1
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Yang X, Cheng M, Xiao M. Enhancement of Entanglement via Incoherent Collisions. PHYSICAL REVIEW LETTERS 2024; 132:063601. [PMID: 38394603 DOI: 10.1103/physrevlett.132.063601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/10/2024] [Indexed: 02/25/2024]
Abstract
In contrast to the general thought that the collisions are intrinsically dephasing in nature and detrimental to quantum entanglement at room or higher temperatures, here, we show that in the conventional ladder-type electromagnetically induced transparency (EIT) configuration, when the probe field intensity is not very weak as compared to the pump field, the entanglement between the bright pump and probe fields can be remarkably enhanced with the increase of the collisional decay rates in a moderate range in an inhomogeneously broadened atomic system. The strengthened entanglement results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. Our results clearly indicate that the collisions offer a promising alternative to enhance entanglement at room or higher temperatures despite of the dephasing nature, which provides great convenience for experimental implementation, and opens new prospects and applications in realistic quantum computation and quantum information processing.
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Affiliation(s)
- Xihua Yang
- Department of Physics and Institute for Quantum Science and Technology, Shanghai University, Shanghai 200444, China
| | - Mingfei Cheng
- Department of Physics and Institute for Quantum Science and Technology, Shanghai University, Shanghai 200444, China
| | - Min Xiao
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
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2
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Cereceda-López E, Antonov AP, Ryabov A, Maass P, Tierno P. Overcrowding induces fast colloidal solitons in a slowly rotating potential landscape. Nat Commun 2023; 14:6448. [PMID: 37833258 PMCID: PMC10575966 DOI: 10.1038/s41467-023-41989-x] [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: 04/04/2023] [Accepted: 09/24/2023] [Indexed: 10/15/2023] Open
Abstract
Collective particle transport across periodic energy landscapes is ubiquitously present in many condensed matter systems spanning from vortices in high-temperature superconductors, frictional atomic sliding, driven skyrmions to biological and active matter. Here we report the emergence of fast solitons propagating against a rotating optical landscape. These experimentally observed solitons are stable cluster waves that originate from a coordinated particle exchange process which occurs when the number of trapped microparticles exceeds the number of potential wells. The size and speed of individual solitons rapidly increase with the particle diameter as predicted by theory and confirmed by numerical simulations. We show that when several solitons coexist, an effective repulsive interaction can stabilize their propagation along the periodic potential. Our experiments demonstrate a generic mechanism for cluster-mediated transport with potential applications to condensed matter systems on different length scales.
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Affiliation(s)
- Eric Cereceda-López
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028, Barcelona, Spain
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona (IN2UB), 08028, Barcelona, Spain
| | - Alexander P Antonov
- Universität Osnabrück, Fachbereich Physik, Barbarastraße 7, D-49076, Osnabrück, Germany
| | - Artem Ryabov
- Charles University, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, CZ-18000, Praha 8, Czech Republic.
| | - Philipp Maass
- Universität Osnabrück, Fachbereich Physik, Barbarastraße 7, D-49076, Osnabrück, Germany.
| | - Pietro Tierno
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028, Barcelona, Spain.
- Institut de Nanociència i Nanotecnologia, Universitat de Barcelona (IN2UB), 08028, Barcelona, Spain.
- University of Barcelona Institute of Complex Systems (UBICS), 08028, Barcelona, Spain.
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3
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Isichenko A, Chauhan N, Bose D, Wang J, Kunz PD, Blumenthal DJ. Photonic integrated beam delivery for a rubidium 3D magneto-optical trap. Nat Commun 2023; 14:3080. [PMID: 37248247 DOI: 10.1038/s41467-023-38818-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 05/17/2023] [Indexed: 05/31/2023] Open
Abstract
Cold atoms are important for precision atomic applications including timekeeping and sensing. The 3D magneto-optical trap (3D-MOT), used to produce cold atoms, will benefit from photonic integration to improve reliability and reduce size, weight, and cost. These traps require the delivery of multiple, large area, collimated laser beams to an atomic vacuum cell. Yet, to date, beam delivery using an integrated waveguide approach has remained elusive. Here we report the demonstration of a 87Rb 3D-MOT using a fiber-coupled photonic integrated circuit to deliver all beams to cool and trap > 1 ×106 atoms to near 200 μK. The silicon nitride photonic circuit transforms fiber-coupled 780 nm cooling and repump light via waveguides to three mm-width non-diverging free-space cooling and repump beams directly to the rubidium cell. This planar, CMOS foundry-compatible integrated beam delivery is compatible with other components, such as lasers and modulators, promising system-on-chip solutions for cold atom applications.
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Affiliation(s)
- Andrei Isichenko
- Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Nitesh Chauhan
- Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Debapam Bose
- Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Jiawei Wang
- Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Paul D Kunz
- DEVCOM U.S. Army Research Laboratory, Adelphi, MD, 20783, USA
| | - Daniel J Blumenthal
- Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA.
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4
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Ostrowski LA, Baker TJ, Saadatmand SN, Wiseman HM. No Tradeoff between Coherence and Sub-Poissonianity for Heisenberg-Limited Lasers. PHYSICAL REVIEW LETTERS 2023; 130:183602. [PMID: 37204878 DOI: 10.1103/physrevlett.130.183602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 03/27/2023] [Indexed: 05/21/2023]
Abstract
The Heisenberg limit to laser coherence C-the number of photons in the maximally populated mode of the laser beam-is the fourth power of the number of excitations inside the laser. We generalize the previous proof of this upper bound scaling by dropping the requirement that the beam photon statistics be Poissonian (i.e., Mandel's Q=0). We then show that the relation between C and sub-Poissonianity (Q<0) is win-win, not a tradeoff. For both regular (non-Markovian) pumping with semiunitary gain (which allows Q→-1), and random (Markovian) pumping with optimized gain, C is maximized when Q is minimized.
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Affiliation(s)
- L A Ostrowski
- Centre for Quantum Dynamics, Griffith University, Yuggera Country, Brisbane, Queensland 4111, Australia
| | - T J Baker
- Centre for Quantum Dynamics, Griffith University, Yuggera Country, Brisbane, Queensland 4111, Australia
| | - S N Saadatmand
- Centre for Quantum Dynamics, Griffith University, Yuggera Country, Brisbane, Queensland 4111, Australia
| | - H M Wiseman
- Centre for Quantum Dynamics, Griffith University, Yuggera Country, Brisbane, Queensland 4111, Australia
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5
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Song SY, Hua C, Bell L, Ko W, Fangohr H, Yan J, Halász GB, Dumitrescu EF, Lawrie BJ, Maksymovych P. Nematically Templated Vortex Lattices in Superconducting FeSe. NANO LETTERS 2023; 23:2822-2830. [PMID: 36940166 PMCID: PMC10103702 DOI: 10.1021/acs.nanolett.3c00125] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/16/2023] [Indexed: 06/18/2023]
Abstract
New pathways to controlling the morphology of superconducting vortex lattices─and their subsequent dynamics─are required to guide and scale vortex world-lines into a computing platform. We have found that the nematic twin boundaries align superconducting vortices in the adjacent terraces due to the incommensurate potential between vortices surrounding twin boundaries and those trapped within them. With the varying density and morphology of twin boundaries, the vortex lattice assumes several distinct structural phases, including square, regular, and irregular one-dimensional lattices. Through concomitant analysis of vortex lattice models, we have inferred the characteristic energetics of the twin boundary potential and furthermore predicted the existence of geometric size effects as a function of increasing confinement by the twin boundaries. These findings extend the ideas of directed control over vortex lattices to intrinsic topological defects and their self-organized networks, which have direct implications for the future design and control of strain-based topological quantum computing architectures.
