Showing papers by "Qiongyi He published in 2022"
TL;DR: Recent progress and future possibilities for EPR steering are presented in this paper , highlighting practical applications and experimental aspects in multipartite, high-dimensional, and atomic and macroscopic systems.
Abstract: Recent progress and future possibilities for EPR steering are presented, highlighting practical applications and experimental aspects in multipartite, high-dimensional, and atomic and macroscopic systems.
15 citations
TL;DR: In this paper , the authors investigated the shareability of generated Wigner negativity in the multipartite scenario from a quantitative perspective, and established a monogamy relation akin to the generalized Coffman-Kundu-Wootters inequality.
Abstract: Wigner negativity, as a well-known indicator of nonclassicality, plays an essential role in quantum computing and simulation using continuous-variable systems. Recently, it has been proven that Einstein-Podolsky-Rosen steering is a prerequisite to generate Wigner negativity between two remote modes. Motivated by the demand of real-world quantum network, here we investigate the shareability of generated Wigner negativity in the multipartite scenario from a quantitative perspective. By establishing a monogamy relation akin to the generalized Coffman-Kundu-Wootters inequality, we show that the amount of Wigner negativity cannot be freely distributed among different modes. Moreover, for photon subtraction -- one of the main experimentally realized non-Gaussian operations -- we provide a general method to quantify the remotely generated Wigner negativity. With this method, we find that there is no direct quantitative relation between the Gaussian steerability and the amount of generated Wigner negativity. Our results pave the way for exploiting Wigner negativity as a valuable resource for numerous quantum information protocols based on non-Gaussian scenario.
10 citations
TL;DR: In this article , a coherent switch of optomechanical entanglement in an optical whispering-gallery-mode resonator was achieved by tuning the phase difference of the driving lasers, and the two-mode quantum squeezing can be well tuned in a highly asymmetric way, providing an efficient way to protect and enhance quantum entenglement against optical backscattering.
Abstract: Quantum entanglement plays a key role in both understanding the fundamental aspects of quantum physics and realizing various quantum devices for practical applications. Here we propose how to achieve a coherent switch of optomechanical entanglement in an optical whispering-gallery-mode resonator, by tuning the phase difference of the driving lasers. We find that the optomechanical entanglement and the associated two-mode quantum squeezing can be well tuned in a highly asymmetric way, providing an efficient way to protect and enhance quantum entanglement against optical backscattering, in comparison with conventional symmetric devices. Our findings shed a new light on improving the performance of various quantum devices in the practical noisy environment, which is crucial in such a wide range of applications as noise-tolerant quantum processing and the backscattering-immune quantum metrology.
7 citations
TL;DR: In this article , an optical non-Gaussian state with negative Wigner function at a remote node via local nonGaussian operation and shared Gaussian entangled state existing quantum steering is presented.
Abstract: Non-Gaussian states with Wigner negativity are of particular interest in quantum technology due to their potential applications in quantum computing and quantum metrology. However, how to create such states at a remote location remains a challenge, which is important for efficiently distributing quantum resource between distant nodes in a network. Here, we experimentally prepare an optical non-Gaussian state with negative Wigner function at a remote node via local non-Gaussian operation and shared Gaussian entangled state existing quantum steering. By performing photon subtraction on one mode, Wigner negativity is created in the remote target mode. We show that the Wigner negativity is sensitive to loss on the target mode, but robust to loss on the mode performing photon subtraction. This experiment confirms the connection between the remotely created Wigner negativity and quantum steering. As an application, we present that the generated non-Gaussian state exhibits metrological power in quantum phase estimation.
7 citations
TL;DR: In this paper , the authors investigated the shareability of generated Wigner negativity in the multipartite scenario from a quantitative perspective, and established a monogamy relation akin to the generalized Coffman-Kundu-Wootters inequality.
Abstract: Wigner negativity, as a well-known indicator of nonclassicality, plays an essential role in quantum computing and simulation using continuous-variable systems. Recently, it has been proven that Einstein-Podolsky-Rosen steering is a prerequisite to generate Wigner negativity between two remote modes. Motivated by the demand of real-world quantum network, here we investigate the shareability of generated Wigner negativity in the multipartite scenario from a quantitative perspective. By establishing a monogamy relation akin to the generalized Coffman-Kundu-Wootters inequality, we show that the amount of Wigner negativity cannot be freely distributed among different modes. Moreover, for photon subtraction -- one of the main experimentally realized non-Gaussian operations -- we provide a general method to quantify the remotely generated Wigner negativity. With this method, we find that there is no direct quantitative relation between the Gaussian steerability and the amount of generated Wigner negativity. Our results pave the way for exploiting Wigner negativity as a valuable resource for numerous quantum information protocols based on non-Gaussian scenario.
