推荐论文摘要

推荐论文摘要

Grover算法量子处理架构的设计与模拟

张洪涛，代永涛，凃玲英

针对混合架构经典-量子算法的量子算法处理单

元，设计基于 Grover算法的量子处理架构。将一种用

于量子计算仿真的量子程序设计语言引入 Grover量子

搜索算法中，并在Linux操作系统中进行执行与模拟。结果表明：所提架构可以提高量子搜索算法的执行性

能；利用反馈调节可以有效地实现量子搜索算法的最佳

性能。

Grover量子搜索算法；量子处理架构；量子程

序设计语言；仿真

来源出版物：华侨大学学报（自然科学版）, 2016, 37(6): 749-753

联系邮箱：张洪涛，zhanght@mail.hbut.edu.cn

量子计算复杂性理论综述

张焕国，毛少武，吴万青，等

摘要：量子计算复杂性理论是量子计算机科学的基础理论之一，对量子环境下的算法设计和问题求解具有指导意义。因此，该文对量子计算复杂性理论进行了综述。首先，介绍了各种量子图灵机模型及它们之间的关系。其次，量子计算复杂性是指在量子环境下对于某个问题求解的困难程度，包含问题复杂性、算法复杂性等。于是，该文介绍了量子问题复杂性、量子线路复杂性、量子算法复杂性，并且介绍了量子基本运算和 Shor算法的优化实现。第三，格被看做是一种具有周期性结构的n维点空间集合。格密码有很多优势，包括具有抗量子计算的潜力，格算法具有简单易实现、高效性、可并行性特点，格密码已经被证明在最坏条件下和平均条件下具有同等的安全性。因此该文介绍了格的困难问题，以及主要的格密码方案现状。最后，对今后值得研究的一些重要问题和量子计算环境下的密码设计与分析给出了展望。

关键词：量子计算；量子图灵机；量子计算复杂性；量子线路；量子环境下的密码

来源出版物：计算机学报, 2016,39(12), 2403-2428

联系邮箱：张焕国，liss@whu.edu.cn

通用量子计算机：理论、组成与实现

吴楠，宋方敏，LIXiang-Dong

摘要：通用量子计算机是指可以在不改变量子计算机物理组成和基本体系结构的条件下针对所有可计算问题进行量子计算及其它量子信息处理的设备。通用量子计算机的研究和制造具有重要的理论和实际意义。要达成制造通用量子计算机的目标，需要在底层量子物理设备、量子计算机体系结构、量子资源调度和上层量子程序设计语言、量子算法及量子应用软件等多方面进行努力。文中结合国内外在上述各方面研究的最新进展以及作者自身的研究结果，从计算机系统的角度为通用量子计算机的研究和制造绘制一幅蓝图，并详细阐述了其中的困难与努力方向。

关键词：量子计算；量子计算机；体系结构；量子信息；量子程序设计语言；量子算法；物理实现

来源出版物：计算机学报, 2016, 39(12): 2429-2445

联系邮箱：吴楠，nwu@nju.edu.cn

量子计算与量子信息简介

王帮海，龚洪波

摘要：介绍量子计算与量子信息的产生背景、发展简史，量子比特与量子门的数学描述以及它们与物理概念之间的关系。介绍量子并行基础的线性叠加、量子力学独特资源的纠缠及其应用。介绍量子密码无条件安全的理论基础、发展历史，量子信息学研究、量子计算机实现的现状，并对未来作展望。

