# All

The Darmois-Skitovich theorem is a simple characterization of the normal

distribution in terms of the independence of linear forms. We present here a

non-commutative version of this theorem in the context of Gaussian bosonic

states and show that this theorem is stable under small errors in its

underlying conditions. An explicit estimate of the stability constants which

depend on the physical parameters of the problem is given.

We propose a reliable scheme to realize the ultrastrong Jaynes-Cummings (JC)

model by simultaneously modulating the resonance frequencies of the two-level

system and the bosonic mode in the ultrastrong quantum Rabi model. We find that

in both the high- and low-frequency modulation regimes, the counter-rotating

terms can be completely suppressed without reducing the coupling strength of

the rotating-wave terms, and hence the ultrastrong JC Hamiltonian is achieved.

We investigate unambiguous discrimination between given quantum states with a

sequential measurement, which is restricted to local measurements and one-way

classical communication. If the given states are binary or those each of whose

individual systems is two-dimensional, then it is in some cases known whether a

sequential measurement achieves a globally optimal unambiguous measurement. In

contrast, for more than two states each of whose individual systems is more

We investigate the mean-field phase diagram of the Bose-Hubbard model with

infinite-range interactions in two dimensions. This model describes ultracold

bosonic atoms confined by a two-dimensional optical lattice and dispersively

coupled to a cavity mode with the same wavelength as the lattice. We determine

the ground-state phase diagram for a grand-canonical ensemble by means of

analytical and numerical methods. Our results mostly agree with the ones

reported in Dogra et al. [PRA 94, 023632 (2016)], and have a remarkable

Recent studies using the quantum information theoretic approach to

thermodynamics show that the presence of coherence in quantum systems generates

corrections to classical fluctuation theorems. To explicate the physical

origins and implications of such corrections, we here convert an abstract

framework of an autonomous quantum Crooks relation into quantum Crooks

equalities for well-known coherent, squeezed and cat states. We further provide

a proposal for a concrete experimental scenario to test these equalities. Our

The braiding of two non-Abelian Majorana modes is important for realizing

topological quantum computation. It can be achieved through tuning the coupling

between the two Majorana modes to be exchanged and two ancillary Majorana

modes. However, this coupling also makes the braiding subject to

environment-induced decoherence. Here, we study the effects of decoherence on

the diabatic errors in the braiding process for a set of time-dependent

Hamiltonians with finite smoothness. To this end, we employ the master equation

The development of microwave photon detectors is paving the way for a wide

range of quantum technologies and fundamental discoveries involving single

photons. Here, we investigate the photon emission from a microwave cavity and

find that distribution of photon waiting times contains information about

few-photon processes, which cannot easily be extracted from standard

correlation measurements. The factorial cumulants of the photon counting

statistics are positive at all times, which may be intimately linked with the

We consider a spin $s$ subjected to both a static and an orthogonally applied

oscillating, circularly polarized magnetic field while being coupled to a heat

bath, and analytically determine the quasi\-stationary distribution of its

Floquet-state occupation probabilities for arbitrarily strong driving. This

distribution is shown to be Boltzmannian with a quasitemperature which is

different from the temperature of the bath, and independent of the spin quantum

number. We discover a remarkable formal analogy between the quasithermal

Mechanical systems facilitate the development of a new generation of hybrid

quantum technology comprising electrical, optical, atomic and acoustic degrees

of freedom. Entanglement is the essential resource that defines this new

paradigm of quantum enabled devices. Continuous variable (CV) entangled fields,

known as Einstein-Podolsky-Rosen (EPR) states, are spatially separated two-mode

squeezed states that can be used to implement quantum teleportation and quantum

The field of optomechanics provides us with several examples of quantum

photon-phonon interface. In this paper, we theoretically investigate the

generation and manipulation of quantum correlations in a microfabricated

optomechanical array. We consider a system consisting of localized photonic and

phononic modes interacting locally via radiation pressure at each lattice site

with the possibility of hopping of photons and phonons between neighboring

sites. We show that such an interaction can correlate various modes of a driven