6 citations
09 Aug 2022
TL;DR: In this article , a generalization of the Covariance Matrix Criterion (CMC) for determining the Schmidt number of a bipartite system is presented. But the CMC criterion does not consider covariances of collective observables.
Abstract: High-dimensional entanglement has been identified as an important resource in quantum information pro-cessing, and also as a main obstacle for simulating quantum systems. Its certification is often di ffi cult, and most widely used methods for experiment are based on fidelity measurements with respect to highly entangled states. Here, instead, we consider covariances of collective observables, as in the well-known Covariance Matrix Criterion (CMC) [1] and present a generalization of the CMC criterion for determining the Schmidt number of a bipartite system. This is potentially particularly advantageous in many-body systems, such as cold atoms, where the set of practical measurements is very limited and only variances of collective operators can typically be estimated. To show the practical relevance of our results, we derive simpler Schmidt-number criteria that require similar information as the fidelity-based witnesses, yet can detect a wider set of states. We also consider case-study criteria based on three orthogonal local spin covariances, which would unlock experimentally feasi-ble detection of high-dimensional entanglement in cold atom systems. In that case, we are able to derive criteria that are valid for mixtures of states with the same Schmidt bases.
5 citations
TL;DR: In this article , the dimensionality of entanglement with the use of correlations between measurements in randomized directions has been investigated, and the covariance matrix criterion has been used to find regions in the space of moments of randomized correlations.
Abstract: We consider the problem of detecting the dimensionality of entanglement with the use of correlations between measurements in randomized directions. First, exploiting the recently derived covariance matrix criterion for the entanglement dimensionality [S. Liu \textit{et al.}, arXiv:2208.04909], we derive an inequality that resembles well-known entanglement criteria, but contains different bounds for the different dimensionalities of entanglement. This criterion is invariant under local unitary operations and can be used to find regions in the space of moments of randomized correlations. After implementing such an algorithm in practical cases, we show that it detects strictly more states than the other entanglement-dimensionality criteria available in literature, thus providing a method that is both very powerful and potentially simpler in practical scenarios. We conclude by discussing the implementation of our method in the multipartite scenario and its potential applications.
3 citations
TL;DR: In this article , the dimensionality of entanglement with the use of correlations between measurements in randomized directions has been investigated, and the covariance matrix criterion has been used to find regions in the space of moments of randomized correlations.
Abstract: We consider the problem of detecting the dimensionality of entanglement with the use of correlations between measurements in randomized directions. First, exploiting the recently derived covariance matrix criterion for the entanglement dimensionality [S. Liu \textit{et al.}, arXiv:2208.04909], we derive an inequality that resembles well-known entanglement criteria, but contains different bounds for the different dimensionalities of entanglement. This criterion is invariant under local unitary operations and can be used to find regions in the space of moments of randomized correlations. After implementing such an algorithm in practical cases, we show that it detects strictly more states than the other entanglement-dimensionality criteria available in literature, thus providing a method that is both very powerful and potentially simpler in practical scenarios. We conclude by discussing the implementation of our method in the multipartite scenario and its potential applications.
3 citations
2 citations
DOI•
TL;DR: In this paper , a class of nonlinear squeezing parameters involving accessible higher-order moments of phase-space quadratures is proposed to detect and classify multipartite non-Gaussian entanglement.
Abstract: Very recently, strongly non-Gaussian states have been observed via a direct three-mode spontaneous parametric down-conversion in a superconducting cavity [Phys. Rev. X 10, 011011 (2020)]. The created multi-photon non-Gaussian correlations are attractive and useful for various quantum information tasks. However, how to detect and classify multipartite non-Gaussian entanglement has not yet been completely understood. Here, we present an experimentally practical method to characterize continuous-variable multipartite non-Gaussian entanglement, by introducing a class of nonlinear squeezing parameters involving accessible higher-order moments of phase-space quadratures. As these parameters can depend on arbitrary operators, we consider their analytical optimization over a set of practical measurements, in order to detect different classes of multipartite non-Gaussian entanglement ranging from fully separable to fully inseparable. We demonstrate that the nonlinear squeezing parameters act as an excellent approximation to the quantum Fisher information within accessible third-order moments. The level of the nonlinear squeezing quantifies the metrological advantage provided by those entangled states. Moreover, by analyzing the above mentioned experiment, we show that our method can be readily used to confirm fully inseparable tripartite non-Gaussian entangled states by performing a limited number of measurements without requiring full knowledge of the quantum state.