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Affiliation(s)
- Sang Yong Song
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Chengyun Hua
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Luke Bell
- Department
of Physics, Yale University, New Haven, Connecticut 06520, United States
| | - Wonhee Ko
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department
of Physics and Astronomy, University of
Tennessee at Knoxville, Knoxville Tennessee 37996, United States
| | - Hans Fangohr
- Faculty
of Engineering and Physical Sciences, University
of Southampton, Southampton SO17 1BJ, U.K.
- Max Planck
Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jiaqiang Yan
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gábor B. Halász
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Eugene F. Dumitrescu
- Computational
Science and Engineering Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Benjamin J. Lawrie
- Materials
Science and Technology Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Petro Maksymovych
- Center
for Nanophase Materials Sciences, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37831, United States
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6
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Wang ZB, Gu C, Hu XX, Zhang YT, Zhang JZ, Li G, He XD, Zou XB, Dong CH, Guo GC, Zou CL. Controllable atomic collision in a tight optical dipole trap. OPTICS LETTERS 2023; 48:1064-1067. [PMID: 36791011 DOI: 10.1364/ol.479036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 01/12/2023] [Indexed: 06/18/2023]
Abstract
Single atoms are interesting candidates for studying quantum optics and quantum information processing. Recently, trapping and manipulation of single atoms using tight optical dipole traps has generated considerable interest. Here we report an experimental investigation of the dynamics of atoms in a modified optical dipole trap with a backward propagating dipole trap beam, where a change in the two-atom collision rate by six times has been achieved. The theoretical model presented gives a prediction of high probabilities of few-atom loading rates under proper experimental conditions. This work provides an alternative approach to the control of the few-atom dynamics in a dipole trap and the study of the collective quantum optical effects of a few atoms.
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7
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Chomaz L, Ferrier-Barbut I, Ferlaino F, Laburthe-Tolra B, Lev BL, Pfau T. Dipolar physics: a review of experiments with magnetic quantum gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 86:026401. [PMID: 36583342 DOI: 10.1088/1361-6633/aca814] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Since the achievement of quantum degeneracy in gases of chromium atoms in 2004, the experimental investigation of ultracold gases made of highly magnetic atoms has blossomed. The field has yielded the observation of many unprecedented phenomena, in particular those in which long-range and anisotropic dipole-dipole interactions (DDIs) play a crucial role. In this review, we aim to present the aspects of the magnetic quantum-gas platform that make it unique for exploring ultracold and quantum physics as well as to give a thorough overview of experimental achievements. Highly magnetic atoms distinguish themselves by the fact that their electronic ground-state configuration possesses a large electronic total angular momentum. This results in a large magnetic moment and a rich electronic transition spectrum. Such transitions are useful for cooling, trapping, and manipulating these atoms. The complex atomic structure and large dipolar moments of these atoms also lead to a dense spectrum of resonances in their two-body scattering behaviour. These resonances can be used to control the interatomic interactions and, in particular, the relative importance of contact over dipolar interactions. These features provide exquisite control knobs for exploring the few- and many-body physics of dipolar quantum gases. The study of dipolar effects in magnetic quantum gases has covered various few-body phenomena that are based on elastic and inelastic anisotropic scattering. Various many-body effects have also been demonstrated. These affect both the shape, stability, dynamics, and excitations of fully polarised repulsive Bose or Fermi gases. Beyond the mean-field instability, strong dipolar interactions competing with slightly weaker contact interactions between magnetic bosons yield new quantum-stabilised states, among which are self-bound droplets, droplet assemblies, and supersolids. Dipolar interactions also deeply affect the physics of atomic gases with an internal degree of freedom as these interactions intrinsically couple spin and atomic motion. Finally, long-range dipolar interactions can stabilise strongly correlated excited states of 1D gases and also impact the physics of lattice-confined systems, both at the spin-polarised level (Hubbard models with off-site interactions) and at the spinful level (XYZ models). In the present manuscript, we aim to provide an extensive overview of the various related experimental achievements up to the present.
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Affiliation(s)
- Lauriane Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - Igor Ferrier-Barbut
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127 Palaiseau, France
| | - Francesca Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - Bruno Laburthe-Tolra
- Université Sorbonne Paris Nord, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France
- CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - Benjamin L Lev
- Departments of Physics and Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA 94305, United States of America
| | - Tilman Pfau
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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8
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Decoherence Effects in a Three-Level System under Gaussian Process. Symmetry (Basel) 2022. [DOI: 10.3390/sym14122480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
When subjected to a classical fluctuating field characterized by a Gaussian process, we examine the purity and coherence protection in a three-level quantum system. This symmetry of the three-level system is examined when the local random field is investigated further in the noiseless and noisy regimes. In particular, we consider fractional Gaussian, Gaussian, Ornstein–Uhlenbeck, and power law noisy regimes. We show that the destructive nature of the Ornstein–Uhlenbeck noise toward the symmetry of the qutrit to preserve encoded purity and coherence remains large. Our findings suggest that properly adjusting the noisy parameters to specifically provided values can facilitate optimal extended purity and coherence survival. Non-vanishing terms appear in the final density matrix of the single qutrit system, indicating that it is in a strong coherence regime. Because of all of the Gaussian noises, monotonic decay with no revivals has been observed in the single qutrit system. In terms of coherence and information preservation, we find that the current qutrit system outperforms systems with multiple qubits or qutrits using purity and von Neumann entropy. A comparison of noisy and noiseless situations shows that the fluctuating nature of the local random fields is ultimately lost when influenced using the classical Gaussian noises.
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9
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10
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Haga T, Nakagawa M, Hamazaki R, Ueda M. Liouvillian Skin Effect: Slowing Down of Relaxation Processes without Gap Closing. PHYSICAL REVIEW LETTERS 2021; 127:070402. [PMID: 34459629 DOI: 10.1103/physrevlett.127.070402] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/21/2021] [Indexed: 06/13/2023]
Abstract
It is highly nontrivial to what extent we can deduce the relaxation behavior of a quantum dissipative system from the spectral gap of the Liouvillian that governs the time evolution of the density matrix. We investigate the relaxation processes of a quantum dissipative system that exhibits the Liouvillian skin effect, which means that the eigenmodes of the Liouvillian are localized exponentially close to the boundary of the system, and find that the timescale for the system to reach a steady state depends not only on the Liouvillian gap Δ, but also on the localization length ξ of the eigenmodes. In particular, we show that the longest relaxation time τ that is maximized over initial states and local observables is given by τ∼Δ^{-1}(1+L/ξ) with L being the system size. This implies that the longest relaxation time can diverge for L→∞ without gap closing.
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Affiliation(s)
- Taiki Haga
- Department of Physics and Electronics, Osaka Prefecture University, Sakai-shi, Osaka 599-8531, Japan
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masaya Nakagawa
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ryusuke Hamazaki
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR), RIKEN iTHEMS, Wako, Saitama 351-0198, Japan
| | - Masahito Ueda
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Institute for Physics of Intelligence, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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11
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Abstract
Narrow linewidth visible light lasers are critical for atomic, molecular and optical (AMO) physics including atomic clocks, quantum computing, atomic and molecular spectroscopy, and sensing. Stimulated Brillouin scattering (SBS) is a promising approach to realize highly coherent on-chip visible light laser emission. Here we report demonstration of a visible light photonic integrated Brillouin laser, with emission at 674 nm, a 14.7 mW optical threshold, corresponding to a threshold density of 4.92 mW μm-2, and a 269 Hz linewidth. Significant advances in visible light silicon nitride/silica all-waveguide resonators are achieved to overcome barriers to SBS in the visible, including 1 dB/meter waveguide losses, 55.4 million quality factor (Q), and measurement of the 25.110 GHz Stokes frequency shift and 290 MHz gain bandwidth. This advancement in integrated ultra-narrow linewidth visible wavelength SBS lasers opens the door to compact quantum and atomic systems and implementation of increasingly complex AMO based physics and experiments.
