1
|
Busnaina JH, Shi Z, McDonald A, Dubyna D, Nsanzineza I, Hung JSC, Chang CWS, Clerk AA, Wilson CM. Quantum simulation of the bosonic Kitaev chain. Nat Commun 2024; 15:3065. [PMID: 38594258 PMCID: PMC11004022 DOI: 10.1038/s41467-024-47186-8] [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: 09/22/2023] [Accepted: 03/22/2024] [Indexed: 04/11/2024] Open
Abstract
Superconducting quantum circuits are a natural platform for quantum simulations of a wide variety of important lattice models describing topological phenomena, spanning condensed matter and high-energy physics. One such model is the bosonic analog of the well-known fermionic Kitaev chain, a 1D tight-binding model with both nearest-neighbor hopping and pairing terms. Despite being fully Hermitian, the bosonic Kitaev chain exhibits a number of striking features associated with non-Hermitian systems, including chiral transport and a dramatic sensitivity to boundary conditions known as the non-Hermitian skin effect. Here, using a multimode superconducting parametric cavity, we implement the bosonic Kitaev chain in synthetic dimensions. The lattice sites are mapped to frequency modes of the cavity, and the in situ tunable complex hopping and pairing terms are created by parametric pumping at the mode-difference and mode-sum frequencies, respectively. We experimentally demonstrate important precursors of nontrivial topology and the non-Hermitian skin effect in the bosonic Kitaev chain, including chiral transport, quadrature wavefunction localization, and sensitivity to boundary conditions. Our experiment is an important first step towards exploring genuine many-body non-Hermitian quantum dynamics.
Collapse
Affiliation(s)
- Jamal H Busnaina
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Zheng Shi
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Alexander McDonald
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA
- Institut quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Dmytro Dubyna
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Ibrahim Nsanzineza
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Jimmy S C Hung
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - C W Sandbo Chang
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Aashish A Clerk
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA
| | - Christopher M Wilson
- Institute for Quantum Computing and Department of Electrical & Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
| |
Collapse
|
2
|
Sayyad S, Lado JL. Transfer learning from Hermitian to non-Hermitian quantum many-body physics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:185603. [PMID: 38277690 DOI: 10.1088/1361-648x/ad22f8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/26/2024] [Indexed: 01/28/2024]
Abstract
Identifying phase boundaries of interacting systems is one of the key steps to understanding quantum many-body models. The development of various numerical and analytical methods has allowed exploring the phase diagrams of many Hermitian interacting systems. However, numerical challenges and scarcity of analytical solutions hinder obtaining phase boundaries in non-Hermitian many-body models. Recent machine learning methods have emerged as a potential strategy to learn phase boundaries from various observables without having access to the full many-body wavefunction. Here, we show that a machine learning methodology trained solely on Hermitian correlation functions allows identifying phase boundaries of non-Hermitian interacting models. These results demonstrate that Hermitian machine learning algorithms can be redeployed to non-Hermitian models without requiring further training to reveal non-Hermitian phase diagrams. Our findings establish transfer learning as a versatile strategy to leverage Hermitian physics to machine learning non-Hermitian phenomena.
Collapse
Affiliation(s)
- Sharareh Sayyad
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany
| | - Jose L Lado
- Department of Applied Physics, Aalto University, FI-00076 Aalto, Espoo, Finland
| |
Collapse
|
3
|
Wu Y, Wang Y, Ye X, Liu W, Niu Z, Duan CK, Wang Y, Rong X, Du J. Third-order exceptional line in a nitrogen-vacancy spin system. NATURE NANOTECHNOLOGY 2024; 19:160-165. [PMID: 38225359 DOI: 10.1038/s41565-023-01583-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 11/22/2023] [Indexed: 01/17/2024]
Abstract
Exceptional points (EPs) are singularities in non-Hermitian systems, where k (k ≥ 2) eigenvalues and eigenstates coalesce. High-order EPs exhibit richer topological characteristics and better sensing performance than second-order EPs. Theory predicts even richer non-Hermitian topological phases for high-order EP geometries, such as lines or rings formed entirely by high-order EPs. However, experimental exploration of high-order EP geometries has hitherto proved difficult due to the demand for more degrees of freedom in the Hamiltonian's parameter space or a higher level of symmetries. Here we observe a third-order exceptional line in an atomic-scale system. To this end, we use a nitrogen-vacancy spin in diamond and introduce multiple symmetries in the non-Hermitian Hamiltonian realized with the system. Furthermore, we show that the symmetries play an essential role in the occurrence of high-order EP geometries. Our approach can in future be further applied to explore high-order EP-related topological physics at the atomic scale and, potentially, for applications of high-order EPs in quantum technologies.
