PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 20 min 37 sec ago

Continuous quantum clock with high precision and long recurrence time

Tue, 2022-08-23 11:00

Author(s): Mehdi Ramezani, Morteza Nikaeen, and Alireza Bahrampour

Continuous clocks, i.e., clocks that measure time in a continuous manner, are regarded as an essential component of sensing technology. Precision and recurrence time are two basic features of continuous clocks. In this paper, in the framework of quantum estimation theory various models for continuou…


[Phys. Rev. A 106, 022427] Published Tue Aug 23, 2022

Categories: Journals, Physics

Creating quantum correlations in generalized entanglement swapping

Tue, 2022-08-23 11:00

Author(s): Pratapaditya Bej, Arkaprabha Ghosal, Arup Roy, Shiladitya Mal, and Debarshi Das

We study how different types of quantum correlations can be established as the consequence of a generalized entanglement swapping protocol where, starting from two Bell pairs (1,2) and (3,4), a general quantum measurement [denoted by a positive operator-valued measure (POVM)] is performed on the pai…


[Phys. Rev. A 106, 022428] Published Tue Aug 23, 2022

Categories: Journals, Physics

Quantum Cramér-Rao bound for quantum statistical models with parameter-dependent rank

Tue, 2022-08-23 11:00

Author(s): Yating Ye and Xiao-Ming Lu

Recently a widely used computation expression for quantum Fisher information was shown to be discontinuous at the parameter points where the rank of the parametric density operator changes. The quantum Cramér-Rao bound can be violated on such singular parameter points if one uses this computation ex…


[Phys. Rev. A 106, 022429] Published Tue Aug 23, 2022

Categories: Journals, Physics

Qubit control noise spectroscopy with optimal suppression of dephasing

Tue, 2022-08-23 11:00

Author(s): Robert Barr, Yasuo Oda, Gregory Quiroz, B. David Clader, and Leigh M. Norris

We extend quantum noise spectroscopy (QNS) of amplitude control noise to settings where dephasing noise or detuning errors make significant contributions to qubit dynamics. Previous approaches to characterize amplitude noise are limited by their vulnerability to low-frequency dephasing noise and sta…


[Phys. Rev. A 106, 022425] Published Tue Aug 23, 2022

Categories: Journals, Physics

Optimal two-qubit gates in recurrence protocols of entanglement purification

Mon, 2022-08-22 11:00

Author(s): Francesco Preti, Tommaso Calarco, Juan Mauricio Torres, and József Zsolt Bernád

We propose and investigate a method to optimize recurrence entanglement purification protocols. The approach is based on a numerical search in the whole set of SU(4) matrices with the aid of a quasi-Newton algorithm. Our method evaluates average concurrences where the probabilistic occurrence of mix…


[Phys. Rev. A 106, 022422] Published Mon Aug 22, 2022

Categories: Journals, Physics

Long-range entanglement in quantum dots with Fermi-Hubbard physics

Mon, 2022-08-22 11:00

Author(s): Sanaa Abaach, Mustapha Faqir, and Morad El Baz

The range of entanglement in quantum dots, under the effect of the Coulomb interaction and the system's size, is investigated. As ququart systems, naturally described by the Fermi-Hubbard model, we show that quantum dots supply long-range entanglement up to the third neighbor. In conjunction with th…


[Phys. Rev. A 106, 022421] Published Mon Aug 22, 2022

Categories: Journals, Physics

Entanglement perspective on the quantum approximate optimization algorithm

Mon, 2022-08-22 11:00

Author(s): Maxime Dupont, Nicolas Didier, Mark J. Hodson, Joel E. Moore, and Matthew J. Reagor

Many quantum algorithms seek to output a specific bitstring solving the problem of interest—or a few if the solution is degenerate. It is the case for the quantum approximate optimization algorithm (QAOA) in the limit of large circuit depth, which aims to solve quadratic unconstrained binary optimiz…


[Phys. Rev. A 106, 022423] Published Mon Aug 22, 2022

Categories: Journals, Physics

Simulating open quantum dynamics on an NMR quantum processor using the Sz.-Nagy dilation algorithm

Mon, 2022-08-22 11:00

Author(s): Akshay Gaikwad, Arvind, and Kavita Dorai

We experimentally implement the Sz.-Nagy dilation algorithm to simulate open quantum dynamics on a nuclear magnetic resonance quantum processor. The Sz.-Nagy algorithm enables the simulation of the dynamics of an n-qubit system using n+1 qubits. We experimentally simulate the action of three nonunit…


[Phys. Rev. A 106, 022424] Published Mon Aug 22, 2022

Categories: Journals, Physics

Spatial search via an interpolated memoryless walk

Fri, 2022-08-19 11:00

Author(s): Peter Høyer and Janet Leahy

The defining feature of memoryless quantum walks is that they operate on the vertex space of a graph and therefore can be used to produce search algorithms with minimal memory. We present a memoryless walk that can find a unique marked vertex on a two-dimensional lattice. Our walk is based on the co…


[Phys. Rev. A 106, 022418] Published Fri Aug 19, 2022

Categories: Journals, Physics

Sign switching of superexchange mediated by a few electrons in a nonuniform magnetic field

Fri, 2022-08-19 11:00

Author(s): Guo Xuan Chan and Xin Wang

Long-range interaction between distant spins is an important building block for the realization of a large quantum-dot network in which couplings between pairs of spins can be selectively addressed. Recent experiments on the coherent oscillation of logical states between remote spins facilitated by …


[Phys. Rev. A 106, 022420] Published Fri Aug 19, 2022

Categories: Journals, Physics

Fast and robust quantum state transfer assisted by zero-energy interface states in a splicing Su-Schrieffer-Heeger chain

Fri, 2022-08-19 11:00

Author(s): Lijun Huang, Zhi Tan, Honghua Zhong, and Bo Zhu

We propose a fast, robust, and long-distance quantum state transfer (QST) protocol via a splicing Su-Schrieffer-Heeger (SSH) chain, where the interchain couplings vary with the change in the phase parameter and the single or splicing SSH chain can be designed by adjusting it. It is found that the ex…


[Phys. Rev. A 106, 022419] Published Fri Aug 19, 2022

Categories: Journals, Physics

Control of population and entanglement of two qubits under the action of different types of dissipative noise

Fri, 2022-08-19 11:00

Author(s): G. J. Delben, A. L. O. dos Santos, and M. G. E. da Luz

We investigate the quantum control of two qubits interacting with a Markovian environment and evolving as an X state. The control is implemented via a simple applied field, whose profile is determined by means of the piecewise time-independent quantum control method. The goal is to make either the p…


[Phys. Rev. A 106, 022417] Published Fri Aug 19, 2022

Categories: Journals, Physics