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12
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Stanke M, Palikot E, Sharkey KL, Adamowicz L. Benchmark calculations of the 2D Rydberg spectrum of lithium. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1925765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Monika Stanke
- Institute of Physics, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University, Toruń, PL, Poland
| | - Ewa Palikot
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Keeper L. Sharkey
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Ludwik Adamowicz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
- Interdisciplinary Center for Modern Technologies, Nicolaus Copernicus University, Toruń, PL, Poland
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13
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Pelissetto A, Rossini D, Vicari E. Scaling properties of the dynamics at first-order quantum transitions when boundary conditions favor one of the two phases. Phys Rev E 2020; 102:012143. [PMID: 32795036 DOI: 10.1103/physreve.102.012143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
We address the out-of-equilibrium dynamics of a many-body system when one of its Hamiltonian parameters is driven across a first-order quantum transition (FOQT). In particular, we consider systems subject to boundary conditions favoring one of the two phases separated by the FOQT. These issues are investigated within the paradigmatic one-dimensional quantum Ising model, at the FOQTs driven by the longitudinal magnetic field h, with boundary conditions that favor the same magnetized phase (EFBC) or opposite magnetized phases (OFBC). We study the dynamic behavior for an instantaneous quench and for a protocol in which h is slowly varied across the FOQT. We develop a dynamic finite-size scaling theory for both EFBC and OFBC, which displays some remarkable differences with respect to the case of neutral boundary conditions. The corresponding relevant timescale shows a qualitative different size dependence in the two cases: it increases exponentially with the size in the case of EFBC, and as a power of the size in the case of OFBC.
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Affiliation(s)
- Andrea Pelissetto
- Dipartimento di Fisica dell'Università di Roma "La Sapienza" and INFN, Sezione di Roma I, I-00185 Roma, Italy
| | - Davide Rossini
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Ettore Vicari
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
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14
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Pereira LC, do Nascimento VA. Dynamics of Bose-Einstein Condensates Subject to the Pöschl-Teller Potential through Numerical and Variational Solutions of the Gross-Pitaevskii Equation. MATERIALS 2020; 13:ma13102236. [PMID: 32414029 PMCID: PMC7287778 DOI: 10.3390/ma13102236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/15/2020] [Accepted: 04/20/2020] [Indexed: 11/16/2022]
Abstract
We present for the first time an approach about Bose–Einstein condensates made up of atoms with attractive interatomic interactions confined to the Pöschl–Teller hyperbolic potential. In this paper, we consider a Bose–Einstein condensate confined in a cigar-shaped, and it was modeled by the mean field equation known as the Gross–Pitaevskii equation. An analytical (variational method) and numerical (two-step Crank–Nicolson) approach is proposed to study the proposed model of interatomic interaction. The solutions of the one-dimensional Gross–Pitaevskii equation obtained in this paper confirmed, from a theoretical point of view, the possibility of the Pöschl–Teller potential to confine Bose–Einstein condensates. The chemical potential as a function of the depth of the Pöschl–Teller potential showed a behavior very similar to the cases of Bose–Einstein condensates and superfluid Fermi gases in optical lattices and optical superlattices. The results presented in this paper can open the way for several applications in atomic and molecular physics, solid state physics, condensed matter physics, and material sciences.
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Affiliation(s)
- Lucas Carvalho Pereira
- Programa de Pós-Graduaçāo em Ciência dos Materiais, Instituto de Física, Universidade Federal de Mato Grosso do Sul, Campo Grande 79070-900, Mato Grosso do Sul, Brazil
- Correspondence: ; Tel.: +55-67-99280-9266
| | - Valter Aragão do Nascimento
- Group of Spectroscopy and Bioinformatics Applied to Biodiversity and Health, School of Medicine, Postgraduation Program in Health and Development in the Midwest Region, Faculty of Medicine, Federal University of Mato Grosso do Sul, Campo Grande 79070-900, Mato Grosso do Sul, Brazil;
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15
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Lü LJ, Bian XB. Ultrafast intraband electron dynamics of preexcited SiO 2. OPTICS EXPRESS 2020; 28:13432-13442. [PMID: 32403818 DOI: 10.1364/oe.391704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Intraband high-order harmonics in solids reflect the nonlinear motion of carriers in the energy bands and have important applications. In general, multiple energy bands contribute to the intraband harmonics. We reveal the interference mechanism of intraband harmonics between electrons and holes by using the k-resolved semiclassical intraband model. The model gives a quantitative relationship between the intraband radiation yield, the energy band dispersion, and the laser parameters. Based on a preexcitation scheme, we present a method to reconstruct energy bands by using the intraband harmonics. We simulate the intraband harmonics of photo-carriers polarized by a bias field. The variation of harmonic yields as a function of a delay time results from the k-resolved energy band dispersion and reflects the Bloch oscillation of photo-carriers driven by the bias field.
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16
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Schäfer F, Bastarrachea-Magnani MA, Lode AUJ, de Parny LDF, Buchleitner A. Spectral Structure and Many-Body Dynamics of Ultracold Bosons in a Double-Well. ENTROPY (BASEL, SWITZERLAND) 2020; 22:E382. [PMID: 33286153 PMCID: PMC7516856 DOI: 10.3390/e22040382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 11/17/2022]
Abstract
We examine the spectral structure and many-body dynamics of two and three repulsively interacting bosons trapped in a one-dimensional double-well, for variable barrier height, inter-particle interaction strength, and initial conditions. By exact diagonalization of the many-particle Hamiltonian, we specifically explore the dynamical behavior of the particles launched either at the single-particle ground state or saddle-point energy, in a time-independent potential. We complement these results by a characterization of the cross-over from diabatic to quasi-adiabatic evolution under finite-time switching of the potential barrier, via the associated time evolution of a single particle's von Neumann entropy. This is achieved with the help of the multiconfigurational time-dependent Hartree method for indistinguishable particles (MCTDH-X)-which also allows us to extrapolate our results for increasing particle numbers.
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Affiliation(s)
- Frank Schäfer
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany; (M.A.B.-M.); (A.U.J.L.); (L.d.F.d.P.)
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Miguel A. Bastarrachea-Magnani
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany; (M.A.B.-M.); (A.U.J.L.); (L.d.F.d.P.)
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - Axel U. J. Lode
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany; (M.A.B.-M.); (A.U.J.L.); (L.d.F.d.P.)
| | - Laurent de Forges de Parny
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany; (M.A.B.-M.); (A.U.J.L.); (L.d.F.d.P.)
- ACRI-ST, 260 route du Pin Montard, 06904 Sophia Antipolis CEDEX, France
| | - Andreas Buchleitner
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany; (M.A.B.-M.); (A.U.J.L.); (L.d.F.d.P.)
- Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstr. 19, D-79104 Freiburg, Germany
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17
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Katz O, Shaham R, Polzik ES, Firstenberg O. Long-Lived Entanglement Generation of Nuclear Spins Using Coherent Light. PHYSICAL REVIEW LETTERS 2020; 124:043602. [PMID: 32058754 DOI: 10.1103/physrevlett.124.043602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Indexed: 06/10/2023]
Abstract
Nuclear spins of noble-gas atoms are exceptionally isolated from the environment and can maintain their quantum properties for hours at room temperature. Here we develop a mechanism for entangling two such distant macroscopic ensembles by using coherent light input. The interaction between the light and the noble-gas spins in each ensemble is mediated by spin-exchange collisions with alkali-metal spins, which are only virtually excited. The relevant conditions for experimental realizations with ^{3}He or ^{129}Xe are outlined.
