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Author(s): Anna Goremykina, Romain Vasseur, and Maksym Serbyn
We introduce a simple, exactly solvable strong-randomness renormalization group (RG) model for the many-body localization (MBL) transition in one dimension. Our approach relies on a family of RG flows parametrized by the asymmetry between thermal and localized phases. We identify the physical MBL tr...
[Phys. Rev. Lett. 122, 040601] Published Mon Jan 28, 2019

We propose an efficient single-photon router comprising two resonator
waveguide channels coupled by several sequential cavities with embedded
three-level atoms. We show that the system can operate as a perfect four-way
single-photon switch. We also demonstrate that an incident single-photon
propagating in one of the waveguides can be routed into one or the other output
channels; such routing can be controlled by the external classical
electromagnetic field driving the atoms. We argue that, under appropriate

We present exact numerical calculations of supercurrent density, inductance,
and impurity-induced flux noise of cylindrical superconducting wires in the
nonlocal Pippard regime, which occurs when the Pippard coherence length is
larger than the London penetration depth. In this regime the supercurrent
density displays a peak away from the surface, and changes sign inside the
superconductor, signalling a breakdown of the usual approximation of local
London electrodynamics with a renormalized penetration depth. Our calculations

Memory effects play an important role in the theory of open quantum systems.
There are two completely independent insights about memory for quantum
channels. In quantum information theory, the memory of the quantum channel is
depicted by the correlations between consecutive uses of the channel on a set
of quantum systems. In the theory of open quantum systems memory effects result
from correlations which are created during the quantum evolution. Here, we
study the behavior of the actual speed of the quantum evolution under the

Vacuum fluctuations fundamentally affect an atom by inducing a finite excited
state lifetime along with a Lamb shift of its transition frequency. Here we
report the reverse effect: modification of vacuum modes by a single atom in
circuit quantum electrodynamics. Our one-dimensional vacuum is a long section
of a high wave impedance (comparable to resistance quantum) superconducting
transmission line. It is directly wired to a transmon qubit circuit. Owing to

The coherent Ising machine (CIM) enables efficient sampling of low-lying
energy states of the Ising Hamiltonian with all-to-all connectivity by encoding
the spins in the amplitudes of pulsed modes in an optical parametric oscillator
(OPO). The interaction between the pulses is realized by means of
measurement-based optoelectronic feedforward which enhances the gain for
lower-energy spin configurations. We present an efficient method of simulating
the CIM on a classical computer that outperforms the CIM itself as well as the

Non-Hermitian (NH) Hamiltonians have become an important asset for the
effective description of various physical systems that are subject to
dissipation. Motivated by recent experimental progress on realizing the NH
counterparts of gapless phases such as Weyl semimetals, here we investigate how
NH symmetries affect the occurrence of exceptional points (EPs), that
generalize the notion of nodal points in the spectrum beyond the Hermitian
realm. Remarkably, we find that the dimension of the manifold of EPs is

The Hopf insulator represents a topological state of matter that exists
outside the conventional ten-fold way classification of topological insulators.
Its topology is protected by a linking number invariant, which arises from the
unique topology of knots in three dimensions. We predict that three-dimensional
arrays of driven, dipolar-interacting spins are a natural platform to
experimentally realize the Hopf insulator. In particular, we demonstrate that

It is now widely recognized that the Shannon measure of information is a
fundamental tool that can be employed across many fields. The quantum
mechanical notion of entropy created by von Neumann is a measure of the purity
of a quantum state described by a density matrix. Jaynes applied information
theoretic entropy to both statistical mechanics and quantum theory using the
principle of maximum entropy. We apply the Shannon measure, as developed by
Ben-Naim, to the general problem of characterizing the information about a

We present a method for preparing a single two-dimensional sample of a
two-spin mixture of fermionic potassium in a single antinode of an optical
lattice, in a quantum-gas microscope apparatus. Our technique relies on
spatially-selective microwave transitions in a magnetic field gradient.
Adiabatic transfer pulses were optimized for high efficiency and minimal atom
loss and heating due to spin-changing collisions. We have measured the dynamics
of those loss processes, which are more pronounced in the presence of a spin