Collapse
Affiliation(s)
- Yang Wu
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
| | - Yunhan Wang
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
| | - Xiangyu Ye
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
| | - Wenquan Liu
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
- School of Science, Beijing University of Posts and Telecommunications, Beijing, China
| | - Zhibo Niu
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
| | - Chang-Kui Duan
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, China
| | - Ya Wang
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, China
| | - Xing Rong
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China.
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China.
- Hefei National Laboratory, University of Science and Technology of China, Hefei, China.
| | - Jiangfeng Du
- CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei, China.
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China.
- Hefei National Laboratory, University of Science and Technology of China, Hefei, China.
- Institute of Quantum Sensing and School of Physics, Zhejiang University, Hangzhou, China.
| |
Collapse
|
4
|
Song X, Murch K. Parity-Time Symmetric Holographic Principle. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1523. [PMID: 37998215 PMCID: PMC10670666 DOI: 10.3390/e25111523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023]
Abstract
Originating from the Hamiltonian of a single qubit system, the phenomenon of the avoided level crossing is ubiquitous in multiple branches of physics, including the Landau-Zener transition in atomic, molecular, and optical physics, the band structure of condensed matter physics and the dispersion relation of relativistic quantum physics. We revisit this fundamental phenomenon in the simple example of a spinless relativistic quantum particle traveling in (1+1)-dimensional space-time and establish its relation to a spin-1/2 system evolving under a PT-symmetric Hamiltonian. This relation allows us to simulate 1-dimensional eigenvalue problems with a single qubit. Generalizing this relation to the eigenenergy problem of a bulk system with N spatial dimensions reveals that its eigenvalue problem can be mapped onto the time evolution of the edge state with (N-1) spatial dimensions governed by a non-Hermitian Hamiltonian. In other words, the bulk eigenenergy state is encoded in the edge state as a hologram, which can be decoded by the propagation of the edge state in the temporal dimension. We argue that the evolution will be PT-symmetric as long as the bulk system admits parity symmetry. Our work finds the application of PT-symmetric and non-Hermitian physics in quantum simulation and provides insights into the fundamental symmetries.
Collapse
Affiliation(s)
| | - Kater Murch
- Department of Physics, Washington University, St. Louis, MO 63130, USA;
| |
Collapse
|
5
|
Li ZZ, Chen W, Abbasi M, Murch KW, Whaley KB. Speeding Up Entanglement Generation by Proximity to Higher-Order Exceptional Points. PHYSICAL REVIEW LETTERS 2023; 131:100202. [PMID: 37739369 DOI: 10.1103/physrevlett.131.100202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 06/29/2023] [Accepted: 08/01/2023] [Indexed: 09/24/2023]
Abstract
Entanglement is a key resource for quantum information technologies ranging from quantum sensing to quantum computing. Conventionally, the entanglement between two coupled qubits is established at the timescale of the inverse of the coupling strength. In this Letter, we study two weakly coupled non-Hermitian qubits and observe entanglement generation at a significantly shorter timescale by proximity to a higher-order exceptional point. We establish a non-Hermitian perturbation theory based on constructing a biorthogonal complete basis and further identify the optimal condition to obtain the maximally entangled state. Our study of speeding up entanglement generation in non-Hermitian quantum systems opens new avenues for harnessing coherent nonunitary dissipation for quantum technologies.