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Affiliation(s)
- Or Katz
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
- Rafael Ltd, IL-31021 Haifa, Israel
| | - Roy Shaham
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
- Rafael Ltd, IL-31021 Haifa, Israel
| | - Eugene S Polzik
- Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark
| | - Ofer Firstenberg
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
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18
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Abstract
The ability to control and separate individual active particles in fluid layers is a challenge in biological and engineering contexts as well as a basic problem of controlled self-assembly. Here we place spinners in a wave-driven matrix of vortices, akin to optical lattices. The results offer a method of manipulating spinning particles within a wave-produced flow. Spinners can be confined on stable orbits, trapped inside, or released from the liquid metamaterial cells without solid boundaries and can be used to carry biological or chemical agents within the vortex lattice. We show that rotating particles at the liquid–gas interface can be efficiently manipulated using the surface-wave analogue of optical lattices. Two orthogonal standing waves generate surface flows of counter-rotating half-wavelength unit cells, the liquid interface metamaterial, whose geometry is controlled by the wave phase shift. Here we demonstrate that by placing active magnetic spinners inside such metamaterials, one makes a powerful tool which allows manipulation and self-assembly of spinners, turning them into vehicles capable of transporting matter and information between autonomous metamaterial unit cells. We discuss forces acting on a spinner carried by a nonuniform flow and show how the forces confine spinners to orbit inside the same-sign vortex cells of the wave-driven flow. Reversing the spin, we move the spinner into an adjacent cell. By changing the spinning frequency or the wave amplitude, one can precisely control the spinner orbit. Multiple spinners within a unit cell self-organize into stable patterns, e.g., triangles or squares, orbiting around the center of the cell. Spinners having different frequencies can also be confined, such that the higher-frequency spinner occupies the inner orbit and the lower-frequency one circles on the outer orbit, while the orbital motions of both spinners are synchronized.
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19
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Wernsdorfer W, Ruben M. Synthetic Hilbert Space Engineering of Molecular Qudits: Isotopologue Chemistry. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1806687. [PMID: 30803060 DOI: 10.1002/adma.201806687] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/09/2019] [Indexed: 06/09/2023]
Abstract
One of the most ambitious technological goals is the development of devices working under the laws of quantum mechanics. Among others, an important challenge to be resolved on the way to such breakthrough technology concerns the scalability of the available Hilbert space. Recently, proof-of-principle experiments were reported, in which the implementation of quantum algorithms (the Grover's search algorithm, iSWAP-gate, etc.) in a single-molecule nuclear spin qudit (with d = 4) known as 159 TbPc2 was described, where the nuclear spins of lanthanides are used as a quantum register to execute simple quantum algorithms. In this progress report, the goal of linear and exponential up-scalability of the available Hilbert space expressed by the qudit-dimension "d" is addressed by synthesizing lanthanide metal complexes as quantum computing hardware. The synthesis of multinuclear large-Hilbert-space complexes has to be carried out under strict control of the nuclear spin degree of freedom leading to isotopologues, whereby electronic coupling between several nuclear spin units will exponentially extend the Hilbert space available for quantum information processing. Thus, improved multilevel spin qudits can be achieved that exhibit an exponentially scalable Hilbert space to enable high-performance quantum computing and information storage.
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Affiliation(s)
- Wolfgang Wernsdorfer
- Institute of Physics (PHI), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, D-76131, Karlsruhe, Germany
- Institute of Nanotechnology (INT) and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344, Eggenstein-Leopoldshafen, Germany
| | - Mario Ruben
- Institute of Nanotechnology (INT) and Institute of Quantum Materials and Technology (IQMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344, Eggenstein-Leopoldshafen, Germany
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS, Université de Strasbourg, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
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20
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Sciara S, Reimer C, Kues M, Roztocki P, Cino A, Moss DJ, Caspani L, Munro WJ, Morandotti R. Universal N-Partite d-Level Pure-State Entanglement Witness Based on Realistic Measurement Settings. PHYSICAL REVIEW LETTERS 2019; 122:120501. [PMID: 30978097 DOI: 10.1103/physrevlett.122.120501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Indexed: 06/09/2023]
Abstract
Entanglement witnesses are operators that are crucial for confirming the generation of specific quantum systems, such as multipartite and high-dimensional states. For this reason, many witnesses have been theoretically derived which commonly focus on establishing tight bounds and exhibit mathematical compactness as well as symmetry properties similar to that of the quantum state. However, for increasingly complex quantum systems, established witnesses have lacked experimental achievability, as it has become progressively more challenging to design the corresponding experiments. Here, we present a universal approach to derive entanglement witnesses that are capable of detecting the presence of any targeted complex pure quantum system and that can be customized towards experimental restrictions or accessible measurement settings. Using this technique, we derive experimentally optimized witnesses that are able to detect multipartite d-level cluster states, and that require only two measurement settings. We present explicit examples for customizing the witness operators given different realistic experimental restrictions, including witnesses for high-dimensional entanglement that use only two-dimensional projection measurements. Our work enables us to confirm the presence of probed quantum states using methods that are compatible with practical experimental realizations in different quantum platforms.
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Affiliation(s)
- Stefania Sciara
- Institut National de la Recherche Scientifique-Centre Énergie, Matériaux et Télécommunications (INRS-EMT), 1650 Boulevard Lione-Boulet, Varennes, Québec J3X 1S2, Canada
- Department of Engineering, University of Palermo, Palermo 90100, Italy
| | - Christian Reimer
- Institut National de la Recherche Scientifique-Centre Énergie, Matériaux et Télécommunications (INRS-EMT), 1650 Boulevard Lione-Boulet, Varennes, Québec J3X 1S2, Canada
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Michael Kues
- School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
- Hannover Center for Optical Technologies (HOT), Leibniz University Hannover, Hannover 30167, Germany
| | - Piotr Roztocki
- Institut National de la Recherche Scientifique-Centre Énergie, Matériaux et Télécommunications (INRS-EMT), 1650 Boulevard Lione-Boulet, Varennes, Québec J3X 1S2, Canada
| | - Alfonso Cino
- Department of Engineering, University of Palermo, Palermo 90100, Italy
| | - David J Moss
- Centre for Micro Photonics, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Lucia Caspani
- Institute of Photonics, Department of Physics, University of Strathclyde, Glasgow G1 1RD, United Kingdom
| | - William J Munro
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Kanagawa, 243-0198, Japan
- National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan
| | - Roberto Morandotti
- Institut National de la Recherche Scientifique-Centre Énergie, Matériaux et Télécommunications (INRS-EMT), 1650 Boulevard Lione-Boulet, Varennes, Québec J3X 1S2, Canada
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chendu 610054, China
- ITMO University, St. Petersburg 197101, Russia
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21
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Gholizadeh S, Yahyavi M, Hetényi B. Extended Creutz ladder with spin-orbit coupling: A one-dimensional analog of the Kane-Mele model. ACTA ACUST UNITED AC 2018. [DOI: 10.1209/0295-5075/122/27001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Pelissetto A, Rossini D, Vicari E. Dynamic finite-size scaling after a quench at quantum transitions. Phys Rev E 2018; 97:052148. [PMID: 29906825 DOI: 10.1103/physreve.97.052148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Indexed: 06/08/2023]
Abstract
We present a general dynamic finite-size scaling theory for the quantum dynamics after an abrupt quench, at both continuous and first-order quantum transitions. For continuous transitions, the scaling laws are naturally ruled by the critical exponents and the renormalization-group dimension of the perturbation at the transition. In the case of first-order transitions, it is possible to recover a universal scaling behavior, which is controlled by the size behavior of the energy gap between the lowest-energy levels. We discuss these findings in the framework of the paradigmatic quantum Ising ring, and support the dynamic scaling laws by numerical evidence.
