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We provide sufficient conditions on the structure of the interaction
Hamiltonian between a quantum system and the surrounding bath which, without
any external drive or coherent measurements, guarantee the generation of
steady-state coherences (SSC). The SSC this way obtained remarkably turn out to
be independent on the initial state of the system, which therefore could even
be taken initially incoherent. We characterize in detail this phenomenon first
analytically in the weak coupling regime for two paradigmatic models, and then

We present uncertainty relations based on Wigner--Yanase--Dyson skew
information with quantum memory. Uncertainty inequalities both in product and
summation forms are derived. \mbox{It is} shown that the lower bounds contain
two terms: one characterizes the degree of compatibility of two measurements,
and the other is the quantum correlation between the measured system and the
quantum memory. Detailed examples are given for product, separable and
entangled states.

The possible connection between EPR correlations and superluminal
interactions is discussed using simple and palpable arguments. It is shown how
an experiment based on time-like events can allow us to answer the question
"Can a measurement performed on one of the photons of an entangled pair change
the state of the other?" The theorem on superluminal finite-speed causal
influences and superluminal signaling is reexamined. It is shown how
faster-than-light interactions and Lorentz transformations might peacefully
coexist.

Quantum mechanics allows measurements that surpass the fundamental
sensitivity limits of classical methods. To benefit from the quantum advantage
in a practical setting, the receiver should use communication channels
resources optimally; this can be done employing large communication alphabets.
Here we show the fundamental sensitivity potential of a quantum receiver for
coherent communication with frequency shift keying. We introduce an adaptive
quantum protocol for this receiver, show that its sensitivity outperforms other

Interference experiments provide a simple yet powerful tool to unravel
fundamental features of quantum physics. Here we engineer an RF-driven,
time-dependent bilinear coupling that can be tuned to implement a robust 50:50
beamsplitter between stationary states stored in two superconducting cavities
in a three-dimensional architecture. With this, we realize high contrast
Hong-Ou- Mandel (HOM) interference between two spectrally-detuned stationary
modes. We demonstrate that this coupling provides an efficient method for

We introduce the first complete and approximatively universal diagrammatic
language for quantum mechanics. We make the ZX-Calculus, a diagrammatic
language introduced by Coecke and Duncan, complete for the so-called Clifford+T
quantum mechanics by adding four new axioms to the language. The completeness
of the ZX-Calculus for Clifford+T quantum mechanics was one of the main open
questions in categorical quantum mechanics. We prove the completeness of the

We consider a general open system dynamics and we provide a recursive method
to derive the associated non-Markovian master equation in a perturbative
series. The approach relies on a momenta expansion of the open system
evolution. Unlike previous perturbative approaches of this kind, the method
presented in this paper provides a recursive definition of each perturbative
term. Furthermore, we give an intuitive diagrammatic description of each term
of the series, which pro- vides an useful analytical tool to build them and to

Recently, Rydberg atoms appeared as a viable alternative to the quantum gates
built on atomic or molecular ions. The lifetimes of the circular Rydberg states
can be in the millisecond range. That prevents inherent metastability of the
Rydberg atoms to influence computation at the typical decoherence times, which
are now being achieved in the range of 1 ms. The paper proposes to use a
pinning potential of an image charge on a cryogenic substrate (liquid He, in

There is recent interest in determining energy costs of shortcuts to
adiabaticity (STA), but different definitions of "cost" have been used. We
demonstrate the importance of taking into account the Control System (CS) for a
fair assessment of energy flows and consumptions. Models where the primary
system subjected to the shortcut and the CS can be examined explicitly help to
suggest, clarify, and test general principles, in particular the crucial
importance of the CS. We model the energy consumption and power to transport an

We show that for any collection of hermitian operators A1...An , and any
quantum state there is a unique joint distribution on R^n, with the property
that the marginals of all linear combinations of the operators coincide with
their quantum counterpart. We call it the Wigner distribution, because for
position and momentum this property defines the standard Wigner function. In
this note we discuss the application to finite dimensional systems, establish