Collapse
Affiliation(s)
- Zeng-Zhao Li
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Berkeley Center for Quantum Information and Computation, Berkeley, California 94720, USA
| | - Weijian Chen
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - Maryam Abbasi
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - Kater W Murch
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - K Birgitta Whaley
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Berkeley Center for Quantum Information and Computation, Berkeley, California 94720, USA
| |
Collapse
|
6
|
Li Z, Luo XW, Lin D, Gharajeh A, Moon J, Hou J, Zhang C, Gu Q. Topological Microlaser with a Non-Hermitian Topological Bulk. PHYSICAL REVIEW LETTERS 2023; 131:023202. [PMID: 37505939 DOI: 10.1103/physrevlett.131.023202] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 05/25/2023] [Indexed: 07/30/2023]
Abstract
Bulk-edge correspondence, with quantized bulk topology leading to protected edge states, is a hallmark of topological states of matter and has been experimentally observed in electronic, atomic, photonic, and many other systems. While bulk-edge correspondence has been extensively studied in Hermitian systems, a non-Hermitian bulk could drastically modify the Hermitian topological band theory due to the interplay between non-Hermiticity and topology, and its effect on bulk-edge correspondence is still an ongoing pursuit. Importantly, including non-Hermicity can significantly expand the horizon of topological states of matter and lead to a plethora of unique properties and device applications, an example of which is a topological laser. However, the bulk topology, and thereby the bulk-edge correspondence, in existing topological edge-mode lasers is not well defined. Here, we propose and experimentally probe topological edge-mode lasing with a well-defined non-Hermitian bulk topology in a one-dimensional (1D) array of coupled ring resonators. By modeling the Hamiltonian with an additional degree of freedom (referred to as synthetic dimension), our 1D structure is equivalent to a 2D non-Hermitian Chern insulator with precise mapping. Our Letter may open a new pathway for probing non-Hermitian topological effects and exploring non-Hermitian topological device applications.
Collapse
Affiliation(s)
- Zhitong Li
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Xi-Wang Luo
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Dayang Lin
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Abouzar Gharajeh
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Jiyoung Moon
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Junpeng Hou
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Chuanwei Zhang
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Qing Gu
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| |
Collapse
|
7
|
Downing CA, Vidiella-Barranco A. Parametrically driving a quantum oscillator into exceptionality. Sci Rep 2023; 13:11004. [PMID: 37419917 PMCID: PMC10329046 DOI: 10.1038/s41598-023-37964-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/30/2023] [Indexed: 07/09/2023] Open
Abstract
The mathematical objects employed in physical theories do not always behave well. Einstein's theory of space and time allows for spacetime singularities and Van Hove singularities arise in condensed matter physics, while intensity, phase and polarization singularities pervade wave physics. Within dissipative systems governed by matrices, singularities occur at the exceptional points in parameter space whereby some eigenvalues and eigenvectors coalesce simultaneously. However, the nature of exceptional points arising in quantum systems described within an open quantum systems approach has been much less studied. Here we consider a quantum oscillator driven parametrically and subject to loss. This squeezed system exhibits an exceptional point in the dynamical equations describing its first and second moments, which acts as a borderland between two phases with distinctive physical consequences. In particular, we discuss how the populations, correlations, squeezed quadratures and optical spectra crucially depend on being above or below the exceptional point. We also remark upon the presence of a dissipative phase transition at a critical point, which is associated with the closing of the Liouvillian gap. Our results invite the experimental probing of quantum resonators under two-photon driving, and perhaps a reappraisal of exceptional and critical points within dissipative quantum systems more generally.
Collapse
Affiliation(s)
- C A Downing
- Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK.
| | - A Vidiella-Barranco
- Gleb Wataghin Institute of Physics, University of Campinas - UNICAMP, Campinas, SP, 13083-859, Brazil
| |
Collapse
|
8
|
Liang C, Tang Y, Xu AN, Liu YC. Observation of Exceptional Points in Thermal Atomic Ensembles. PHYSICAL REVIEW LETTERS 2023; 130:263601. [PMID: 37450830 DOI: 10.1103/physrevlett.130.263601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/13/2023] [Indexed: 07/18/2023]
Abstract
Exceptional points (EPs) in non-Hermitian systems have recently attracted wide interest and spawned intriguing prospects for enhanced sensing. However, EPs have not yet been realized in thermal atomic ensembles, which is one of the most important platforms for quantum sensing. Here we experimentally observe EPs in multilevel thermal atomic ensembles and realize enhanced sensing of the magnetic field for 1 order of magnitude. We take advantage of the rich energy levels of atoms and construct effective decays for selected energy levels by employing laser coupling with the excited state, yielding unbalanced decay rates for different energy levels, which finally results in the existence of EPs. Furthermore, we propose the optical polarization rotation measurement scheme to detect the splitting of the resonance peaks, which makes use of both the absorption and dispersion properties and shows an advantage with enhanced splitting compared with the conventional transmission measurement scheme. Additionally, in our system both the effective coupling strength and decay rates are flexibly adjustable, and thus the position of the EPs are tunable, which expands the measurement range. Our Letter not only provides a new controllable platform for studying EPs and non-Hermitian physics, but also provide new ideas for the design of EP-enhanced sensors and opens up realistic opportunities for practical applications in the high-precision sensing of magnetic field and other physical quantities.