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Affiliation(s)
- Andrea Pelissetto
- Dipartimento di Fisica dell'Università di Roma "La Sapienza" and INFN, Sezione di Roma I, I-00185 Roma, Italy
| | - Davide Rossini
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Ettore Vicari
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
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23
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Kunkel P, Prüfer M, Strobel H, Linnemann D, Frölian A, Gasenzer T, Gärttner M, Oberthaler MK. Spatially distributed multipartite entanglement enables EPR steering of atomic clouds. Science 2018; 360:413-416. [DOI: 10.1126/science.aao2254] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 02/16/2018] [Indexed: 11/02/2022]
Abstract
A key resource for distributed quantum-enhanced protocols is entanglement between spatially separated modes. However, the robust generation and detection of entanglement between spatially separated regions of an ultracold atomic system remain a challenge. We used spin mixing in a tightly confined Bose-Einstein condensate to generate an entangled state of indistinguishable particles in a single spatial mode. We show experimentally that this entanglement can be spatially distributed by self-similar expansion of the atomic cloud. We used spatially resolved spin read-out to reveal a particularly strong form of quantum correlations known as Einstein-Podolsky-Rosen (EPR) steering between distinct parts of the expanded cloud. Based on the strength of EPR steering, we constructed a witness, which confirmed genuine 5-partite entanglement.
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Affiliation(s)
- Philipp Kunkel
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Maximilian Prüfer
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Helmut Strobel
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Daniel Linnemann
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Anika Frölian
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Thomas Gasenzer
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Martin Gärttner
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
| | - Markus K. Oberthaler
- Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany
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24
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Hetényi B, Yahyavi M. Topological insulation in a ladder model with particle-hole and reflection symmetries. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:10LT01. [PMID: 29393064 DOI: 10.1088/1361-648x/aaac9d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A two-legged ladder model, one dimensional, exhibiting the parity anomaly is constructed. The model belongs to the C and CI symmetry classes, depending on the parameters, but, due to reflection, it exhibits topological insulation. The model consists of two superimposed Creutz models with onsite potentials. The topological invariants of each Creutz model sum to give the mirror winding number, with winding numbers which are nonzero individually but equal and opposite in the topological phase, and both zero in the trivial phase. We demonstrate the presence of edge states and quantized Hall response in the topological region. Our model exhibits two distinct topological regions, distinguished by the different types of reflection symmetries.
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Affiliation(s)
- B Hetényi
- Department of Physics, Bilkent University, TR-06800 Bilkent, Ankara, Turkey. MTA-BME Exotic Quantum Phases 'Momentum' Research Group, Department of Physics, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
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25
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Moreno-Pineda E, Godfrin C, Balestro F, Wernsdorfer W, Ruben M. Molecular spin qudits for quantum algorithms. Chem Soc Rev 2018; 47:501-513. [PMID: 29147698 DOI: 10.1039/c5cs00933b] [Citation(s) in RCA: 174] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Presently, one of the most ambitious technological goals is the development of devices working under the laws of quantum mechanics. One prominent target is the quantum computer, which would allow the processing of information at quantum level for purposes not achievable with even the most powerful computer resources. The large-scale implementation of quantum information would be a game changer for current technology, because it would allow unprecedented parallelised computation and secure encryption based on the principles of quantum superposition and entanglement. Currently, there are several physical platforms racing to achieve the level of performance required for the quantum hardware to step into the realm of practical quantum information applications. Several materials have been proposed to fulfil this task, ranging from quantum dots, Bose-Einstein condensates, spin impurities, superconducting circuits, molecules, amongst others. Magnetic molecules are among the list of promising building blocks, due to (i) their intrinsic monodispersity, (ii) discrete energy levels (iii) the possibility of chemical quantum state engineering, and (iv) their multilevel characteristics that lead to Qudits, where the dimension of the Hilbert space is d > 2. Herein we review how a molecular nuclear spin qudit, (d = 4), known as TbPc2, gathers all the necessary requirements to perform as a molecular hardware platform with a first generation of molecular devices enabling even quantum algorithm operations.
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Affiliation(s)
- Eufemio Moreno-Pineda
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
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26
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Notarnicola S, Iemini F, Rossini D, Fazio R, Silva A, Russomanno A. From localization to anomalous diffusion in the dynamics of coupled kicked rotors. Phys Rev E 2018; 97:022202. [PMID: 29548167 DOI: 10.1103/physreve.97.022202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Indexed: 06/08/2023]
Abstract
We study the effect of many-body quantum interference on the dynamics of coupled periodically kicked systems whose classical dynamics is chaotic and shows an unbounded energy increase. We specifically focus on an N-coupled kicked rotors model: We find that the interplay of quantumness and interactions dramatically modifies the system dynamics, inducing a transition between energy saturation and unbounded energy increase. We discuss this phenomenon both numerically and analytically through a mapping onto an N-dimensional Anderson model. The thermodynamic limit N→∞, in particular, always shows unbounded energy growth. This dynamical delocalization is genuinely quantum and very different from the classical one: Using a mean-field approximation, we see that the system self-organizes so that the energy per site increases in time as a power law with exponent smaller than 1. This wealth of phenomena is a genuine effect of quantum interference: The classical system for N≥2 always behaves ergodically with an energy per site linearly increasing in time. Our results show that quantum mechanics can deeply alter the regularity or ergodicity properties of a many-body-driven system.
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Affiliation(s)
| | - Fernando Iemini
- Abdus Salam ICTP, Strada Costiera 11, I-34151 Trieste, Italy
| | - Davide Rossini
- Dipartimento di Fisica, Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Rosario Fazio
- Abdus Salam ICTP, Strada Costiera 11, I-34151 Trieste, Italy
- NEST, Scuola Normale Superiore & Istituto Nanoscienze-CNR, I-56126 Pisa, Italy
| | | | - Angelo Russomanno
- Abdus Salam ICTP, Strada Costiera 11, I-34151 Trieste, Italy
- NEST, Scuola Normale Superiore & Istituto Nanoscienze-CNR, I-56126 Pisa, Italy
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27
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Geiger B, Urbina JD, Hummel Q, Richter K. Semiclassics in a system without classical limit: The few-body spectrum of two interacting bosons in one dimension. Phys Rev E 2017; 96:022204. [PMID: 28950541 DOI: 10.1103/physreve.96.022204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Indexed: 11/07/2022]
Abstract
We present a semiclassical study of the spectrum of a few-body system consisting of two short-range interacting bosonic particles in one dimension, a particular case of a general class of integrable many-body systems where the energy spectrum is given by the solution of algebraic transcendental equations. By an exact mapping between δ-potentials and boundary conditions on the few-body wave functions, we are able to extend previous semiclassical results for single-particle systems with mixed boundary conditions to the two-body problem. The semiclassical approach allows us to derive explicit analytical results for the smooth part of the two-body density of states that are in excellent agreement with numerical calculations. It further enables us to include the effect of bound states in the attractive case. Remarkably, for the particular case of two particles in one dimension, the discrete energy levels obtained through a requantization condition of the smooth density of states are essentially in perfect agreement with the exact ones.
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Affiliation(s)
- Benjamin Geiger
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - Juan-Diego Urbina
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - Quirin Hummel
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - Klaus Richter
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
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28
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Sacchetti A. Bifurcation trees of Stark-Wannier ladders for accelerated Bose-Einstein condensates in an optical lattice. Phys Rev E 2017; 95:062212. [PMID: 28709302 DOI: 10.1103/physreve.95.062212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Indexed: 06/07/2023]
Abstract
In this paper we show that in the semiclassical regime of periodic potential large enough, the Stark-Wannier ladders become a dense energy spectrum because of a cascade of bifurcations while increasing the ratio between the effective nonlinearity strength and the tilt of the external field; this fact is associated to a transition from regular to quantum chaotic dynamics. The sequence of bifurcation points is explicitly given.
