially for wideband quantum sensing experiments. This article has experimentally implemented an FNSL with loop-delay-limited 3.5 MHz LBW, which is an order higher than the usual FNSLs. Using this FNSL, we achieved 70 dB laser frequency noise suppression over 100 kHz Fourier frequency range. This technology has broad applications in vast fields where wideband laser frequency noise suppression is inevitable.
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Rossi MAC, Albarelli F, Tamascelli D, Genoni MG. Noisy Quantum Metrology Enhanced by Continuous Nondemolition Measurement. PHYSICAL REVIEW LETTERS 2020; 125:200505. [PMID: 33258625 DOI: 10.1103/physrevlett.125.200505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
We show that continuous quantum nondemolition (QND) measurement of an atomic ensemble is able to improve the precision of frequency estimation even in the presence of independent dephasing acting on each atom. We numerically simulate the dynamics of an ensemble with up to N=150 atoms initially prepared in a (classical) spin coherent state, and we show that, thanks to the spin squeezing dynamically generated by the measurement, the information obtainable from the continuous photocurrent scales superclassically with respect to the number of atoms N. We provide evidence that such superclassical scaling holds for different values of dephasing and monitoring efficiency. We moreover calculate the extra information obtainable via a final strong measurement on the conditional states generated during the dynamics and show that the corresponding ultimate limit is nearly achieved via a projective measurement of the spin-squeezed collective spin operator. We also briefly discuss the difference between our protocol and standard estimation schemes, where the state preparation time is neglected.
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Affiliation(s)
- Matteo A C Rossi
- QTF Centre of Excellence, Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turun Yliopisto, Finland
| | - Francesco Albarelli
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa, Poland
| | - Dario Tamascelli
- Dipartimento di Fisica "Aldo Pontremoli," Università degli Studi di Milano, I-20133 Milano, Italy
| | - Marco G Genoni
- Dipartimento di Fisica "Aldo Pontremoli," Università degli Studi di Milano, I-20133 Milano, Italy
- INFN - Sezione di Milano, I-20133 Milano, Italy
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29
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Retrodiction beyond the Heisenberg uncertainty relation. Nat Commun 2020; 11:5658. [PMID: 33168831 PMCID: PMC7652952 DOI: 10.1038/s41467-020-19495-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/14/2020] [Indexed: 11/23/2022] Open
Abstract
In quantum mechanics, the Heisenberg uncertainty relation presents an ultimate limit to the precision by which one can predict the outcome of position and momentum measurements on a particle. Heisenberg explicitly stated this relation for the prediction of “hypothetical future measurements”, and it does not describe the situation where knowledge is available about the system both earlier and later than the time of the measurement. Here, we study what happens under such circumstances with an atomic ensemble containing 1011 rubidium atoms, initiated nearly in the ground state in the presence of a magnetic field. The collective spin observables of the atoms are then well described by canonical position and momentum observables, \documentclass[12pt]{minimal}
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\begin{document}$$[{\hat{x}}_{\text{A}},{\hat{p}}_{\text{A}}]=i\hslash$$\end{document}[x^A,p^A]=iℏ. Quantum non-demolition measurements of \documentclass[12pt]{minimal}
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\begin{document}$${\hat{p}}_{\text{A}}$$\end{document}p^A before and of \documentclass[12pt]{minimal}
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\begin{document}$${\hat{x}}_{\text{A}}$$\end{document}x^A after time t allow precise estimates of both observables at time t. By means of the past quantum state formalism, we demonstrate that outcomes of measurements of both the \documentclass[12pt]{minimal}
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\begin{document}$${\hat{p}}_{A}$$\end{document}p^A observables can be inferred with errors below the standard quantum limit. The capability of assigning precise values to multiple observables and to observe their variation during physical processes may have implications in quantum state estimation and sensing. If we have access to information about a quantum system both before and after a measurement, we are not in the usual remit of the Heisenberg uncertainty principle anymore. Here, the authors demonstrate that, in such a scenario, one can retrodict position and momentum measurements without being limited by HUR.
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31
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Kong J, Jiménez-Martínez R, Troullinou C, Lucivero VG, Tóth G, Mitchell MW. Measurement-induced, spatially-extended entanglement in a hot, strongly-interacting atomic system. Nat Commun 2020; 11:2415. [PMID: 32415093 PMCID: PMC7229029 DOI: 10.1038/s41467-020-15899-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 03/16/2020] [Indexed: 11/11/2022] Open
Abstract
Quantum technologies use entanglement to outperform classical technologies, and often employ strong cooling and isolation to protect entangled entities from decoherence by random interactions. Here we show that the opposite strategy-promoting random interactions-can help generate and preserve entanglement. We use optical quantum non-demolition measurement to produce entanglement in a hot alkali vapor, in a regime dominated by random spin-exchange collisions. We use Bayesian statistics and spin-squeezing inequalities to show that at least 1.52(4) × 1013 of the 5.32(12) × 1013 participating atoms enter into singlet-type entangled states, which persist for tens of spin-thermalization times and span thousands of times the nearest-neighbor distance. The results show that high temperatures and strong random interactions need not destroy many-body quantum coherence, that collective measurement can produce very complex entangled states, and that the hot, strongly-interacting media now in use for extreme atomic sensing are well suited for sensing beyond the standard quantum limit.
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Affiliation(s)
- Jia Kong
- Department of Physics, Hangzhou Dianzi University, 310018, Hangzhou, China.
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain.
| | - Ricardo Jiménez-Martínez
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Charikleia Troullinou
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Vito Giovanni Lucivero
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Géza Tóth
- Department of Theoretical Physics, University of the Basque Country UPV/EHU, P.O. Box 644, E-48080, Bilbao, Spain
- Donostia International Physics Center, E-20018, San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, E-48011, Bilbao, Spain
- Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525, Budapest, Hungary
| | - Morgan W Mitchell
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain.
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010, Barcelona, Spain.
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