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Universal bound on sampling bosons in linear optics and its computational implications

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National Science Review 2019年第4期6卷 719-729页

作者： man-hong yung Xun Gao Joonsuk Huh Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Central Research Institute Huawei Technologies Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua University Department of Chemistry Sungkyunkwan University

In linear optics, photons are scattered in a network through passive optical elements including beam splitters and phase shifters, leading to many intriguing applications in physics, such as Mach–Zehnder interferometry, the hong–Ou–mandel effect, and tests of fundamental quantum mechanics. Here we present the fundamental limit in the transition amplitudes of bosons, applicable to all physical linear optical networks. Apart from boson sampling, this transition bound results in many other interesting applications,including behaviors of Bose–Einstein condensates(BEC) in optical networks, counterparts of hong–Ou–mandel effects for multiple photons, and approximating permanents of matrices. In addition,this general bound implies the existence of a polynomial-time randomized algorithm for estimating the transition amplitudes of bosons, which represents a solution to an open problem raised by Aaronson and Hance(Quantum Inf Comput 2012; 14: 541–59). Consequently, this bound implies that computational decision problems encoded in linear optics, prepared and detected in the Fock basis, can be solved efficiently by classical computers within additive errors. Furthermore, our result also leads to a classical sampling algorithm that can be applied to calculate the many-body wave functions and the S-matrix of bosonic particles.

关键词： boson sampling quantum optics quantum supremacy linear optics computational complexity

Experimental study of Forrelation in nuclear spins

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Science Bulletin 2017年第7期62卷 497-502页

作者： Hang Li Xun Gao Tao Xin man-hong yung Guilu Long State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China Collaborative Innovation Centre of Quantum Matter Beijing 100084 China Centre for Quantum Information Institute for Interdisciplinary Information Sciences Tsinghua University Beijing 100084 China Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen 518055 China

Correlation functions are often employed to quantify the relationships among interdependent variables or sets of data.Recently,a new class of correlation functions,called FORRELATION,has been introduced by Aaronson and Ambainis for studying the query complexity of quantum devices.It was found that there exists a quantum query algorithm solving 2-fold FORRELATION problems with an exponential quantum speedup over all possible classical means,which represents essentially the largest possible separation between quantum and classical query complexities.Here we report an experimental study probing the2-fold and 3-fold FORRELATIONS encoded in nuclear spins.The major experimental challenge is to control the spin fluctuation to within a threshold value,which is achieved by developing a set of optimized GRAPE pulse sequences.Overall,our small-scale implementation indicates that the quantum query algorithm is capable of determining the values of FORRELATIONS within an acceptable accuracy required for demonstrating quantum supremacy,given the current technology and in the presence of experimental noise.

关键词： Forrelation Query complexity Nuclear magnetic resonance Gradient ascent pulse engineering

Quantum speedup in adaptive boosting of binary classification

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Science China(Physics,Mechanics & Astronomy) 2021年第2期64卷 51-60页

作者： XiMing Wang YueChi Ma Min-Hsiu Hsieh man-hong yung School of Physics and Mathmatical Science Nanyang Technological UniversitySingaporeSingapore Department of Physics Southern University of Science and TechnologyShenzhen518055China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen518055China Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua UniversityBeijing100084China Center for Quantum Software and Information University of Technology SydneySydney2007Australia Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen518055China

In classical machine learning,a set of weak classifiers can be adaptively combined for improving the overall performance,a technique called adaptive boosting(or AdaBoost).However,constructing a combined classifier for a large data set is typically resource consuming.Here we propose a quantum extension of AdaBoost,demonstrating a quantum algorithm that can output the optimal strong classifier with a quadratic speedup in the number of queries of the weak classifiers.Our results also include a generalization of the standard AdaBoost to the cases where the output of each classifier may be probabilistic.We prove that the query complexity of the non-deterministic classifiers is the same as those of deterministic classifiers,which may be of independent interest to the classical machine-learning community.Additionally,once the optimal classifier is determined by our quantum algorithm,no quantum resources are further required.This fact may lead to applications on near term quantum devices.

关键词： AdaBoost quantum machine learning quantum algorithm

Low-depth optical neural networks

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Chip 2022年第1期1卷 8-13页

作者： Xiao-Ming Zhang man-hong yung Department of Physics Southern University of Science and TechnologyShen-zhen 518055China Department of Physics City University of Hong KongTat Chee AvenueKowloonHong Kong SARChina Shenzhen Institute for Quan-tum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShen-zhen 518055China Shenzhen Key Laboratory of Quantum Science and En-gineering Southern University of Science and TechnologyShenzhen518055China

Optical neural network(ONNs)are emerging as attractive propos-als for machine-learning applications.However,the stability of ONNs decreases with the circuit depth,limiting the scalability of ONNs for practical uses.Here we demonstrate how to compress the circuit depth to scale only logarithmically in terms of the dimension of the data,leading to an exponential gain in terms of noise robustness.Our low-depth(LD)-ONN is based on an architecture,called Optical Com-puTing Of dot-Product UnitS(OCTOPUS),which can also be applied individually as a linear perceptron for solving classification problems.We present both numerical and theoretical evidence showing that LD-ONN can exhibit a significant improvement on robustness,compared with previous ONN proposals based on singular-value decomposition.

