# All

## Direct Randomized Benchmarking for Multiqubit Devices

Author(s): Timothy J. Proctor, Arnaud Carignan-Dugas, Kenneth Rudinger, Erik Nielsen, Robin Blume-Kohout, and Kevin Young
Benchmarking methods that can be adapted to multiqubit systems are essential for assessing the overall or “holistic” performance of nascent quantum processors. The current industry standard is Clifford randomized benchmarking (RB), which measures a single error rate that quantifies overall performan...
[Phys. Rev. Lett. 123, 030503] Published Fri Jul 19, 2019

## Modified belief propagation decoders for quantum low-density parity-check codes

Author(s): Alex Rigby, J. C. Olivier, and Peter Jarvis
Quantum low-density parity-check codes can be decoded using a syndrome based GF(4) belief propagation decoder (where GF denotes Galois field). However, the performance of this decoder is limited both by unavoidable 4-cycles in the code's factor graph and the degenerate nature of quantum errors. For ...
[Phys. Rev. A 100, 012330] Published Fri Jul 19, 2019

## Error reduction of quantum algorithms

Author(s): Debajyoti Bera and Tharrmashastha P. V.
We present a technique to reduce the error probability of quantum algorithms that determine whether its input has a specified property of interest. The standard process of reducing this error is statistical processing of the results of multiple independent executions of an algorithm. Denoting by $ρ$...
[Phys. Rev. A 100, 012331] Published Fri Jul 19, 2019

## Bath-Induced Decay of Stark Many-Body Localization

Author(s): Ling-Na Wu and André Eckardt
We investigate the relaxation dynamics of an interacting Stark-localized system coupled to a dephasing bath, and compare its behavior to the conventional disorder-induced many body localized system. Specifically, we study the dynamics of population imbalance between even and odd sites, and the growt...
[Phys. Rev. Lett. 123, 030602] Published Thu Jul 18, 2019

## Searching nonadiabatic holonomic quantum gates via an optimization algorithm

Author(s): Feihao Zhang, Jiang Zhang, Pan Gao, and Guilu Long
Nonadiabatic holonomic quantum computation (NHQC) offers a way to realize geometric quantum gates beyond the adiabatic regime. To extend the flexibility and control robustness, many NHQC schemes have been proposed. Here, we propose to use quantum optimal control theory to search control sequences th...
[Phys. Rev. A 100, 012329] Published Thu Jul 18, 2019

## Low cost quantum circuits for classically intractable instances of the Hamiltonian dynamics simulation problem. (arXiv:1805.04645v3 [quant-ph] UPDATED)

We develop circuit implementations for digital-level quantum Hamiltonian
dynamics simulation algorithms suitable for implementation on a reconfigurable
quantum computer, such as trapped ions. Our focus is on the co-design of a
problem, its solution, and quantum hardware capable of executing the solution
at the minimal cost expressed in terms of the quantum computing resources used
while demonstrating the solution of an instance of a scientifically interesting

## Optimal imaging of remote bodies using quantum detectors. (arXiv:1811.02192v3 [quant-ph] UPDATED)

We implement a general imaging method by measuring the complex degree of
coherence using linear optics and photon number resolving detectors. In the
absence of collective or entanglement assisted measurements, our method is
optimal over a large range of practically relevant values of the complex degree
of coherence. We measure the size and position of a small distant source of
pseudo-thermal light, and show that our method outperforms the traditional
imaging method by an order of magnitude in precision. Finally, we show that a

## Synchronization in PT-symmetric optomechanical resonators. (arXiv:1907.07415v1 [physics.optics])

Synchronization has great impacts in various fields such as self-clocking,
communication, neural networks, etc. Here we present a mechanism of
synchronization for two mechanical modes in two coupled optomechanical
resonators by introducing the so-called PT-symmetric structure. It is shown
that the degree of synchronization between the two far-off-resonant mechanical
modes can be increased by decreasing the coupling strength between the two
optomechanical resonators. Additionally, when we consider the stochastic noises

## Absence of topology in Gaussian mixed states of bosons. (arXiv:1901.04287v2 [quant-ph] UPDATED)

In a recent paper [Bardyn et al. Phys. Rev. X 8, 011035 (2018)], it was shown
that the generalization of the many-body polarization to mixed states can be
used to construct a topological invariant which is also applicable to
finite-temperature and non-equilibrium Gaussian states of lattice fermions. The
many-body polarization defines an ensemble geometric phase (EGP) which is
identical to the Zak phase of a fictitious Hamiltonian, whose symmetries
determine the topological classification. Here we show that in the case of

## Removing Staggered Fermionic Matter in $U(N)$ and $SU(N)$ Lattice Gauge Theories. (arXiv:1905.00652v2 [quant-ph] UPDATED)

Gauge theories, through the local symmetry which is in their core, exhibit
many local constraints, that must be taken care of and addressed in any
calculation. In the Hamiltonian picture this is phrased through the Gauss laws,
local constraints that restrict the physical Hilbert space and relate the
matter and gauge degrees of freedom. In this work, we present a way that uses
all the Gauss laws in lattice gauge theories with staggered fermions for
completely removing the matter degrees of freedom, at the cost of locally