The class of problems represented by frustrated cluster loops, FCL, is a
robust set of problems that spans a wide range of computational difficulty and
that are easy to determine what their solutions are. Here, we use frustrated
cluster loops to test the relative performance of the D-Wave without
post-processing and the D-Wave with multi-qubit correction (MQC)
post-processing. MQC post-processing has shown itself exceptionally beneficial
in improving the performance of the D-Wave 2000Q when processing difficult FCL

With quantum resources a precious commodity, their efficient use is highly
desirable. Quantum autoencoders have been proposed as a way to reduce quantum
memory requirements. Generally, an autoencoder is a device that uses machine
learning to compress inputs, that is, to represent the input data in a
lower-dimensional space. Here, we experimentally realize a quantum autoencoder,
which learns how to compress quantum data using a classical optimization
routine. We demonstrate that when the inherent structure of the data set allows

The effects caused by phonon-assisted tunnelling (PhAT) in a double quantum
dot (QD) molecule immersed in a cavity were studied under the quantum Markovian
master equation formalism in order to account for dissipation phenomena. We
explain how for higher PhAT rates, a stronger interaction between a QD and the
cavity at off-resonance takes place through the resonant interaction of another
QD and the cavity, where the QDs interact through tunnelling. A closer look at

We investigate the dynamics of the XXZ spin chain after a geometric quench,
which is realized by connecting two half-chains prepared in their ground states
with zero and maximum magnetizations, respectively. The profiles of
magnetization after the subsequent time evolution are studied numerically by
density-matrix renormalization group methods, and a comparison to the
predictions of generalized hydrodynamics yields a very good agreement. We also
calculate the profiles of entanglement entropy and propose an ansatz for the

Quantum key distribution (QKD) guarantees the secure communication between
legitimate parties with quantum mechanics. High-dimensional QKD (HDQKD) not
only increases the secret key rate but also tolerates higher quantum bit error
rate (QBER). Many HDQKD experiments have been realized by utilizing
orbital-angular-momentum (OAM) photons as the degree of freedom (DOF) of OAM of
the photon is a prospective resource for HD quantum information. In this work
we proposed and characterized that a high-quality HDQKD based on

Author(s): Akshata Shenoy H., Sébastien Designolle, Flavien Hirsch, Ralph Silva, Nicolas Gisin, and Nicolas Brunner
A sequential steering scenario is investigated, where multiple Bobs aim at demonstrating steering using successively the same half of an entangled quantum state. With isotropic entangled states of local dimension $d$, the number of Bobs that can steer Alice is found to be ${N}_{\mathrm{Bob}}∼d/logd$...
[Phys. Rev. A 99, 022317] Published Fri Feb 15, 2019

Author(s): Tao Wang, Peng Huang, Shiyu Wang, and Guihua Zeng
The simultaneous quantum and classical communication (SQCC) protocol is an appealing protocol since it allows continuous-variable quantum key distribution (CV-QKD) and classical communication to be implemented simultaneously by using the same communication infrastructure and on a single wavelength. ...
[Phys. Rev. A 99, 022318] Published Fri Feb 15, 2019

A variety of boundary value problems in linear transport theory are expressed as a diffusion
equation of the two-way, or forward–backward, type. In such problems boundary data are specified
only on part of the boundary, which introduces several technical challenges. Existence and
uniqueness theorems have been established in the literature under various assumptions; however,
calculating solutions in practice has proven difficult. Here we present one possible means of

In this paper the 3D Maxwell theory with single-sided planar boundary is studied. As a consequence
of the existence, on the boundary, of two Ward identities, we find two chiral conserved edge
currents satisfying a Kaç–Moody algebra with central charge equal to the inverse of the Maxwell
coupling constant. We show that the boundary degrees of freedom are two 2D scalar chiral bosons
whose chiralities depend on the parameters of the bulk Maxwell theory. In particular, the edge

Author(s): Yiğit Subaşı, Rolando D. Somma, and Davide Orsucci
We present two quantum algorithms based on evolution randomization, a simple variant of adiabatic quantum computing, to prepare a quantum state $|x⟩$ that is proportional to the solution of the system of linear equations $A\stackrel{→}{x}=\stackrel{→}{b}$. The time complexities of our algorithms are...
[Phys. Rev. Lett. 122, 060504] Published Thu Feb 14, 2019