关键词： optical neural networks photonic chip machine learning

Noisy intermediate-scale quantum computers

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Frontiers of physics 2023年第2期18卷 1-62页

作者： Bin Cheng Xiu-Hao Deng Xiu Gu Yu He Guangchong Hu Peihao Huang Jun Li Ben-Chuan Lin Dawei Lu Yao Lu Chudan Qiu Hui Wang Tao Xin Shi Yu man-hong yung Junkai Zeng Song Zhang Youpeng Zhong Xinhua Peng Franco Nori Dapeng Yu Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China International Quantum Academy Shenzhen 518048China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of ChinaHefei 230026China Quantum Computing Center and Cluster for Pioneering Research RIKENWakoshiSaitama 351-0198Japan Physics Department University of MichiganAnn ArborMI 48109-1040USA

Quantum computers have made extraordinary progress over the past decade,and significant milestones have been achieved along the path of pursuing universal fault-tolerant quantum computers.Quantum advantage,the tipping point heralding the quantum era,has been accomplished along with several waves of breakthroughs.Quantum hardware has become more integrated and architectural compared to its toddler days.The controlling precision of various physical systems is pushed beyond the fault-tolerant threshold.Meanwhile,quantum computation research has established a new norm by embracing industrialization and commercialization.The joint power of governments,private investors,and tech companies has significantly shaped a new vibrant environment that accelerates the development of this field,now at the beginning of the noisy intermediate-scale quantum era.Here,we first discuss the progress achieved in the field of quantum computation by reviewing the most important algorithms and advances in the most promising technical routes,and then summarizing the next-stage challenges.Furthermore,we illustrate our confidence that solid foundations have been built for the fault-tolerant quantum computer and our optimism that the emergence of quantum killer applications essential for human society shall happen in the future.

关键词： quantum computer quantum algorithm quantum chip

Simulation of molecular spectroscopy with circuit quantum electrodynamics

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Science Bulletin 2018年第5期63卷 293-299页

作者： Ling Hu Yue-Chi Ma Yuan Xu Wei-Ting Wang Yu-Wei Ma Ke Liu Hai-Yan Wang Yi-Pu Song man-hong yung Lu-Yan Sun Center for Quantum Information Institute for Interdisciplinary Information Sciences Tsinghua University Beijing 100084 China institute for Quantum-Science and Engineering and Department of Physics South University of Science and Technology of China Shenzhen 518055 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen 518055 China

Spectroscopy is a crucial laboratory technique for understanding quantum systems through their interactions with the electromagnetic radiation.Particularly,spectroscopy is capable of revealing the physical structure of molecules,leading to the development of the maser—the forerunner of the laser.However,real-world applications of molecular spectroscopy are mostly confined to equilibrium states,due to computational and technological constraints;a potential breakthrough can be achieved by utilizing the emerging technology of quantum simulation.Here we experimentally demonstrate through a toy model,a superconducting quantum simulator capable of generating molecular spectra for both equilibrium and non-equilibrium states,reliably producing the vibronic structure of diatomic molecules.Furthermore,our quantum simulator is applicable not only to molecules with a wide range of electronic-vibronic coupling strength,characterized by the Huang-Rhys parameter,but also to molecular spectra not readily accessible under normal laboratory conditions.These results point to a new direction for predicting and understanding molecular spectroscopy,exploiting the power of quantum simulation.

关键词： Molecular spectroscopy Circuit quantum electrodynamics Correlation function Huang-Rhys parameter

Experimental verification of group non-membership in optical circuits

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Photonics Research 2021年第9期9卷 1745-1751页

作者： KAI SUN ZI-JIAN ZHANG FEI MENG BIN CHENG ZHU CAO JIN-SHI XU man-hong yung CHUAN-FENG LI GUANG-CAN GUO CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Department of Computer Science The University of Hong KongPokfulamHong Kong SARChina Centre for Quantum Software and Information Faculty of Engineering and Information TechnologyUniversity of Technology SydneySydneyNSW 2007Australia Key Laboratory of Advanced Control and Optimization for Chemical Processes of Ministry of Education East China University of Science and TechnologyShanghai 200237China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

