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We introduce the Optimal Fingerprinting Process which is aimed at accurately
identifying the parameters which characterize the dynamics of a physical
system. A database is first built from the time evolution of an ensemble of
dynamical systems driven by a specific field, which is designed by optimal
control theory to maximize the efficiency of the recognition process. Curve
fitting is then applied to enhance the precision of the identification. As an
illustrative example, we consider the estimation of the relaxation parameters

A quantum state's entanglement across a bipartite cut can be quantified with
entanglement entropy or, more generally, Schmidt norms. Using only Schmidt
decompositions, we present a simple iterative algorithm to numerically find
pure states that maximize Schmidt norms, potentially minimizing or maximizing
entanglement across several bipartite cuts at the same time, possibly only
among states in a specified subspace.

We consider random number conversion (RNC) through random number storage with
restricted size. We clarify the relation between the performance of RNC and the
size of storage in the framework of first- and second- order asymptotics, and
derive their rate regions. Then, we show that the results for RNC with
restricted storage recover those for conventional RNC without storage in the
limit of storage size. To treat RNC via restricted storage, we introduce a new
kind of probability distributions named generalized Rayleigh-normal

The coherent tunnelling of Cooper pairs across Josephson junctions (JJs)
generates a nonlinear inductance that is used extensively in quantum
information processors based on superconducting circuits, from setting qubit
transition frequencies and interqubit coupling strengths, to the gain of
parametric amplifiers for quantum-limited readout. The inductance is either set
by tailoring the metal-oxide dimensions of single JJs, or magnetically tuned by
parallelizing multiple JJs in superconducting quantum interference devices

We introduce a notion of quantum function, and develop a compositional
framework for finite quantum set theory based on a 2-category of quantum sets
and quantum functions. We use this framework to formulate a 2-categorical
theory of quantum graphs, which captures the quantum graphs and quantum graph
homomorphisms recently discovered in the study of nonlocal games and zero-error
communication, and relates them to quantum automorphism groups of graphs
considered in the setting of compact quantum groups. We show that the

We show that any optimal unambiguous discrimination changes distinguishable
states indistinguishable when the inconclusive outcome is obtained, which was
proved under restricted conditions by Chefles [Phys. Lett. A 239, 339 (1998)].
Our proof is based on a simple observation which makes it easy and removes its
restrictions. The method may have a wide variety of applications in contexts
other than state discrimination.

We present an experimental study of nanowire transmons at zero and applied
in-plane magnetic field. With Josephson non-linearities provided by the
nanowires, our qubits operate at higher magnetic fields than standard
transmons. Nanowire transmons exhibit coherence up to 70 mT, where the induced
superconducting gap in the nanowire closes. We demonstrate that on-chip charge
noise coupling to the Josephson energy plays a dominant role in the qubit
dephasing. This takes the form of strongly-coupled two-level systems switching

We study quasi-two-dimensional dipolar Bose-Einstein condensates, in which
the Bogoliubov excitation spectrum displays, at sufficiently large gas density,
a deep roton minimum due to the spatially anisotropic behavior of the dipolar
two-body potential. A rapid quench, performed on the speed of sound of
excitations propagating on the condensate background, leads to the dynamical
Casimir effect, which can be characterized by measuring the density-density
correlation function. It is shown, for both zero and finite initial

Time-asymmetric spacetime structures, in particular those representing black
holes and the expansion of the universe, are intimately related to other arrows
of time, such as the second law and the retardation of radiation. The nature of
the quantum arrow, often attributed to a collapse of the wave function, is
essential, in particular, for understanding the much discussed "black hole
information loss paradox". However, this paradox assumes a new form and can

We report on the fabrication and characterization of a Fabry-Perot
microcavity enclosing a thin diamond membrane at cryogenic temperatures. The
cavity is designed to enhance resonant emission of single nitrogen-vacancy
centers by allowing spectral and spatial tuning while preserving the optical
properties observed in bulk diamond. We demonstrate cavity finesse at cryogenic
temperatures within the range of F = 4,000-12,000 and find a sub-nanometer
cavity stability. Modeling shows that coupling nitrogen-vacancy centers to