3,879 research outputs found
Dissipation induced macroscopic entanglement in an open optical lattice
We introduce a method for the dissipative preparation of strongly correlated
quantum states of ultracold atoms in an optical lattice via localized particle
loss. The interplay of dissipation and interactions enables different types of
dynamics. This ushers a new line of experimental methods to maintain the
coherence of a Bose-Einstein condensate or to deterministically generate
macroscopically entangled quantum states.Comment: 4 figure
Non-hermitian approach to decaying ultracold bosonic systems
A paradigm model of modern atom optics is studied, strongly interacting
ultracold bosons in an optical lattice. This many-body system can be
artificially opened in a controlled manner by modern experimental techniques.
We present results based on a non-hermitian effective Hamiltonian whose quantum
spectrum is analyzed. The direct access to the spectrum of the metastable
many-body system allows us to easily identify relatively stable quantum states,
corresponding to previously predicted solitonic many-body structures
Mutual information and Bose-Einstein condensation
In the present work we are studying a bosonic quantum field system at finite
temperature, and at zero and non-zero chemical potential. For a simple spatial
partition we derive the corresponding mutual information, a quantity that
measures the total amount of information of one of the parts about the other.
In order to find it, we first derive the geometric entropy corresponding to the
specific partition and then we substract its extensive part which coincides
with the thermal entropy of the system. In the case of non-zero chemical
potential, we examine the influence of the underlying Bose-Einstein
condensation on the behavior of the mutual information, and we find that its
thermal derivative possesses a finite discontinuity at exactly the critical
temperature
Entropy production in Gaussian bosonic transformations using the replica method: application to quantum optics
In spite of their simple description in terms of rotations or symplectic
transformations in phase space, quadratic Hamiltonians such as those modeling
the most common Gaussian operations on bosonic modes remain poorly understood
in terms of entropy production. For instance, determining the von Neumann
entropy produced by a Bogoliubov transformation is notably a hard problem, with
generally no known analytical solution. Here, we overcome this difficulty by
using the replica method, a tool borrowed from statistical physics and quantum
field theory. We exhibit a first application of this method to the field of
quantum optics, where it enables accessing entropies in a two-mode squeezer or
optical parametric amplifier. As an illustration, we determine the entropy
generated by amplifying a binary superposition of the vacuum and an arbitrary
Fock state, which yields a surprisingly simple, yet unknown analytical
expression
Soliton Solutions with Real Poles in the Alekseev formulation of the Inverse-Scattering method
A new approach to the inverse-scattering technique of Alekseev is presented
which permits real-pole soliton solutions of the Ernst equations to be
considered. This is achieved by adopting distinct real poles in the scattering
matrix and its inverse. For the case in which the electromagnetic field
vanishes, some explicit solutions are given using a Minkowski seed metric. The
relation with the corresponding soliton solutions that can be constructed using
the Belinskii-Zakharov inverse-scattering technique is determined.Comment: 8 pages, LaTe
Analytical approximation of the exterior gravitational field of rotating neutron stars
It is known that B\"acklund transformations can be used to generate
stationary axisymmetric solutions of Einstein's vacuum field equations with any
number of constants. We will use this class of exact solutions to describe the
exterior vacuum region of numerically calculated neutron stars. Therefore we
study how an Ernst potential given on the rotation axis and containing an
arbitrary number of constants can be used to determine the metric everywhere.
Then we review two methods to determine those constants from a numerically
calculated solution. Finally, we compare the metric and physical properties of
our analytic solution with the numerical data and find excellent agreement even
for a small number of parameters.Comment: 9 pages, 10 figures, 3 table
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