In this paper, we propose a scheme of a long-lived broadband superefficient
multiresonator quantum memory in which a common resonator is connected with an
external waveguide and with a system of high-quality miniresonators containing
long-lived resonant electron spin ensembles. The scheme with 4 miniresonators
has been analyzed in details and it was shown that it is possible to store an
input broadband signal field to the electron spin ensembles with quantum

We present a blueprint for building a fault-tolerant universal quantum
computer with Rydberg atoms. Our scheme, which is based on the surface code,
uses individually-addressable optically-trapped atoms as qubits and exploits
electromagnetically induced transparency to perform the multi-qubit gates
required for error correction and computation. We discuss the advantages and
challenges of using Rydberg atoms to build such a quantum computer, and we
perform error correction simulations to obtain an error threshold for our

A common viewpoint is that a particle could be quantum entangled with another
particle arbitrarily far away. But in this paper we suggest that there is an
utmost distance for the existence of quantum entanglement between two
particles, beyond which the initial quantum entanglement would be broken by
some quantum gravitational effect. The utmost distance is proposed to be
$L_{QE}=\lambda^\alpha l_{p}^{1-\alpha}$, where $\lambda$ is the quantum
wavelength of the particles and $l_{p}= 1.616 \times 10^{-35} m$ is the Planck

We theoretically propose and investigate a feasible experimental scheme for
the realization of the dynamical Casimir effect (DCE) in a hybrid
optomechanical cavity with a moving end mirror containing an interacting
cigar-shaped Bose-Einstein condensate (BEC). We show that in the red-detuned
regime of cavity optomechanics together with the weak optomechanical coupling
limit by \textit{coherent} modulation of the \textit{s}-wave scattering
frequency of the BEC and the mechanical spring coefficient of the mechanical

The time evolution of periodically driven non-Hermitian systems is in general
non-unitary but can be stable. It is hence of considerable interest to examine
the adiabatic following dynamics in periodically driven non-Hermitian systems.
We show in this work the possibility of piecewise adiabatic following
interrupted by hopping between instantaneous system eigenstates. This
phenomenon is first observed in a computational model and then theoretically
explained, using an exactly solvable model, in terms of the Stokes phenomenon.

A communication game consists of distributed parties attempting to jointly
complete a task with restricted communication. Such games are useful tools for
studying limitations of physical theories. A theory exhibits preparation
contextuality whenever its predictions cannot be explained by a preparation
noncontextual model. Here, we show that communication games performed in
operational theories reveal the preparation contextuality of that theory. For
statistics obtained in a particular family of communication games, we show a

We compare two approaches to refine the "linear model" of cavity
optomechanics, in order to describe radiation pressure effects that are beyond
first order in the coupling constant. We compare corrections derived from (I) a
widely used phenomenological Hamiltonian that conserves the photon number and
(II) a two-mode truncation of C. K. Law's microscopic model, which we take as
the "true" Hamiltonian of the system. While these approaches agree at first
order, the latter model does not conserve the photon number, resulting in

In this work, we investigate the heat exchange between two quantum systems
whose initial equilibrium states are described by the generalized Gibbs
ensemble. First, we generalize the fluctuation relations for heat exchange
discovered by Jarzynski and W\'ojcik to quantum systems prepared in the
equilibrium states described by the generalized Gibbs ensemble at different
generalized temperatures. Second, we extend the connections between heat
exchange and R\'enyi divergences to quantum systems with very general initial

In a bipartite set-up, the vacuum state of a free Bosonic scalar field is
entangled in real space and satisfies the area-law--- entanglement entropy
scales linearly with area of the boundary between the two partitions. In this
work, we show that the area law is violated in two spatial dimensional model
Hamiltonian having dynamical critical exponent z=3. The model physically
corresponds to next-to-next-to-next nearest neighbour coupling terms on a
lattice. The result reported here is the first of its kind of violation of area

We generalize the recently proposed resource theory of coherence (or
superposition) [Baumgratz, Cramer & Plenio, Phys. Rev. Lett. 113:140401; Winter
& Yang, Phys. Rev. Lett. 116:120404] to the setting where not only the free
("incoherent") resources, but also the objects manipulated are quantum
operations, rather than states. In particular, we discuss an information
theoretic notion of coherence capacity of a quantum channel, and prove a
single-letter formula for it in the case of unitaries. Then we move to the