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Affiliation(s)
- Andrea Sacchetti
- Department of Physics, Informatics and Mathematics, University of Modena e Reggio Emilia, Via G. Campi 213/A, Modena 41125, Italy
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29
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Witthaut D, Wimberger S, Burioni R, Timme M. Classical synchronization indicates persistent entanglement in isolated quantum systems. Nat Commun 2017; 8:14829. [PMID: 28401881 PMCID: PMC5394286 DOI: 10.1038/ncomms14829] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 12/16/2017] [Indexed: 11/29/2022] Open
Abstract
Synchronization and entanglement constitute fundamental collective phenomena in multi-unit classical and quantum systems, respectively, both equally implying coordinated system states. Here, we present a direct link for a class of isolated quantum many-body systems, demonstrating that synchronization emerges as an intrinsic system feature. Intriguingly, quantum coherence and entanglement arise persistently through the same transition as synchronization. This direct link between classical and quantum cooperative phenomena may further our understanding of strongly correlated quantum systems and can be readily observed in state-of-the-art experiments, for example, with ultracold atoms. Collective phenomena in many-body systems include synchronization in classical and entanglement in quantum systems. Here the authors study isolated many-body quantum systems and demonstrate that synchronization emerges intrinsically, accompanied by the onset of quantum coherence and persistent entanglement.
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Affiliation(s)
- Dirk Witthaut
- Forschungszentrum Jülich, Institute for Energy and Climate Research (IEK-STE), 52428 Jülich, Germany.,Institute for Theoretical Physics, University of Cologne, Zuelpicher Str. 77, 50937 Köln, Germany.,Network Dynamics, Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Faßberg, 37077 Göttingen, Germany
| | - Sandro Wimberger
- Dipartimento di Scienze Matematiche, Fisiche ed Informatiche, Universitá di Parma, Via G.P. Usberti 7/a, 43124 Parma, Italy.,INFN, Sezione di Milano Bicocca, Gruppo Collegato di Parma, Parco Area delle Scienze, 7/A, 43124 Parma, Italy
| | - Raffaella Burioni
- Dipartimento di Scienze Matematiche, Fisiche ed Informatiche, Universitá di Parma, Via G.P. Usberti 7/a, 43124 Parma, Italy.,INFN, Sezione di Milano Bicocca, Gruppo Collegato di Parma, Parco Area delle Scienze, 7/A, 43124 Parma, Italy
| | - Marc Timme
- Network Dynamics, Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Faßberg, 37077 Göttingen, Germany.,Department of Physics, University of Darmstadt, 64289 Darmstadt, Germany.,Institute for Theoretical Physics, Technical University of Dresden, 01062 Dresden, Germany
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30
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Super-Coulombic atom-atom interactions in hyperbolic media. Nat Commun 2017; 8:14144. [PMID: 28120826 PMCID: PMC5288497 DOI: 10.1038/ncomms14144] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 11/07/2016] [Indexed: 11/08/2022] Open
Abstract
Dipole-dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon-polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.
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31
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Lechner W, Hauke P, Zoller P. A quantum annealing architecture with all-to-all connectivity from local interactions. SCIENCE ADVANCES 2015; 1:e1500838. [PMID: 26601316 PMCID: PMC4646830 DOI: 10.1126/sciadv.1500838] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/15/2015] [Indexed: 05/02/2023]
Abstract
Quantum annealers are physical devices that aim at solving NP-complete optimization problems by exploiting quantum mechanics. The basic principle of quantum annealing is to encode the optimization problem in Ising interactions between quantum bits (qubits). A fundamental challenge in building a fully programmable quantum annealer is the competing requirements of full controllable all-to-all connectivity and the quasi-locality of the interactions between physical qubits. We present a scalable architecture with full connectivity, which can be implemented with local interactions only. The input of the optimization problem is encoded in local fields acting on an extended set of physical qubits. The output is-in the spirit of topological quantum memories-redundantly encoded in the physical qubits, resulting in an intrinsic fault tolerance. Our model can be understood as a lattice gauge theory, where long-range interactions are mediated by gauge constraints. The architecture can be realized on various platforms with local controllability, including superconducting qubits, NV-centers, quantum dots, and atomic systems.
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Affiliation(s)
- Wolfgang Lechner
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
- Corresponding author. E-mail:
| | - Philipp Hauke
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
| | - Peter Zoller
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, 6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
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32
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Wang Y, Zhang X, Corcovilos TA, Kumar A, Weiss DS. Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice. PHYSICAL REVIEW LETTERS 2015; 115:043003. [PMID: 26252680 DOI: 10.1103/physrevlett.115.043003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 06/04/2023]
Abstract
We demonstrate arbitrary coherent addressing of individual neutral atoms in a 5×5×5 array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in nontargeted atoms is smaller than 3×10^{-3} in state fidelity. This is an important step along the path of converting the scalability promise of neutral atoms into reality.
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Affiliation(s)
- Yang Wang
- Physics Department, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA
| | - Xianli Zhang
- Physics Department, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA
| | - Theodore A Corcovilos
- Physics Department, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA
| | - Aishwarya Kumar
- Physics Department, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA
| | - David S Weiss
- Physics Department, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802, USA
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Wang F, Wang Y, Liu R, Chen D, Zhang P, Gao H, Li F. Demonstration of quantum permutation algorithm with a single photon ququart. Sci Rep 2015; 5:10995. [PMID: 26047053 PMCID: PMC4603781 DOI: 10.1038/srep10995] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/11/2015] [Indexed: 12/03/2022] Open
Abstract
We report an experiment to demonstrate a quantum permutation determining algorithm with linear optical system. By employing photon's polarization and spatial mode, we realize the quantum ququart states and all the essential permutation transformations. The quantum permutation determining algorithm displays the speedup of quantum algorithm by determining the parity of the permutation in only one step of evaluation compared with two for classical algorithm. This experiment is accomplished in single photon level and the method exhibits universality in high-dimensional quantum computation.
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Affiliation(s)
- Feiran Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yunlong Wang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Ruifeng Liu
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Dongxu Chen
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Pei Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Hong Gao
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Fuli Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, and Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049, China
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Campostrini M, Nespolo J, Pelissetto A, Vicari E. Finite-size scaling at the first-order quantum transitions of quantum Potts chains. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:052103. [PMID: 26066115 DOI: 10.1103/physreve.91.052103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Indexed: 06/04/2023]
Abstract
We investigate finite-size effects at first-order quantum transitions. For this purpose we consider the one-dimensional q-state quantum Potts chain, in particular with q=10, which undergoes a first-order transition, separating the quantum disordered and ordered phases with a discontinuity in the energy density of the ground state. In agreement with the general theory, around the transition the low-energy properties show finite-size scaling with respect to appropriate scaling variables. Their size dependence is particularly sensitive to boundary conditions, which is a specific feature of first-order quantum transitions. Finally, we also discuss the finite-size behavior of the q-state Potts model (q≥2) at the first-order transitions driven by a parallel magnetic field, occurring in the ferromagnetic phase.
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Affiliation(s)
- Massimo Campostrini
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Jacopo Nespolo
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Andrea Pelissetto
- Dipartimento di Fisica di "Sapienza," Università di Roma and INFN, Sezione di Roma I, I-00185 Roma, Italy
| | - Ettore Vicari
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
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35
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Campostrini M, Pelissetto A, Vicari E. Quantum transitions driven by one-bond defects in quantum Ising rings. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:042123. [PMID: 25974454 DOI: 10.1103/physreve.91.042123] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 06/04/2023]
Abstract
We investigate quantum scaling phenomena driven by lower-dimensional defects in quantum Ising-like models. We consider quantum Ising rings in the presence of a bond defect. In the ordered phase, the system undergoes a quantum transition driven by the bond defect between a magnet phase, in which the gap decreases exponentially with increasing size, and a kink phase, in which the gap decreases instead with a power of the size. Close to the transition, the system shows a universal scaling behavior, which we characterize by computing, either analytically or numerically, scaling functions for the low-level energy differences and the two-point correlation function. We discuss the implications of these results for the nonequilibrium dynamics in the presence of a slowly varying parallel magnetic field h, when going across the first-order quantum transition at h=0.
