All

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

We investigate the patterns in distributions of localizable entanglement over
a pair of qubits for random multi-qubit pure states. We observe that the mean
of localizable entanglement increases gradually with increasing the number of
qubits of random pure states while the standard deviation of the distribution
decreases. The effects on the distributions, when the random pure multi-qubit
states are subjected to local as well as global noisy channels, are also
investigated. Unlike the noiseless scenario, the average value of the

We investigate the computational hardness of spin-glass instances on a square
lattice, generated via a recently introduced tunable and scalable approach for
planting solutions. The method relies on partitioning the problem graph into
edge-disjoint subgraphs, and planting frustrated, elementary subproblems that
share a common local ground state, which guarantees that the ground state of
the entire problem is known a priori. Using population annealing Monte Carlo,

We report on a highly controllable, hybrid quantum system consisting of cold
Rydberg atoms and an optical nanofiber interface. Using a two-photon excitation
process to drive $5S \rightarrow 5P \rightarrow 29D $ transitions in $^{87}$Rb,
we observe both coherent and incoherent excitation of the Rydberg atoms at
submicron distances from the fiber surface. The $5S \rightarrow 5D$ transition
is mediated by the cooling laser at 780 nm, while the $5D \rightarrow 29D$

Helium nanodroplets doped with polar molecules are studied by electrostatic
deflection. This broadly applicable method allows even polyatomic molecules to
attain sub-Kelvin temperatures and nearly full orientation in the field. The
resulting intense force from the field gradient strongly deflects even droplets
with tens of thousands of atoms, the most massive neutral systems studied by
beam "deflectometry." We use the deflections to extract droplet size
distributions. Moreover, since each host droplet deflects according to its

Out-of-time-ordered correlators (OTOCs) have been proposed as a tool to
witness quantum information scrambling in many-body system dynamics. These
correlators can be understood as averages over nonclassical multi-time
quasi-probability distributions (QPDs). These QPDs have more information, and
their nonclassical features witness quantum information scrambling in a more
nuanced way. However, their high dimensionality and nonclassicality make QPDs
challenging to measure experimentally. We focus on the topical case of a

Pages