Banaszek, W\'odkiewicz and others
(\cite{Banaszek},\cite{Chen},\cite{Chen-Zhang}) made the surprising discovery
that Einstein-Bell locality inequalities can be violated by the two mode
squeezed vacuum by a factor $\sqrt{2}$, in spite of the fact that the state has
a positive Wigner function. I use here the more general Gleason-Kochen-Specker
assumption of non-contextuality \cite{Gleason} to express classicality. I then
derive non-contextuality Bell inequalities for correlations of $N$ pseudo spins

We investigate the performance of error mitigation via measurement of
conserved symmetries on near-term devices. We present two protocols to measure
conserved symmetries during the bulk of an experiment, and develop a zero-cost
post-processing protocol which is equivalent to a variant of the quantum
subspace expansion. We develop methods for inserting global and local symetries
into quantum algorithms, and for adjusting natural symmetries of the problem to

We investigate the relation between a refined version of Leggett and Garg
conditions for macrorealism, namely the no-signaling-in-time (NSIT) conditions,
and the quantum mechanical notion of nondisturbance, and obtain a compatibility
relation among an arbitrary number of observables based on their minimally
disturbing sequential implementation. We show that all NSIT conditions are
satisfied for any state preparation if and only if simple compatibility
criteria on the state-update rules relative to the observables, i.e. quantum

Topological phases in spinless non-Hermitian models have been widely studied
both theoretically and experimentally in some artificial materials using
photonics and photonics. In this work, we investigate the interplay between
non-Hermitian loss and gain and non-Abelian gauge potential realized in a
two-component superconducting circuit. In our model, the non-Hermiticity along
only gives rise to trivial gain and loss to the states; while the non-Abelian
gauge along gives rise to flying butterfly spectra and associated edge modes,

Integrated photonics is an attractive platform for generating photonic
quantum states with high brightness, high stability and scalability. Many
schemes for generating photon pairs in an on-chip setting produce photons at
different frequencies and therefore the photons are distinguishable, which
limits their further use in many quantum information applications. Here, we use
the `dual-pump' technique and a silicon nanophotonic waveguide to produce
frequency-degenerate multi-photon quantum states. Two-photon and four-photon

We develop a general theoretical framework for measurement protocols
employing statistical correlations of randomized measurements. We focus on
locally randomized measurements implemented with local random unitaries in
quantum lattice models. In particular, we discuss the theoretical details
underlying the recent measurement of the second R\'{e}nyi entropy of highly
mixed quantum states consisting of up to $10$ qubits in a trapped-ion quantum

We systematically report a rigorous theory of the inverse scattering
transforms (ISTs) for the derivative nonlinear Schrodinger (DNLS) equation with
both zero boundary condition (ZBC)/non-zero boundary conditions (NZBCs) at
infinity and double poles of analytical scattering coefficients. The scattering
theories for both ZBC and NZBCs are addressed. The direct problem establishes
the analyticity, symmetries and asymptotic behavior of the Jost solutions and

Among certification techniques, those based on the violation of Bell
inequalities are appealing because they do not require assumptions on the
underlying Hilbert space dimension and on the accuracy of calibration methods.
Such device-independent techniques have been proposed to certify the quality of
entangled states, unitary operations, projective measurements following von
Neumann's model, and rank-one positive-operator-valued measures (POVM). Here,
we show that they can be extended to the characterization of generalized

We realize a potential platform for an efficient spin-photon interface namely
negatively-charged silicon-vacancy centers in a diamond membrane coupled to the
mode of a fully-tunable, fiber-based, optical resonator. We demonstrate that
introducing the thin ($\sim 200 \, \text{nm}$), single crystal diamond membrane
into the mode of the resonator does not change the cavity properties, which is
one of the crucial points for an efficient spin-photon interface. In

By means of studying the evolution equation for the Wigner distributions of
quantum dissipative systems we derive the quantum corrections to the classical
Liouville dynamics, taking into account the standard quantum friction model.
The resulting evolution turns out to be the classical one plus fluctuations
that depend not only on the $\hbar$ size but also on the momentum and the
dissipation parameter (i.e. the coupling with the environment). On the other
hand, we extend our studies of a paradigmatic system based on the kicked