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Affiliation(s)
- Massimo Campostrini
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
| | - Andrea Pelissetto
- Dipartimento di Fisica di "Sapienza" Università di Roma and INFN, Sezione di Roma I, I-00185 Roma, Italy
| | - Ettore Vicari
- Dipartimento di Fisica dell'Università di Pisa and INFN, Largo Pontecorvo 3, I-56127 Pisa, Italy
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36
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Beduini FA, Zielińska JA, Lucivero VG, de Icaza Astiz YA, Mitchell MW. Macroscopic quantum state analyzed particle by particle. PHYSICAL REVIEW LETTERS 2015; 114:120402. [PMID: 25860724 DOI: 10.1103/physrevlett.114.120402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Indexed: 06/04/2023]
Abstract
Macroscopic quantum phenomena, e.g., superconductivity and squeezing, are believed to result from entanglement of macroscopic numbers of particles. We report the first direct study of this kind of entanglement: we use discrete quantum tomography to reconstruct the joint quantum state of photon pairs extracted from polarization-squeezed light. Our observations confirm several predictions from spin-squeezing theory [Beduini et al., Phys. Rev. Lett. 111, 143601 (2013)], including strong entanglement and entanglement of all photon pairs within the squeezing coherence time. This photon-by-photon analysis may give insight into other macroscopic many-body systems, e.g., photon Bose-Einstein condensates.
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Affiliation(s)
- Federica A Beduini
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Joanna A Zielińska
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Vito G Lucivero
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Yannick A de Icaza Astiz
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Morgan W Mitchell
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08015 Barcelona, Spain
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37
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Drut JE, Porter WJ. Convexity of the entanglement entropy of SU(2N)-symmetric fermions with attractive interactions. PHYSICAL REVIEW LETTERS 2015; 114:050402. [PMID: 25699423 DOI: 10.1103/physrevlett.114.050402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Indexed: 06/04/2023]
Abstract
The positivity of the probability measure of attractively interacting systems of 2N-component fermions enables the derivation of an exact convexity property for the ground-state energy of such systems. Using analogous arguments, applied to path-integral expressions for the entanglement entropy derived recently, we prove nonperturbative analytic relations for the Rényi entropies of those systems. These relations are valid for all subsystem sizes, particle numbers, and dimensions, and in arbitrary external trapping potentials.
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Affiliation(s)
- Joaquín E Drut
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - William J Porter
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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38
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Inaba K, Tokunaga Y, Tamaki K, Igeta K, Yamashita M. High-fidelity cluster state generation for ultracold atoms in an optical lattice. PHYSICAL REVIEW LETTERS 2014; 112:110501. [PMID: 24702339 DOI: 10.1103/physrevlett.112.110501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Indexed: 06/03/2023]
Abstract
We propose a method for generating high-fidelity multipartite spin entanglement of ultracold atoms in an optical lattice in a short operation time with a scalable manner, which is suitable for measurement-based quantum computation. To perform the desired operations based on the perturbative spin-spin interactions, we propose to actively utilize the extra degrees of freedom (DOFs) usually neglected in the perturbative treatment but included in the Hubbard Hamiltonian of atoms, such as, (pseudo-)charge and orbital DOFs. Our method simultaneously achieves high fidelity, short operation time, and scalability by overcoming the following fundamental problem: enhancing the interaction strength for shortening the operation time breaks the perturbative condition of the interaction and inevitably induces unwanted correlations among the spin and extra DOFs.
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Affiliation(s)
- Kensuke Inaba
- NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198, Japan and JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Yuuki Tokunaga
- NTT Secure Platform Laboratories, NTT Corporation, Musashino 180-8585, Japan and JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Kiyoshi Tamaki
- NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198, Japan and JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Kazuhiro Igeta
- NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198, Japan and JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan
| | - Makoto Yamashita
- NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198, Japan and JST, CREST, Chiyoda-ku, Tokyo 102-0075, Japan
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39
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Amico L, Aghamalyan D, Auksztol F, Crepaz H, Dumke R, Kwek LC. Superfluid qubit systems with ring shaped optical lattices. Sci Rep 2014; 4:4298. [PMID: 24599096 PMCID: PMC3944723 DOI: 10.1038/srep04298] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 02/18/2014] [Indexed: 11/09/2022] Open
Abstract
We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit.
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Affiliation(s)
- Luigi Amico
- CNR-MATIS-IMM & Dipartimento di Fisica e Astronomia, Via S. Sofia 64, 95127 Catania, Italy Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 and Institute of Advanced Studies, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616
| | - Davit Aghamalyan
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543
| | - Filip Auksztol
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 and Division of Physics and Applied Physics, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Herbert Crepaz
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 and Division of Physics and Applied Physics, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Rainer Dumke
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 and Division of Physics and Applied Physics, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Leong Chuan Kwek
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 and National Institute of Education and Institute of Advanced Studies, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616
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40
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Heilmann R, Gräfe M, Nolte S, Szameit A. Arbitrary photonic wave plate operations on chip: realizing Hadamard, Pauli-X, and rotation gates for polarisation qubits. Sci Rep 2014; 4:4118. [PMID: 24534893 PMCID: PMC3927208 DOI: 10.1038/srep04118] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 01/29/2014] [Indexed: 11/18/2022] Open
Abstract
Chip-based photonic quantum computing is an emerging technology that promises much speedup over conventional computers at small integration volumes. Particular interest is thereby given to polarisation-encoded photonic qubits, and many protocols have been developed for this encoding. However, arbitrary wave plate operation on chip are not available so far, preventing from the implementation of integrated universal quantum computing algorithms. In our work we close this gap and present Hadamard, Pauli-X, and rotation gates of high fidelity for photonic polarisation qubits on chip by employing a reorientation of the optical axis of birefringent waveguides. The optical axis of the birefringent waveguide is rotated due to the impact of an artificial stress field created by an additional modification close to the waveguide. By adjusting this length of the defect along the waveguide, the retardation between ordinary and extraordinary field components is precisely tunable including half-wave plate and quarter-wave plate operations. Our approach demonstrates the full range control of orientation and strength of the induced birefringence and thus allows arbitrary wave plate operations without affecting the degree of polarisation or introducing additional losses to the waveguides. The implemented gates are tested with classical and quantum light.
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Affiliation(s)
- René Heilmann
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Markus Gräfe
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Stefan Nolte
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - Alexander Szameit
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
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41
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Kim H, Han HS, Cho D. Magic polarization for optical trapping of atoms without Stark-induced dephasing. PHYSICAL REVIEW LETTERS 2013; 111:243004. [PMID: 24483653 DOI: 10.1103/physrevlett.111.243004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Indexed: 06/03/2023]
Abstract
We demonstrate that the differential ac-Stark shift of a Zeeman-sensitive ground hyperfine transition in an optical trap can be eliminated by using properly polarized trapping light. We use the vector polarizability of an alkali-metal atom to produce a polarization-dependent ac-Stark shift that resembles a Zeeman shift. We study a transition from the |2S1/2,F=2,mF=-2> to the |2S1/2,F=1,mF=-1> state of 7Li to observe 0.59±0.02 Hz linewidth with interrogation time of 2 s and 0.82±0.06 s coherence time of a superposition state. Implications of the narrow linewidth and the long coherence time for precision spectroscopy and quantum information processing using atoms in an optical lattice are discussed.
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Affiliation(s)
- Huidong Kim
- Department of Physics, Korea University, Seoul 136-713, Korea
| | - Hyok Sang Han
- Department of Physics, Korea University, Seoul 136-713, Korea
| | - D Cho
- Department of Physics, Korea University, Seoul 136-713, Korea
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42
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Topological states in a ladder-like optical lattice containing ultracold atoms in higher orbital bands. Nat Commun 2013; 4:1523. [PMID: 23443551 DOI: 10.1038/ncomms2523] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 01/18/2013] [Indexed: 11/08/2022] Open
Abstract
Topological insulators are classified according to their symmetries. Discovery of them in electronic solids is thus restricted by orbital and crystalline symmetries available in nature. Synthetic quantum matter, such as the recent double-well optical lattices loaded with s and p orbital ultracold atoms, can exploit symmetries and interaction beyond natural conditions. Here we unveil a topological phase of interacting fermionic atoms on a two-leg ladder derived from the above experimental optical lattice by dimension reduction. The topological band structure originates from the staggered phases of sp orbital tunnelling, requiring neither spin-orbit coupling nor other known mechanisms like p-wave pairing, artificial gauge field or rotation. Upon crossing over to two-dimensional coupled ladders, the edge modes from individual ladder form a parity-protected flat band at zero energy. Experimental signatures are found in density correlations and phase transitions to trivial band and Mott insulators.