Collapse
Affiliation(s)
- Chao Liang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yuanjiang Tang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - An-Ning Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yong-Chun Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
| |
Collapse
|
9
|
Saha M, Agarwalla BK, Kulkarni M, Purkayastha A. Universal Subdiffusive Behavior at Band Edges from Transfer Matrix Exceptional Points. PHYSICAL REVIEW LETTERS 2023; 130:187101. [PMID: 37204882 DOI: 10.1103/physrevlett.130.187101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 11/11/2022] [Accepted: 03/31/2023] [Indexed: 05/21/2023]
Abstract
We discover a deep connection between parity-time symmetric optical systems and quantum transport in one-dimensional fermionic chains in a two-terminal open system setting. The spectrum of one dimensional tight-binding chain with periodic on-site potential can be obtained by casting the problem in terms of 2×2 transfer matrices. We find that these non-Hermitian matrices have a symmetry exactly analogous to the parity-time symmetry of balanced-gain-loss optical systems, and hence show analogous transitions across exceptional points. We show that the exceptional points of the transfer matrix of a unit cell correspond to the band edges of the spectrum. When connected to two zero temperature baths at two ends, this consequently leads to subdiffusive scaling of conductance with system size, with an exponent 2, if the chemical potential of the baths are equal to the band edges. We further demonstrate the existence of a dissipative quantum phase transition as the chemical potential is tuned across any band edge. Remarkably, this feature is analogous to transition across a mobility edge in quasiperiodic systems. This behavior is universal, irrespective of the details of the periodic potential and the number of bands of the underlying lattice. It, however, has no analog in absence of the baths.
Collapse
Affiliation(s)
- Madhumita Saha
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Ward No. 8, NCL Colony, Pashan, Pune, Maharashtra 411008, India
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore 560089, India
| | - Bijay Kumar Agarwalla
- Department of Physics, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Ward No. 8, NCL Colony, Pashan, Pune, Maharashtra 411008, India
| | - Manas Kulkarni
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore 560089, India
| | - Archak Purkayastha
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
- Department of Physics, Indian Institute of Technology, Hyderabad 502284, India
| |
Collapse
|
10
|
Baek S, Park SH, Oh D, Lee K, Lee S, Lim H, Ha T, Park HS, Zhang S, Yang L, Min B, Kim TT. Non-Hermitian chiral degeneracy of gated graphene metasurfaces. LIGHT, SCIENCE & APPLICATIONS 2023; 12:87. [PMID: 37024464 PMCID: PMC10079968 DOI: 10.1038/s41377-023-01121-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 02/06/2023] [Accepted: 02/27/2023] [Indexed: 05/25/2023]
Abstract
Non-Hermitian degeneracies, also known as exceptional points (EPs), have been the focus of much attention due to their singular eigenvalue surface structure. Nevertheless, as pertaining to a non-Hermitian metasurface platform, the reduction of an eigenspace dimensionality at the EP has been investigated mostly in a passive repetitive manner. Here, we propose an electrical and spectral way of resolving chiral EPs and clarifying the consequences of chiral mode collapsing of a non-Hermitian gated graphene metasurface. More specifically, the measured non-Hermitian Jones matrix in parameter space enables the quantification of nonorthogonality of polarisation eigenstates and half-integer topological charges associated with a chiral EP. Interestingly, the output polarisation state can be made orthogonal to the coalesced polarisation eigenstate of the metasurface, revealing the missing dimension at the chiral EP. In addition, the maximal nonorthogonality at the chiral EP leads to a blocking of one of the cross-polarised transmission pathways and, consequently, the observation of enhanced asymmetric polarisation conversion. We anticipate that electrically controllable non-Hermitian metasurface platforms can serve as an interesting framework for the investigation of rich non-Hermitian polarisation dynamics around chiral EPs.