关键词：量子计算与量子信息；发展简史；基本概念；基本特性；基本原理

来源出版物：现代计算机（上下旬）, 2015 (15): 18-22

量子计算机的概念、原理与展望

张建奋

摘要：本文介绍了量子计算机的基本概念和基本原理，追寻量子计算机的历史发展进程，并展望未来发展前景。

关键词：量子计算机；昆比特；态叠加原理；相干与退相干；量子并行；量子纠缠

来源出版物：物理通报, 2015 (4): 125-128

量子计算机工程化现状及挑战

杜世平

摘要：量子计算和量子信息研究的是用量子力学系统能够完成的信息处理任务，主要涉及量子力学、计算机科学和密码学等不同领域的科学理论。更深层次地探讨量子科学与工程技术，对于人们从本质上认识物理化学过程及生命科学等具有重要意义。介绍了量子科学技术相关研究成果，指出了当前量子科学前沿课题、量子计算机工程化难题及对策。

关键词：量子科学；量子计算；量子计算机工程化

来源出版物：软件导刊, 2015, 14(3): 13-14

量子可逆逻辑电路双向综合算法

王冬，张晓蕾，朱长江

摘要：量子可逆逻辑电路综合技术是构建量子计算机的关键技术之一。本文提出基于数组正反变换的量子可逆逻辑电路双向综合算法。该算法依据两个数字间的汉明距离，利用邻接矩阵的电路转化规则，从正反两个方向，生成任意给定置换的量子可逆逻辑电路。理论分析表明，该方法综合 n量子电路最多需要（n-1）·2n+1个扩展通用 Toffoli门。与其它同类算法相比，由于不需要穷尽搜索，该算法的时间复杂度和空间复杂度都有大幅度降低。此外，由于合理采用了扩展通用Toffoli门，该算法可综合任一置换（包括奇置换和偶置换）的量子可逆逻辑电路，且电路中量子门的数量大幅减少。

关键词：量子可逆逻辑电路；量子计算；offoli门

来源出版物：小型微型计算机系统, 2014, 35(5): 1111-1115

Error suppression for hamiltonian-based quantum computation using subsystem codes

来源出版物：Physical Review Letters, 2017, 118(3): 030504

Demonstration of a small programmable quantum computer with atomic qubits

Debnath, S; Linke, NM; Figgatt, C; et al.

Abstract: Quantum computers can solve certain problems more efficiently than any possible conventional computer. Small quantum algorithms have been demonstrated on multiple quantum computing platforms, many specifically tailored in hardware to implement a particular algorithm or execute a limited number of computational paths. Here we demonstrate a five-qubit trapped-ion quantum computer that can be programmed in software to implement arbitrary quantum algorithms by executing any sequence of universal quantum logic gates. We compile algorithms into a fully connected set of gate operations that are native to the hardware and have a mean fidelity of 98 per cent. Reconfiguring these gate sequences provides the flexibility to implement a variety of algorithms without altering the hardware. As examples, we implement the Deutsch–Jozsa and Bernstein–Vazirani algorithms with average success rates of 95 and 90 per cent, respectively. We also perform a coherent quantum Fourier transform on five trapped-ion qubits for phase estimation and period finding with average fidelities of 62 and 84 per cent, respectively. This small quantum computer can be scaled to larger numbers of qubits within a single register, and can be further expanded by connecting several such modules through ion shuttling or photonic quantum channels.

来源出版物：Nature, 2016, 536(7614): 63-66

联系邮箱：Debnath; sdebnath@umd.edu

Digitized adiabatic quantum computing with a superconducting circuit

Barends, R; Shabani, A; Lamata, L; et al.

Abstract: Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.

来源出版物：Nature, 2016, 534(7606): 222-226

联系邮箱：Barends, R; barends@google.com

Computational multiqubit tunnelling in programmable quantum annealers

Boixo, S; Smelyanskiy, VN; Shabani, A; et al.

