Arrays of coupled semiconductor lasers are systems possessing complex
dynamical behavior that are of major interest in photonics and laser science.
The onset of dynamical instabilities arising from supermode competition and
slow carrier dynamics is known to prevent stable phase locking in a wide range
of parameter space, requiring special methods to realize stable laser
operation. Inspired by recent concepts of parity-time ($\mathcal{PT}$) and
non-Hermitian photonics, in this work we consider non-Hermitian coupling

In [arXiv:1712.03219] the existence of a strongly (pointwise) converging
sequence of quantum channels that can not be represented as a reduction of a
sequence of unitary channels strongly converging to a unitary channel is shown.
In this work we give a simple characterization of sequences of quantum channels
that have the above representation. The corresponding convergence is called the
$*$-strong convergence, since it relates to the convergence of selective

Bragg waveguides are promising optical filters for pump suppression in
spontaneous Four-Wave Mixing (FWM) photon sources. In this work, we investigate
the generation of unwanted photon pairs in the filter itself. We do this by
taking advantage of the relation between spontaneous and classical FWM, which
allows for the precise characterisation of the nonlinear response of the
device. The pair generation rate estimated from the classical measurement is
compared with the theoretical value calculated by means of a full quantum model

In this paper, we introduce quantum fidelity based measurement induced
nonlocality for the bipartite state over two-sided von Neumann projective
measurements. While all the properties of this quantity are reflected from that
of one-sided measurement, the latter one is shown to set an upper bound for
arbitrary bipartite state. As an illustration, we have studied the nonlocality
of Bell diagonal state.

We analytically investigate the recently proposed and implemented
discrete-time quantum walk based on kicked ultra-cold atoms. We show how the
internal level structure of the kicked atoms leads to the emergence of a
relative light-shift phase immediately relevant for the experimental
realization. Analytical solutions are provided for the momentum distribution
for both the case of quantum resonance and the near-resonant quasimomenta.

The core problem in optimal control theory applied to quantum systems is to
determine the temporal shape of an applied field in order to maximize the
expectation of value of some physical observable. The functional which maps the
control field into a given value of the observable defines a Quantum Control
Landscape (QCL). Studying the topological and structural features of these
landscapes is of critical importance for understanding the process of finding

This book is an introduction to quantum Markov chains and explains how this
concept is connected to the question of how well a lost quantum mechanical
system can be recovered from a correlated subsystem. To achieve this goal, we
strengthen the data-processing inequality such that it reveals a statement
about the reconstruction of lost information. The main difficulty in order to
understand the behavior of quantum Markov chains arises from the fact that

The 1-D Anderson model possesses a completely localized spectrum of
eigenstates for all values of the disorder. We consider the effect of
projecting the Hamiltonian to a truncated Hilbert space, destroying time
reversal symmetry. We analyze the ensuing eigenstates using different measures
such as inverse participation ratio and sample-averaged moments of the position
operator. In addition, we examine amplitude fluctuations in detail to detect
the possibility of multifractal behavior (characteristic of mobility edges)

Non-Markovian quantum effects are typically observed in systems interacting
with structured reservoirs. Discrete-time quantum walks are prime example of
such systems in which, quantum memory arises due to the controlled interaction
between the coin and position degrees of freedom. Here we show that the
information backflow that quantifies memory effects can be enhanced when the
particle is subjected to uncorrelated static or dynamic disorder. The presence
of disorder in the system leads to localization effects in 1-dimensional

We study a one-dimensional system of strongly-correlated bosons interacting
with a dynamical lattice. A minimal model describing the latter is provided by
extending the standard Bose-Hubbard Hamiltonian to include extra degrees of
freedom on the bonds of the lattice. We show that this model is capable of
reproducing phenomena similar to those present in usual fermion-phonon models.
In particular, we discover a bosonic analog of the Peierls transition, where