The class quantum Merlin–Arthur(QMA),as the quantum analog of nondeterministic polynomial time,contains the decision problems whose YES instance can be verified efficiently with a quantum computer.The problem of deciding the group non-membership(GNM)of a group element is conjectured to be a member of QMA.Previous works on the verification of GNM,which still lacks experimental demonstration,required a quantum circuit with O(n~5)group oracle calls.Here,we provide an efficient way to verify GNM problems,in which each quantum circuit only contains O(1)group of oracle calls,and the number of qubits in each circuit is reduced by half.Based on this protocol,we then experimentally demonstrate the new verification process with a four-element group in an all-optical circuit.The new protocol is validated experimentally by observing a significant completeness-soundness gap between the probabilities of accepting elements in and outside the subgroup.This work efficiently simplifies the verification of GNM and is helpful in constructing more quantum protocols based on the near-term quantum devices.

关键词： quantum element polynomial

Plug-and-Play Approach to Non-adiabatic Geometric Quantum Computation

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Plug-and-Play Approach to Non-adiabatic Geometric Quantum Co...

“If I Do not Go to Work, They Will Die!” Dual Roles of Older-Adult Personal Support Workers' Contributions During the COVID-19 Pandemic

第十八届全国量子光学学术会议

作者：刘宝杰 Xue-Ke Song Zheng-Yuan Xue Xin Wang man-hong yung 南方科技大学 Institute for Quantum Science and Engineering and Department of PhysicsSouthern University of Science and Technology Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication EngineeringSouth China Normal University Department of Physics City University of Hong KongTat Chee AvenueKowloonHong Kong SARChinaand City University of Hong Kong Shenzhen Research Institute Shenzhen Key Laboratory of Quantum Science and Engineering

Geometrical phases acquired in cyclic quantum evolutions can be utilized as natural resources for constructing robust logic gates for quantum information processing, which was originally proposed through adiabatic changes of the driving Hamiltonian. Practically, much efforts have been made to shorten the construction times of geometrical gates, known as non-adiabatic holonomic quantum computation（NHQC）. However, previous NHQC gates require the driving Hamiltonian to satisfy a set of rather restrictive conditions, reducing the robustness of the resulting geometric gates against control errors. Here we show that non-adiabatic geometric gates can be constructed in an alternative way where the driving Hamiltonian can exhibit a high degree of flexibility for retaining the robustness of the geometric phases. Consequently, this approach makes it possible to incorporate most of the existing optimal control methods, such as dynamical decoupling, composite pulses, and shortcut to adiabaticity, into the construction of geometrical gates, to further address different types of errors. Furthermore, this extensible approach of geometric quantum computation can be applied to various physical platform such as superconducting qubits and nitrogen-vacancy（NV） centers. Specifically, we performed numerical simulation to show how the noise robustness in the recent experimental implementations [Phys. Rev. Lett. 119, 140503（2017）] and [Nat. Photonics 11, 309（2017）] of NHQC with NV centers can be significantly improved by our optimized NHQC approach. These results cover a large class of new techniques combing the noise robustness of both geometric phase and optimal control theory. Recently, a restricted form of NHQC+STA has already been demonstrated experimentally, using only three energy levels of a superconducting qubit, where the theoretical proposal was contributed by the first and last authors of this work.

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International Journal of Disaster Risk Science 2024年第2期15卷 226-238页

作者： Haorui Wu mandy yung School of Social Work Faculty of Health Dalhousie University

When COVID-19 devastated older-adult organizations(long-term care homes and retirement homes), most public attention was directed toward the older-adult residents rather than their service providers. This was especially true in the case of personal support workers, some of whom are over the age of 55, putting them in two separate categories in the COVID-19 settings:(1) a vulnerable and marginalized group who are disproportionately impacted by COVID-19; and(2) essential healthcare workers. Since the current disaster-driven research, practice, and policy have primarily focused on generalized assumptions that older-adults are a vulnerable, passive, and dependent group rather than recognizing their diversity, expertise, assets, and experiences, this study aimed to identify their contributions from the perspective of older-adult personal support worker(OAPSW). This qualitative study conducted in-depth interviews, inviting 15 OAPSWs from the Greater Toronto Area, Canada. This study uncovered the OAPSWs' contribution at three levels: individual(enhancing physical health, mental health, and overall well-being), work(improving working environment and service and supporting co-workers), and family(protecting their nuclear and extended families). The outcomes inform the older-adult research, practice, policy, public discourse, and education by enhancing the appreciation of older-adults' diverse strengths and promoting their engagement and contributions in disaster settings.

关键词： Canada COVID-19 Individual-work-family triangulation Older-adult personal support workers