Abstract: Quantum tunnelling is a phenomenon in which a quantum state traverses energy barriers higher than the energy of the state itself. Quantum tunnelling has been hypothesized as an advantageous physical resource for optimization in quantum annealing. However, computational multiqubit tunnelling has not yet been observed, and a theory of co-tunnelling under high-and low-frequency noises is lacking. Here we show that 8-qubit tunnelling plays a computational role in a currently available programmable quantum annealer. We devise a probe for tunnelling, a computational primitive where classical paths are trapped in a false minimum. In support of the design of quantum annealers we develop a nonperturbative theory of open quantum dynamics under realistic noise characteristics. This theory accurately predicts the rate of many-body dissipative quantum tunnelling subject to the polaron effect. Furthermore, we experimentally demonstrate that quantum tunnelling outperforms thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive.

来源出版物：Nature Communications, 2016, 7, 10327

联系邮箱：Boixo, S; boixo@google.com

Real-time dynamics of lattice gauge theories with a few-qubit quantum computer

Martinez, EA; Muschik, CA; Schindler, P; et al.

Abstract: Gauge theories are fundamental to our understanding of interactions between the elementary constituents of matter as mediated by gauge bosons. However, computing the real-time dynamics in gauge theories is a notorious challenge for classical computational methods. This has recently stimulated theoretical effort, using Feynman’s idea of a quantum simulator, to devise schemes for simulating such theories on engineered quantum-mechanical devices, with the difficulty that gauge invariance and the associated local conservation laws (Gauss laws) need to be implemented. Here we report the experimental demonstration of a digital quantum simulation of a lattice gauge theory, by realizing (1+1)-dimensional quantum electrodynamics (the Schwinger model) on a few-qubit trapped-ion quantum computer. We are interested in the real-time evolution of the Schwinger mechanism, describing the instability of the bare vacuum due to quantum fluctuations, which manifests itself in the spontaneous creation of electron–positron pairs. To make efficient use of our quantum resources, we map the original problem to a spin model by eliminating the gauge fields in favour of exotic long-range interactions, which can be directly and efficiently implemented on anion trap architecture. We explore the Schwinger mechanism of particle–antiparticle generation by monitoring the mass production and the vacuum persistence amplitude. Moreover, we track the real-time evolution of entanglement in the system, which illustrates how particle creation and entanglement generation are directly related. Our work represents a first step towards quantum simulation of high-energy theories using atomic physics experiments—the long-term intention is to extend this approach to real-time quantum simulations of non-Abelian lattice gauge theories.

来源出版物：Nature, 2016, 534(7608): 516-519

联系邮箱：Martinez, EA; esteban.martinez@uibk.ac.at

Ground state blind quantum computation on AKLT state

Morimae, T; Dunjko, V; Kashefi, E

Abstract: The blind quantum computing protocols (BQC) enable a classical client with limited quantum technology to delegate a computation to the quantum server (s) in such a way that the privacy of the computation is preserved. Here we present a new scheme for BQC that uses the concept of the measurement based quantum computing with the novel resource state of Affleck-Kennedy-Lieb-Tasaki (AKLT) chains leading to more robust computation. AKLT states are physically motivated resource as they are gapped ground states of a physically natural Hamiltonian in condensed matter physics. Our BQC protocol can enjoy the advantages of AKLT resource states, such as the cooling preparation of the resource state, the energy-gap protection of the quantum computation, and the simple and efficient preparation of the resource state in linear optics with biphotons.

关键词：delegated quantum computing; measurement

based quantum computing; AKLT model

来源出版物：Quantum Information & Computation, 2015,

15 (3-4): 200-234

联系邮箱：Morimae, T; morimae@gmail.com

Cryogenic control architecture for large-scale quantum computing

Hornibrook, JM; Colless, JI; Lamb, IDC; et al.

Abstract: Solid-state qubits have recently advanced to the level that enables them, in principle, to be scaled up into fault-tolerant quantum computers. As these physical qubits continue to advance, meeting the challenge of realizing a quantum machine will also require the development of new supporting devices and control architectures with complexity far beyond the systems used in today’s fewqubit experiments. Here, we report a microarchitecture for controlling and reading out qubits during the execution of a quantum algorithm such as an error-correcting code. We demonstrate the basic principles of this architecture using a cryogenic switch matrix implemented via high-electronmobility transistors and a new kind of semiconductor device based on gate-switchable capacitance. The switch matrix is used to route microwave waveforms to qubits under the control of a field-programmable gate array, also operating at cryogenic temperatures. Taken together, these results suggest a viable approach for controlling large-scale quantum systems using semi- conductor technology.