1 citations
Peer Review•
27 Jul 2022
TL;DR: A brief overview of the EPR steering with emphasis on recent progress, dis-cuss current challenges, opportunities and propose various future directions can be found in this article , where the authors look to the future which directs research to a larger-scale level beyond massless and microscopic systems to reveal steering of higher dimensionality, and to build up steered networks composed of multiple parties.
Abstract: Einstein-Rosen-Podolsky (EPR) steering or quantum steering describes the “spooky-action-at-a-distance” that one party is able to remotely alter the states of the other if they share a certain entangled state. Generally, it admits an operational interpretation as the task of verifying entanglement without trust in the steering party’s devices, making it lying intermediate between Bell nonlocality and entanglement. Together with the asymmetrical nature, quantum steering has attracted a considerable interest from theoretical and experimental sides over past decades. In this Perspective, we present a brief overview of the EPR steering with emphasis on recent progress, dis-cuss current challenges, opportunities and propose various future directions. We look to the future which directs research to a larger-scale level beyond massless and microscopic systems to reveal steering of higher dimensionality, and to build up steered networks composed of multiple parties.
TL;DR: In this article , the authors considered the generation of non-classical optical quantum superpositions and investigated nonlinear quantum steering effects in NTPSD, showing that large-size Schrödinger cat states of one downconverted mode can be achieved when the other two modes are subjected to homodyne detection.
Abstract: Optical downconversion is a key resource for generating nonclassical states. Very recently, direct nondegenerate triple-photon spontaneous downconversion (NTPSD) with bright photon triplets and strong third-order correlations has been demonstrated in a superconducting device (2020 Phys. Rev. X 10 011011). Besides, linear and nonlinear tripartite entanglement in this process have also been predicted (2018 Phys. Rev. Lett. 120 043601; 2020 Phys. Rev. Lett. 125 020502). In this paper, we consider the generation of nonclassical optical quantum superpositions and investigate nonlinear quantum steering effects in NTPSD. We find that large-size Schrödinger cat states of one downconverted mode can be achieved when the other two modes are subjected to homodyne detection. Also, a two-photon Bell entangled state can be generated when only one mode is homodyned. We further reveal that such ability of remote state steering originates from nonlinear quantum steerable correlations among the triplets. This is specifically embodied by the seeming violation of the Heisenberg uncertainty relation for the inferred variances of two noncommutating higher-order quadratures of downconverted modes, based on the outcomes of homodyne detection on the other mode, i.e., nonlinear quantum steering, compared to original Einstein–Podolsky–Rosen steering. Our results demonstrate non-Gaussian nonclassical features in NTPSD and would be useful for the fundamental tests of quantum physics and implementations of optical quantum technologies.
10 Mar 2022
TL;DR: Zhang et al. as discussed by the authors proposed a method to solve the problem of quantum information in the context of nanoscience and applied it in the field of high-energy physics.
Abstract: Qiuxin Zhang‡,1 Yu Xiang‡,2 Xiaoting Gao,2 Chenhao Zhu,1 Yuxin Wang,1 Liangyu Ding,1 Xiang Zhang,1, 3 Shuaining Zhang,1, 3, ∗ Shuming Cheng,4, 5 Michael J. W. Hall,6 Qiongyi He,2, 7 and Wei Zhang1, 3, † 1Department of Physics, Renmin University of China, Beijing 100872, China 2State Key Laboratory for Mesoscopic Physics, School of Physics, Frontiers Science Center for Nano-optoelectronics, & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China 3Beijing Academy of Quantum Information Sciences, Beijing 100193, China 4The Department of Control Science and Engineering & Shanghai Institute of Intelligent Science and Technology, Tongji University, Shanghai 201804, China 5Institute for Advanced Study, Tongji University, Shanghai, 200092, China 6Department of Theoretical Physics, Research School of Physics, Australian National University, Canberra, Australian Capital Territory 0200, Australia 7Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
14 Jul 2022
TL;DR: In this paper , the authors studied the transport properties of a driven-dissipative quantum network, where multiple bosonic cavities such as photonic microcavities are coupled through a non-reciprocal bus with unidirectional transmission.
Abstract: We study the transport properties of a driven-dissipative quantum network, where multiple bosonic cavities such as photonic microcavities are coupled through a nonreciprocal bus with unidirectional transmission. For short-range coupling between the cavities, the occurrence of nonreciprocal amplification can be linked to a topological phase transition of the underlying dynamic Hamiltonian. However, for long-range coupling, we find that the nonreciprocal amplification transition deviates drastically from the topological phase transition. Nonetheless, we show that the nonreciprocal amplification transition can be connected to the emergence of zero-energy edge states of an auxiliary Hamiltonian with chiral symmetry even in the long-range coupling limit. We also investigate the stability, the crossover from short to long-range coupling, and the bandwidth of the nonreciprocal amplification. Our work has potential application in signal transmission and amplification, and also opens a window to non-Hermitian systems with long-range coupling and nontrivial boundary effects.
