PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 12 min 5 sec ago

Noise analysis for high-fidelity quantum entangling gates in an anharmonic linear Paul trap

10 hours 16 min ago

Author(s): Yukai Wu, Sheng-Tao Wang, and L.-M. Duan

The realization of high-fidelity quantum gates in a multiqubit system, with a typical target set at 99.9%, is a critical requirement for the implementation of fault-tolerant quantum computation. To reach this level of fidelity, one needs to carefully analyze the noises and imperfections in the exper...


[Phys. Rev. A 97, 062325] Published Tue Jun 19, 2018

Categories: Journals, Physics

Entanglement and quantum combinatorial designs

10 hours 16 min ago

Author(s): Dardo Goyeneche, Zahra Raissi, Sara Di Martino, and Karol Życzkowski

We introduce several classes of quantum combinatorial designs, namely quantum Latin squares, cubes, hypercubes, and a notion of orthogonality between them. A further introduced notion, quantum orthogonal arrays, generalizes all previous classes of designs. We show that mutually orthogonal quantum La...


[Phys. Rev. A 97, 062326] Published Tue Jun 19, 2018

Categories: Journals, Physics

Quasiprobability representation of quantum coherence

10 hours 16 min ago

Author(s): J. Sperling and I. A. Walmsley

We introduce a general method for the construction of quasiprobability representations for arbitrary notions of quantum coherence. Our technique yields a non-negative probability distribution for the decomposition of any classical state. Conversely, quantum phenomena are certified in terms of signed...


[Phys. Rev. A 97, 062327] Published Tue Jun 19, 2018

Categories: Journals, Physics

Scale-invariant freezing of entanglement

Fri, 2018-06-15 12:00

Author(s): Titas Chanda, Tamoghna Das, Debasis Sadhukhan, Amit Kumar Pal, Aditi Sen(De), and Ujjwal Sen

We show that bipartite entanglement in an one-dimensional quantum spin model undergoing time evolution due to local Markovian environments can be frozen over time. We demonstrate this by using a number of paradigmatic quantum spin models including the anisotropic XY model in the presence of a unifor...


[Phys. Rev. A 97, 062324] Published Fri Jun 15, 2018

Categories: Journals, Physics

Asymptotic quantum algorithm for the Toeplitz systems

Fri, 2018-06-15 12:00

Author(s): Lin-Chun Wan, Chao-Hua Yu, Shi-Jie Pan, Fei Gao, Qiao-Yan Wen, and Su-Juan Qin

Solving the Toeplitz systems, which involves finding the vector x such that Tnx=b given an n×n Toeplitz matrix Tn and a vector b, has a variety of applications in mathematics and engineering. In this paper, we present a quantum algorithm for solving the linear equations of Toeplitz matrices, in whic...


[Phys. Rev. A 97, 062322] Published Fri Jun 15, 2018

Categories: Journals, Physics

Randomized benchmarking with restricted gate sets

Fri, 2018-06-15 12:00

Author(s): Winton G. Brown and Bryan Eastin

Standard randomized benchmarking protocols entail sampling from a unitary 2-design, which is not always practical. In this article we examine randomized benchmarking protocols based on subgroups of the Clifford group that are not unitary 2-designs. We introduce a general method for analyzing such pr...


[Phys. Rev. A 97, 062323] Published Fri Jun 15, 2018

Categories: Journals, Physics

Quantum arithmetics via computation with minimized external control: The half-adder

Wed, 2018-06-13 12:00

Author(s): Liam Eloie, Leonardo Banchi, and Sougato Bose

The while-you-wait computing paradigm combines elements of digital and analog quantum computation with the aim of minimizing the need of external control. In this architecture the computer is split into logic units, each continuously implementing a single recurring multigate operation via the unmodu...


[Phys. Rev. A 97, 062321] Published Wed Jun 13, 2018

Categories: Journals, Physics

Spatial search on a two-dimensional lattice with long-range interactions

Mon, 2018-06-11 12:00

Author(s): Tomo Osada, Kaoru Sanaka, William J. Munro, and Kae Nemoto

Quantum-walk-based algorithms that search a marked location among N locations on a d-dimensional lattice succeeds in time O(N) for d>2, while this is not found to be possible when d=2. In this paper, we consider a spatial search algorithm using continuous-time quantum walk on a two-dimensional sq...


[Phys. Rev. A 97, 062319] Published Mon Jun 11, 2018

Categories: Journals, Physics

Activation of zero-error classical capacity in low-dimensional quantum systems

Mon, 2018-06-11 12:00

Author(s): Jeonghoon Park and Jun Heo

Channel capacities of quantum channels can be nonadditive even if one of two quantum channels has no channel capacity. We call this phenomenon activation of the channel capacity. In this paper, we show that when we use a quantum channel on a qubit system, only a noiseless qubit channel can generate ...


[Phys. Rev. A 97, 062314] Published Mon Jun 11, 2018

Categories: Journals, Physics

ON states as resource units for universal quantum computation with photonic architectures

Mon, 2018-06-11 12:00

Author(s): Krishna Kumar Sabapathy and Christian Weedbrook

Universal quantum computation using photonic systems requires gates the Hamiltonians of which are of order greater than quadratic in the quadrature operators. We first review previous proposals to implement such gates, where specific non-Gaussian states are used as resources in conjunction with enta...