来源出版物：Physical Review Applied, 2015, 3(2): 024010联系邮箱：Reilly, DJ; david.reilly@sydney.edu.au

Wigner function negativity and contextuality in quantum computation on rebits

Delfosse, N; Guerin, PA; Bian, J

Abstract: We describe a universal scheme of quantum computation by state injection on rebits (states with real density matrices). For this scheme, we establish contextuality and Wigner function negativity as computational resources, extending results of M. Howard et al. to two-level systems. For this purpose, we define a Wigner function suited to systems of n rebits and prove a corresponding discrete Hudson’s theorem. We introduce contextuality witnesses for rebit states and discuss the compatibility of our result with state-independent contextuality.

来源出版物：Physical Review X, 2015, 5(2): 021003

Contextuality supplies the ‘magic’ for quantum computation

Howard, M; Wallman, J; Veitch, V; et al.

Abstract: Quantum computers promise dramatic advantages over their classical counterparts, but the source of the power in quantum computing has remained elusive. Here we prove a remarkable equivalence betweenthe onset of contextuality and the possibility of universal quantum computation via ‘magic state’ distillation, which is the leading model for experimentally realizing a fault-tolerant quantum computer. This is a conceptually satisfying link, because contextuality, which precludes a simple ‘hidden variable’ model of quantum mechanics, provides one of the fundamental characterizations of uniquely quantum phenomena. Furthermore, this connection suggests a unifying paradigm for the resources of quantum information: the non-locality of quantum theory is a particular kind of contextuality, and non-locality is already known to be a critical resource for achieving advantages with quantum communication. In addition to clarifying these fundamental issues, this work advances the resource framework for quantum computation, which has a number of practical applications, such as characterizing the efficiency and trade-offs between distinct theoretical and experimental schemes for achieving robust quantum computation, and putting bounds on the overhead cost for the classical simulation of quantum algorithms.

来源出版物：Nature, 2014, 510(7505): 351-355

联系邮箱：Emerson, J; jemerson@math.uwaterloo.ca

Quantum computations on a topologically encoded qubit

Nigg, D; Muller, M; Martinez, EA; et al.

Abstract: The construction of a quantum computer remains a fundamental scientific and technological challenge because of the influence of unavoidable noise. Quantum states and operations can be protected from errors through the use of protocols for quantum computing with faulty components. We present a quantum error-correcting code in which one qubit is encoded in entangled states distributed over seven trapped-ion qubits. The code can detect one bit flip error, one phase flip error, or a combined error of both, regardless on which of the qubits they occur. We applied sequences of gate operations on the encoded qubit to explore its computational capabilities. This seven-qubit code represents a fully functional instance of a topologically encoded qubit, or color code, and opens a route toward fault-tolerant quantum computing.

来源出版物：Science, 2014, 345(6194): 302-305

联系邮箱：Nigg, D; daniel.nigg@uibk.ac.at

编辑：王微

Marvian, M; Lidar, DA

We present general conditions for quantum error suppression for Hamiltonian-based quantum computation using subsystem codes. This involves encoding the Hamiltonian performing the computation using an error detecting subsystem code and the addition of a penalty term that commutes with the encoded Hamiltonian. The scheme is general and includes the stabilizer formalism of both subspace and subsystem codes as special cases. We derive performance bounds and show that complete error suppression results in the large penalty limit. To illustrate the power of subsystem-based error suppression, we introduce fully two-local constructions for protection against local errors of the swap gate of adiabatic gate teleportation and the Ising chain in a transverse field.