01 May 2022
TL;DR: In this article , a multi-path delayed-choice experiment on a large-scale integrated silicon photonic chip is described, where wave and particle nature in generalised form are characterised experimentally and the generalisation of Bohr's multipath duality relation is demonstrated.
Abstract: We report the multi-path delayed-choice experiment on a large-scale integrated silicon photonic chip. Wave- and particle-nature in generalised form are characterised experimentally and the generalisation of Bohr’s multi-path duality relation is demonstrated.
TL;DR: In this article , the authors proposed the physical interpretation of non-local quantum correlations between two systems, which can be distinguished from a single uncertainty relation derived under local hidden state (LHS)-LHS model only.
Abstract: Characterization and categorization of quantum correlations are both fundamentally and practically important in quantum information science. Although quantum correlations such as non-separability, steerability, and non-locality can be characterized by different theoretical models in different scenarios with either known (trusted) or unknown (untrusted) knowledge of the associated systems, such characterization sometimes lacks unambiguous to experimentalist. In this work, we propose the physical interpretation of nonlocal quantum correlation between two systems. In the absence of complete local description of one of the subsystems quantified by the local uncertainty relation, the correlation between subsystems becomes nonlocal. Remarkably, different nonlocal quantum correlations can be discriminated from a single uncertainty relation derived under local hidden state (LHS)-LHS model only. We experimentally characterize the two-qubit Werner state in different scenarios.
02 Nov 2022
TL;DR: In this article , a phase sensitive amplifier was proposed to accelerate the generation and control the type of non-Gaussian states (NGSs) with higher-order correlation properties in dissipative optomechanical systems.
Abstract: Non-Gaussian states (NGSs) with higher-order correlation properties have wide-range applications in quantum information processing. However, the preparation of such states with high quality still faces practical challenges. Here, we propose a protocol to rapidly generate two types of mechanical NGSs, Schr¨odinger cat states and Fock states, in dissipative optomechanical systems, even when the cooperativity is smaller than one ( g 2 /κγ < 1). In contrast to the usual scheme of directly applying non-Gaussian operations on the entangled optical mode, we show that an additional phase-sensitive amplifier can accelerate the generation and also precisely control the type of NGSs. Then, a prin-cipally deterministic multi-photon subtraction induced by the Rydberg-blockade effect is adopted to produce large-sized NGSs. The protocol can be implemented with state-of-the-art experimental systems with close to unit fidelity. Moreover, it can also be extended to generate a four-component cat state and provide new possibilities for future quantum applications of NGSs.
31 Dec 2022
TL;DR: The concept of quantum steering was originally introduced by Schrödinger to describe the "spooky action-at-a-distance" effect noted in the EPR paradox, whereby local measurements performed on one party apparently adjust (steer) the state of another distant party as discussed by the authors .
Abstract: The concept of quantum steering was originally introduced by Schrödinger to describe the "spooky action-at-a-distance" effect noted in the Einstein-Podolsky-Rosen (EPR) paradox, whereby local measurements performed on one party apparently adjust (steer) the state of another distant party. In this talk, I will give an introduction about the advances of the EPR steering and its advantage as quantum resource. Then I will present our efforts on characterizing bipartite and multipartite steering and developing its unique applications in quantum information processing. I will give an overview of our recent developments on quantum steering and its applications in quantum information. I will share our view about the current challenges, opportunities and the future directions for this topic.
30 Sep 2022
TL;DR: In this paper , the authors introduce a simple and effective method for quantifying spin-boson nonclassicality in terms of the entropy excess between the classical and the quantum Tsallis entropy.
Abstract: Spin systems interacting with boson environments are ubiquitous in nature. To what extent quantum states in such systems depart from classicality is becoming an increasingly important issue. Here, we study nonclassicality in systems involving the interaction between a spin and a boson mode. We introduce a simple and effective method for quantifying spin–boson nonclassicality in terms of the entropy excess between the classical and the quantum Tsallis entropy. The method can be naturally extended to more general systems. Fundamental properties of the nonclassicality quantifier are revealed, which render it reasonable for spin–boson states. Basic features are illustrated by a variety of typical spin–boson states. As applications, we further investigate spin–boson nonclassicality in the Dicke model, which sheds light on the normal-superradiant phase transition and quantum metrology.