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

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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