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43
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44
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Oleś AM. Fingerprints of spin-orbital entanglement in transition metal oxides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:313201. [PMID: 22776856 DOI: 10.1088/0953-8984/24/31/313201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The concept of spin-orbital entanglement on superexchange bonds in transition metal oxides is introduced and explained on several examples. It is shown that spin-orbital entanglement in superexchange models destabilizes the long-range (spin and orbital) order and may lead either to a disordered spin-liquid state or to novel phases at low temperature which arise from strongly frustrated interactions. Such novel ground states cannot be described within the conventionally used mean field theory which separates spin and orbital degrees of freedom. Even in cases where the ground states are disentangled, spin-orbital entanglement occurs in excited states and may become crucial for a correct description of physical properties at finite temperature. As an important example of this behaviour we present spin-orbital entanglement in the RV O(3) perovskites, with R = La,Pr,…,Y b,Lu, where the finite temperature properties of these compounds can be understood only using entangled states: (i) the thermal evolution of the optical spectral weights, (ii) the dependence of the transition temperatures for the onset of orbital and magnetic order on the ionic radius in the phase diagram of the RV O(3) perovskites, and (iii) the dimerization observed in the magnon spectra for the C-type antiferromagnetic phase of Y V O(3). Finally, it is shown that joint spin-orbital excitations in an ordered phase with coexisting antiferromagnetic and alternating orbital order introduce topological constraints for the hole propagation and will thus radically modify the transport properties in doped Mott insulators where hole motion implies simultaneous spin and orbital excitations.
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Affiliation(s)
- Andrzej M Oleś
- Marian Smoluchowski Institute of Physics, Jagellonian University, Kraków, Poland.
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45
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Godsil C, Kirkland S, Severini S, Smith J. Number-theoretic nature of communication in quantum spin systems. PHYSICAL REVIEW LETTERS 2012; 109:050502. [PMID: 23006153 DOI: 10.1103/physrevlett.109.050502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Indexed: 06/01/2023]
Abstract
The last decade has witnessed substantial interest in protocols for transferring information on networks of quantum mechanical objects. A variety of control methods and network topologies have been proposed, on the basis that transfer with perfect fidelity-i.e., deterministic and without information loss-is impossible through unmodulated spin chains with more than a few particles. Solving the original problem formulated by Bose [Phys. Rev. Lett. 91, 207901 (2003)], we determine the exact number of qubits in unmodulated chains (with an XY Hamiltonian) that permit transfer with a fidelity arbitrarily close to 1, a phenomenon called pretty good state transfer. We prove that this happens if and only if the number of nodes is n = p - 1, 2p - 1, where p is a prime, or n = 2(m) - 1. The result highlights the potential of quantum spin system dynamics for reinterpreting questions about the arithmetic structure of integers and, in this case, primality.
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Affiliation(s)
- Chris Godsil
- Combinatorics & Optimization, University of Waterloo, Canada
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46
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Bowlan P, Kuehn W, Reimann K, Woerner M, Elsaesser T, Hey R, Flytzanis C. High-field transport in an electron-hole plasma: transition from ballistic to drift motion. PHYSICAL REVIEW LETTERS 2011; 107:256602. [PMID: 22243098 DOI: 10.1103/physrevlett.107.256602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Indexed: 05/31/2023]
Abstract
The time evolution of high-field carrier transport in bulk GaAs is studied with intense femtosecond THz pulses. While ballistic transport of electrons occurs in an n-type sample, a transition from ballistic to driftlike motion is observed in an electron-hole plasma. This onset of friction is due to the holes, which are heated by THz absorption. Theoretical calculations, which reproduce the data quantitatively, show that both electron-hole scattering and local-field effects in the electron-hole plasma are essential for the time-dependent friction.
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Affiliation(s)
- P Bowlan
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
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47
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Jones JA. Quantum computing with NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2011; 59:91-120. [PMID: 21742157 DOI: 10.1016/j.pnmrs.2010.11.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 11/02/2010] [Indexed: 05/31/2023]
Affiliation(s)
- Jonathan A Jones
- Centre for Quantum Computation, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
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48
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Lehman L, Zatloukal V, Brennen GK, Pachos JK, Wang Z. Quantum walks with non-Abelian anyons. PHYSICAL REVIEW LETTERS 2011; 106:230404. [PMID: 21770487 DOI: 10.1103/physrevlett.106.230404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 04/21/2011] [Indexed: 05/31/2023]
Abstract
We study the single particle dynamics of a mobile non-Abelian anyon hopping around many pinned anyons on a surface, by modeling it with a discrete time quantum walk. During the evolution, the spatial degree of freedom of the mobile anyon becomes entangled with the fusion degrees of freedom of the collective system. Each quantum trajectory makes a closed braid on the world lines of the particles establishing a direct connection between statistical dynamics and quantum link invariants. We find that asymptotically a mobile Ising model anyon becomes so entangled with its environment that its statistical dynamics reduces to a classical random walk with linear dispersion in contrast to particles with Abelian statistics which have quadratic dispersion.
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Affiliation(s)
- Lauri Lehman
- Centre for Engineered Quantum Systems, Macquarie University, Sydney, NSW, Australia
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49
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Fedorov A, Macha P, Feofanov AK, Harmans CJPM, Mooij JE. Tuned transition from quantum to classical for macroscopic quantum states. PHYSICAL REVIEW LETTERS 2011; 106:170404. [PMID: 21635021 DOI: 10.1103/physrevlett.106.170404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Indexed: 05/30/2023]
Abstract
The boundary between the classical and quantum worlds has been intensely studied. It remains fascinating to explore how far the quantum concept can reach with use of specially fabricated elements. Here we employ a tunable flux qubit with basis states having persistent currents of 1 μA carried by a million pairs of electrons. By tuning the tunnel barrier between these states we see a crossover from quantum to classical. Released from nonequilibrium, the system exhibits spontaneous coherent oscillations. For high barriers the lifetime of the states increases dramatically while the tunneling period approaches the phase coherence time and the oscillations fade away.
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Affiliation(s)
- A Fedorov
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands.
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50
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Chou CW, Hume DB, Thorpe MJ, Wineland DJ, Rosenband T. Quantum coherence between two atoms beyond Q=10(15). PHYSICAL REVIEW LETTERS 2011; 106:160801. [PMID: 21599347 DOI: 10.1103/physrevlett.106.160801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Indexed: 05/30/2023]
Abstract
We place two atoms in quantum superposition states and observe coherent phase evolution for 3.4×10(15) cycles. Correlation signals from the two atoms yield information about their relative phase even after the probe radiation has decohered. This technique allowed a frequency comparison of two (27)Al(+) ions with fractional uncertainty 3.7(-0.8)(+1.0)×10(-16)/√[τ/s]. Two measures of the Q factor are reported: The Q factor derived from quantum coherence is 3.4(-1.1)(+2.4)×10(16), and the spectroscopic Q factor for a Ramsey time of 3 s is 6.7×10(15). We demonstrate a method to detect the individual quantum states of two Al(+) ions in a Mg(+)-Al(+)-Al(+) linear ion chain without spatially resolving the ions.
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Affiliation(s)
- C W Chou
- Time and Frequency Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
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