[Phys. Rev. A 97, 062315] Published Mon Jun 11, 2018

Categories: Journals, Physics

Fast and robust control of two interacting spins

Mon, 2018-06-11 12:00

Author(s): Xiao-Tong Yu, Qi Zhang, Yue Ban, and Xi Chen

Rapid preparation, manipulation, and correction of spin states with high fidelity are requisite for quantum information processing and quantum computing. In this paper, we propose a fast and robust approach for controlling two spins with Heisenberg and Ising interactions. By using the concept of sho...


[Phys. Rev. A 97, 062317] Published Mon Jun 11, 2018

Categories: Journals, Physics

Quantum memory and gates using a $\mathrm{Λ}$-type quantum emitter coupled to a chiral waveguide

Mon, 2018-06-11 12:00

Author(s): Tao Li, Adam Miranowicz, Xuedong Hu, Keyu Xia, and Franco Nori

By coupling a Λ-type quantum emitter to a chiral waveguide, in which the polarization of a photon is locked to its propagation direction, we propose a controllable photon-emitter interface for quantum networks. We show that this chiral system enables the swap gate and a hybrid-entangling gate betwee...


[Phys. Rev. A 97, 062318] Published Mon Jun 11, 2018

Categories: Journals, Physics

Numerical and analytical bounds on threshold error rates for hypergraph-product codes

Mon, 2018-06-11 12:00

Author(s): Alexey A. Kovalev, Sanjay Prabhakar, Ilya Dumer, and Leonid P. Pryadko

We study analytically and numerically decoding properties of finite-rate hypergraph-product quantum low density parity-check codes obtained from random (3,4)-regular Gallager codes, with a simple model of independent X and Z errors. Several nontrivial lower and upper bounds for the decodable region ...


[Phys. Rev. A 97, 062320] Published Mon Jun 11, 2018

Categories: Journals, Physics

Adiabatic leakage elimination operator in an experimental framework

Fri, 2018-06-08 12:00

Author(s): Zhao-Ming Wang, Mark S. Byrd, Jun Jing, and Lian-Ao Wu

Adiabatic evolution is used in a variety of quantum information processing tasks. However, the elimination of errors is not as well developed as it is for circuit model processing. Here, we present a strategy to improve the performance of a quantum adiabatic process by adding leakage elimination ope...


[Phys. Rev. A 97, 062312] Published Fri Jun 08, 2018

Categories: Journals, Physics

More nonlocality with less entanglement in Clauser-Horne-Shimony-Holt experiments using inefficient detectors

Fri, 2018-06-08 12:00

Author(s): Daniel Dilley and Eric Chitambar

It is well-known that in certain scenarios weakly entangled states can generate stronger nonlocal effects than their maximally entangled counterparts. In this paper, we consider violations of the Clauser-Horne-Shimony-Holt (CHSH) inequality when one party has inefficient detectors, a scenario known ...


[Phys. Rev. A 97, 062313] Published Fri Jun 08, 2018

Categories: Journals, Physics

Experimental witness of genuine high-dimensional entanglement

Thu, 2018-06-07 12:00

Author(s): Yu Guo, Xiao-Min Hu, Bi-Heng Liu, Yun-Feng Huang, Chuan-Feng Li, and Guang-Can Guo

Growing interest has been invested in exploring high-dimensional quantum systems, for their promising perspectives in certain quantum tasks. How to characterize a high-dimensional entanglement structure is one of the basic questions to take full advantage of it. However, it is not easy for us to cat...


[Phys. Rev. A 97, 062309] Published Thu Jun 07, 2018

Categories: Journals, Physics

Energy-constrained two-way assisted private and quantum capacities of quantum channels

Thu, 2018-06-07 12:00

Author(s): Noah Davis, Maksim E. Shirokov, and Mark M. Wilde

With the rapid growth of quantum technologies, knowing the fundamental characteristics of quantum systems and protocols is essential for their effective implementation. A particular communication setting that has received increased focus is related to quantum key distribution and distributed quantum...


[Phys. Rev. A 97, 062310] Published Thu Jun 07, 2018

Categories: Journals, Physics

Continuous-variable gate decomposition for the Bose-Hubbard model

Thu, 2018-06-07 12:00

Author(s): Timjan Kalajdzievski, Christian Weedbrook, and Patrick Rebentrost

In this work, we decompose the time evolution of the Bose-Hubbard model into a sequence of logic gates that can be implemented on a continuous-variable photonic quantum computer. We examine the structure of the circuit that represents this time evolution for one-dimensional and two-dimensional latti...


[Phys. Rev. A 97, 062311] Published Thu Jun 07, 2018

Categories: Journals, Physics

Trade-off relation for coherence and disturbance

Wed, 2018-06-06 12:00

Author(s): Gautam Sharma and Arun Kumar Pati

The measurement process necessarily disturbs the state of a quantum system, unless the state is an eigenstate of the observable being measured. Once we perform a complete measurement in a given basis, the system undergoes decoherence and loses its coherence. If there is no disturbance, the state ret...


[Phys. Rev. A 97, 062308] Published Wed Jun 06, 2018

Categories: Journals, Physics

Strong and uniform convergence in the teleportation simulation of bosonic Gaussian channels

Tue, 2018-06-05 12:00

Author(s): Mark M. Wilde

In the literature on the continuous-variable bosonic teleportation protocol due to Braunstein and Kimble [Phys. Rev. Lett. 80, 869 (1998)], it is often loosely stated that this protocol converges to a perfect teleportation of an input state in the limit of ideal squeezing and ideal detection, but th...


[Phys. Rev. A 97, 062305] Published Tue Jun 05, 2018

Categories: Journals, Physics