The real-time dynamics of systems with up to three SQUIDs is studied by
numerically solving the time-dependent Schr\"odinger equation. The numerical
results are used to scrutinize the mapping of the flux degrees of freedom onto
two-level systems (the qubits) as well as the performance of the intermediate
SQUID as a tunable coupling element. It is shown that the two-level
representation yields a good description of the flux dynamics during quantum
annealing, and the presence of the tunable coupling element does not have

We introduce a method for solving the Max-Cut problem using a variational
algorithm and a continuous-variables quantum computing approach. The quantum
circuit consists of two parts: the first one embeds a graph into a circuit
using the Takagi decomposition and the second is a variational circuit which
solves the Max-Cut problem. We analyze how the presence of different types of
non-Gaussian gates influences the optimization process by performing numerical

In this paper we present the detailed calculation of a new modular
Hamiltonian, namely that of a chiral fermion on a circle at non-zero
temperature. We provide explicit results for an arbitrary collection of
intervals, which we discuss at length by checking against known results in
different limits and by computing the associated modular flow. We also compute
the entanglement entropy, and we obtain a simple expression for it which
appears to be more manageable than those already existing in the literature.

Nanoscale quantum optics explores quantum phenomena in nanophotonics systems
for advancing fundamental knowledge in nano and quantum optics and for
harnessing the laws of quantum physics in the development of new
photonics-based technologies. Here, we review recent progress in the field with
emphasis on four main research areas: Generation, detection, manipulation and
storage of quantum states of light at the nanoscale, Nonlinearities and
ultrafast processes in nanostructured media, Nanoscale quantum coherence,

The advent of Noisy Intermediate-Scale Quantum (NISQ) technology is changing
rapidly the landscape and modality of research in quantum physics. NISQ
devices, such as the IBM Q Experience, have very recently proven their
capability as experimental platforms accessible to everyone around the globe.
Until now, IBM Q Experience processors have mostly been used for quantum
computation and simulation of closed systems. Here we show that these devices
are also able to implement a great variety of paradigmatic open quantum systems

The recent development of novel extreme ultraviolet (XUV) coherent light
sources bears great potential for a better understanding of the structure and
dynamics of matter. Promising routes are advanced coherent control and
nonlinear spectroscopy schemes in the XUV energy range, yielding unprecedented
spatial and temporal resolution. However, their implementation has been
hampered by the experimental challenge of generating XUV pulse sequences with
precisely controlled timing and phase properties. In particular, direct control

The difficulty of simulating quantum dynamics depends on the norm of the
Hamiltonian. When the Hamiltonian varies with time, the simulation complexity
should only depend on this quantity instantaneously. We develop quantum
simulation algorithms that exploit this intuition. For the case of sparse
Hamiltonian simulation, the gate complexity scales with the $L^1$ norm
$\int_{0}^{t}\mathrm{d}\tau\left\lVert H(\tau)\right\lVert_{\max}$, whereas the
best previous results scale with $t\max_{\tau\in[0,t]}\left\lVert

Quantum networking based on optical Gaussian states, although promising in
terms of scalability, is hindered by the fact that their entanglement cannot be
distilled via Gaussian operations. We show that optomechanics, integrable
(on-chip) availability, and particularly the scope to measure the mechanical
degree of freedom, can address this problem. Here, one of the optical modes of
a two-mode squeezed vacuum is injected into a single-sided Fabry-P\'{e}rot
cavity and non-linearly coupled to a mechanical oscillator. Afterward, the

We show that the cylindrical symmetry of the eigenvectors of the photon
position operator with commuting components, x, reflects the E(2) symmetry of
the photon little group. The eigenvectors of x form a basis of localized states
that have definite angular momentum, J, parallel to their common axis of
symmetry. This basis is well suited to the description of "twisted light" that
has been the subject of many recent experiments and calculations. Rotation of
the axis of symmetry of this basis results in the observed Berry phase

We study the entanglement generated in the steady state of two interacting
qubits coupled to thermal reservoirs. We show that the amount of steady-state
entanglement can be enhanced by the presence of a third thermal reservoir which
is common to both qubits. Specifically, we find that entanglement can be
enhanced as long as the temperature of the common reservoir is below the
thermalisation temperature of the qubits, whenever a single temperature can be
assigned to the steady state of the qubits in the absence of the common