Collapse
Affiliation(s)
- Soojeong Baek
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Sang Hyun Park
- Department of Electrical and Computer Engineering, University of Minnesota, 200 Union street SE, Minneapolis, MN, 55455, USA
| | - Donghak Oh
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Kanghee Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
- Korea Research Institute of Standards and Science (KRISS), Gajeong-ro 267, Daejeon, 34113, Republic of Korea
| | - Sangha Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Hosub Lim
- Harvard Institute of Medicine, Harvard Medical School, Harvard University, Brigham and Women's Hospital, 25 Shattuck Street, Boston, MA, 02215, USA
| | - Taewoo Ha
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Seobu-ro 2066, Suwon, 16419, Republic of Korea
| | - Hyun Sung Park
- Samsung Advanced Institute of Technology, Samsung Electronics, Samsung-ro, Suwon, 16678, Republic of Korea
| | - Shuang Zhang
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Lan Yang
- Department of Electrical and Systems Engineering, Washington University, 1 Brookings Drive, Saint Louis, MO, 63130, USA
| | - Bumki Min
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea.
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea.
| | - Teun-Teun Kim
- Department of Physics, University of Ulsan, Daehak-ro, Ulsan, 44610, Republic of Korea.
| |
Collapse
|
11
|
Bu JT, Zhang JQ, Ding GY, Li JC, Zhang JW, Wang B, Ding WQ, Yuan WF, Chen L, Özdemir ŞK, Zhou F, Jing H, Feng M. Enhancement of Quantum Heat Engine by Encircling a Liouvillian Exceptional Point. PHYSICAL REVIEW LETTERS 2023; 130:110402. [PMID: 37001093 DOI: 10.1103/physrevlett.130.110402] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/21/2022] [Accepted: 02/21/2023] [Indexed: 06/19/2023]
Abstract
Quantum heat engines are expected to outperform the classical counterparts due to quantum coherences involved. Here we experimentally execute a single-ion quantum heat engine and demonstrate, for the first time, the dynamics and the enhanced performance of the heat engine originating from the Liouvillian exceptional points (LEPs). In addition to the topological effects related to LEPs, we focus on thermodynamic effects, which can be understood by the Landau-Zener-Stückelberg process under decoherence. We witness a positive net work from the quantum heat engine if the heat engine cycle dynamically encircles a LEP. Further investigation reveals that a larger net work is done when the system is operated closer to the LEP. We attribute the enhanced performance of the quantum heat engine to the Landau-Zener-Stückelberg process, enabled by the eigenenergy landscape in the vicinity of the LEP, and the exceptional point-induced topological transition. Therefore, our results open new possibilities toward LEP-enabled control of quantum heat engines and of thermodynamic processes in open quantum systems.
Collapse
Affiliation(s)
- J-T Bu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-Q Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - G-Y Ding
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-C Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-W Zhang
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - B Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - W-Q Ding
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - W-F Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - L Chen
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - Ş K Özdemir
- Department of Engineering Science and Mechanics, and Materials Research Institute, Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA
| | - F Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - H Jing
- Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, China
| | - M Feng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China
| |
Collapse
|
12
|
Dynamical control of quantum heat engines using exceptional points. Nat Commun 2022; 13:6225. [PMID: 36266331 DOI: 10.1038/s41467-022-33667-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 09/27/2022] [Indexed: 11/08/2022] Open
Abstract
A quantum thermal machine is an open quantum system coupled to hot and cold thermal baths. Thus, its dynamics can be well understood using the concepts and tools from non-Hermitian quantum systems. A hallmark of non-Hermiticity is the existence of exceptional points where the eigenvalues of a non-Hermitian Hamiltonian or a Liouvillian superoperator and their associated eigenvectors coalesce. Here, we report the experimental realization of a single-ion heat engine and demonstrate the effect of Liouvillian exceptional points on the dynamics and the performance of a quantum heat engine. Our experiments have revealed that operating the engine in the exact- and broken-phases, separated by a Liouvillian exceptional point, respectively during the isochoric heating and cooling strokes of an Otto cycle produces more work and output power and achieves higher efficiency than executing the Otto cycle completely in the exact phase where the system has an oscillatory dynamics and higher coherence. This result opens interesting possibilities for the control of quantum heat engines and will be of interest to other research areas that are concerned with the role of coherence and exceptional points in quantum processes and in work extraction by thermal machines.
Collapse
|