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Author(s): Ivan M. Khaymovich, Masudul Haque, and Paul A. McClarty

The eigenstate thermalization hypothesis (ETH) is one of the cornerstones of contemporary quantum statistical mechanics. The extent to which ETH holds for nonlocal operators is an open question that we partially address in this Letter. We report on the construction of highly nonlocal operators, behe...

[Phys. Rev. Lett. 122, 070601] Published Tue Feb 19, 2019

Author(s): Xing-Yan Chen and Zhang-qi Yin

We propose a scheme to realize the controlled-phase gates between nitrogen-vacancy (NV) centers in an optically trapped nanodiamond, through a uniform magnetic field-induced coupling between the NV centers and the torsional mode of the levitated nanodiamond. The gates are insensitive to the thermal ...

[Phys. Rev. A 99, 022319] Published Tue Feb 19, 2019

Quantum channel simulations constructing probability tensors for biological multi-taxa in

phylogenetics are proposed. These are given in terms of positive trace preserving maps (quantum

channels), operating on quantum density matrices, using evolving systems of quantum walks with

multiple walkers. Simulation of a variety of standard phylogenetic branching models, applying on

trees of various topologies, is constructed using appropriate decoherent quantum circuits. For the

We use a tangent method approach to obtain the arctic curve in a model of non-intersecting lattice

paths within the first quadrant, including a q -dependent weight associated with the area delimited

by the paths. Our model is characterized by an arbitrary sequence of starting points along the

positive horizontal axis, whose distribution involves an arbitrary piecewise differentiable

function. We give an explicit expression for the arctic curve in terms of this arbitrary function

Discriminating between quantum states is a fundamental problem in quantum

information protocols. The optimum approach saturates the Helstrom bound, which

quantifies the unavoidable error probability of mistaking one state for

another. Computing the error probability directly requires complete knowledge

and diagonalization of the density matrices describing these states. Both of

these fundamental requirements become impractically difficult to obtain as the

dimension of the states grow large. In this article, we analyze quantum

In fundamental theories that accounts for quantum gravitational effects, the

spacetime causal structure is expected to be quantum uncertain. Previous

studies of quantum causal structure focused on finite-dimensional systems. Here

we present an algebraic framework that incorporates both finite- and

infinite-dimensional systems including quantum fields. Thanks to the absence of

a definite spacetime causal structure, Lagrangian quantum field theories can be

Schr\"odinger's famous Gedankenexperiment has inspired multiple generations

of physicists to think about apparent paradoxes that arise when the logic of

quantum physics is applied to macroscopic objects. The development of quantum

technologies enabled us to produce physical analogues of Schr\"odinger's cats,

such as superpositions of macroscopically distinct states as well as entangled

states of microscopic and macroscopic entities. Here we take one step further

In quantum physics the term `contextual' can be used in more than one way.

One usage, here called `Bell contextual' since the idea goes back to Bell, is

that if $A$, $B$ and $C$ are three quantum observables, with $A$ compatible

(i.e., commuting) with $B$ and also with $C$, whereas $B$ and $C$ are

incompatible, a measurement of $A$ might yield a different result (indicating

that quantum mechanics is contextual) depending upon whether $A$ is measured

along with $B$ (the $\{A,B\}$ context) or with $C$ (the $\{A,C\}$ context). An

In contrast with classical physics, in quantum physics some sets of

measurements are incompatible in the sense that they can not be performed

simultaneously. Among other applications, incompatibility allows for

contextuality and Bell nonlocality. This makes of crucial importance developing

tools for certifying whether a set of measurements posses a certain structure

of incompatibility. Here we show that, for quantum or nonsignaling models, if

the measurements employed in a Bell test satisfy a given type of compatibility,

A quantum vortex dipole, comprised of a closely bound pair of vortices of

equal strength with opposite circulation, is a spatially localized travelling

excitation of a planar superfluid that carries linear momentum, suggesting a

possible analogy with ray optics. We investigate numerically and analytically

the motion of a quantum vortex dipole incident upon a step-change in the

background superfluid density of an otherwise uniform two-dimensional

Bose-Einstein condensate. Due to the conservation of fluid momentum and energy,