We consider an unexplored aspect of the mass equivalence principle in the
quantum realm, its connection with atomic stability. We show that if the
gravitational mass were different from the inertial one, a Hydrogen atom placed
in a constant gravitational field would become unstable in the long term. In
contrast, independently of the relation between the two masses, the atom does
not become ionized in an uniformly accelerated frame. This work, in the line of

Inspired by the decomposition in the hybrid quantum-classical optimization
algorithm we introduced in arXiv:1902.04215, we propose here a new (fully
classical) approach to solving certain non-convex integer programs using Graver
bases. This method is well suited when (a) the constraint matrix $A$ has a
special structure so that its Graver basis can be computed systematically, (b)
several feasible solutions can also be constructed easily and (c) the objective

We study the steady state entanglement and correlations of an open system
comprised of two fermions coupling with the equilibrium or nonequilibrium
environments. We find that for equilibrium case, quantum correlations exhibit
non-monotonic behavior with the increase of temperature and quantum
entanglement dies at finite temperature. Under nonequilibrium environments, the
quantum correlations can show monotonic or non-monotonic behavior upon the
change of temperature or chemical potential bias depending on the tunneling

Great advances in precision quantum measurement have been achieved with
trapped ions and atomic gases at the lowest possible temperatures. These
successes have inspired ideas to merge the two systems. In this way one can
study the unique properties of ionic impurities inside a quantum fluid or
explore buffer gas cooling of the trapped ion quantum computer. Remarkably, in
spite of its importance, experiments with atom-ion mixtures remained firmly
confined to the classical collision regime. We report a collision energy of

The study of quantum dynamics featuring memory effects has always been a
topic of interest within the theory of open quantum system, which is concerned
about providing useful conceptual and theoretical tools for the description of
the reduced dynamics of a system interacting with an external environment.
Definitions of non-Markovian processes have been introduced trying to capture
the notion of memory effect by studying features of the quantum dynamical map
providing the evolution of the system states, or changes in the

We consider a continuous-time quantum walk on a triple graph and investigate
the influence of the side chain on the propagation in the main chain.
Calculating the interchange of the probabilities between the two parts of the
main chain, we find that a switching effect appears if there are odd number of
points on the side chain when concrete conditions between the length of the
main chain and the position of the side chain are satisfied. Whereas, such an

The realization of the strong coupling regime is requisite for implementing
quantum information tasks. Here, a method for enhancing the atom-field coupling
in highly dissipative coupled cavities is proposed. By introducing parametric
squeezing into the primary cavity which is only virtually excited under
specific parametric conditions, coupling enhancement between atom and auxiliary
cavity is realized for proper squeezing parameters. This enables the system to

Consider a classical system, which is in the state described by probability
distribution $p$ or $q$, and embed these classical informations into quantum
system by a physical map $\Gamma$, $\rho=\Gamma(p)$ and $\sigma=\Gamma(q)$.
Intuitively, the pair $\{p_{\rho}^{M},p_{\sigma}^{M}\}$ of the distributions of
the data of the measurement $M$ on the pair $\{\rho,\sigma\}$ should contain
strictly less information than the pair $\{p,q\}$ provided the pair
$\{\rho,\sigma\}$ is non-commutative. Indeed, this statement had been shown if