12 research outputs found
Many-Body Effects in a Model of Electromagnetically Induced Transparency
We study the effect of inter-band interactions in the absorption profile of a
semi-classical model describing electromagnetically induced transparency. We
develop a consistent approach using a non-hermitian Hamiltonian to model
particle decay. This allow us to characterize the system response for different
number of particles so that the effect of particle-interaction on the
transmission profile can be studied over a wide range of characteristic
parameters.Comment: 5+ pages, 4 figure
End-to-end entanglement in Bose-Hubbard chains
We study the ground state as well as the dynamics of chains of bosons with
local repulsive interactions and nearest-neighbour exchange using numerical
techniques based on density matrix decimation. We explore the development of
entanglement between the terminal sites of such chains as mechanisms are
invoked to concentrate population in these sites. We find that long-range
entanglement in the ground state emerges as a result of hopping taking place at
the whole chain length in systems with appropriate hopping coefficients.
Additionally, we find appropriate perturbations to increase the entanglement
between the end sites above their ground state values.Comment: 7 pages, 8 figure
Thermalization of linear Fermi systems
The issue of thermalization in open quantum systems is explored from the
perspective of fermion models with quadratic couplings and linear baths. Both
the thermodynamic state and the stationary solution of the Lindblad equation
are rendered as a matrix-product sequence following a reformulation in terms of
underlying algebras, allowing to characterize a family of stationary solutions
and determine the cases where they correspond to thermal states. This
characterization provides insight into the operational mechanisms that lead the
system to thermalization and their interplay with mechanisms that tend to drive
it out of thermal equilibrium.Comment: 10 pages, 2 figures, Comments or suggestions are always welcom
Quantum Effects In Low Temperature Bosonic Systems
In the first part, we investigate the effect of long range particle exchange
in ideal bosonic chains. We establish that by using the Heisenberg formalism
along with matrix product state representation we can study the evolution as
well as the ground state of bosonic arrangements while including terms beyond
next-neighbour hopping. The method is then applied to analyse the quench
dynamics of condensates in a trapping potential and also to study the emergence
of entanglement as a result of collision in boson chains. In the second part,
we study the ground state as well as the dynamics of 1D boson arrangements with
local repulsive interactions and nearest-neighbour exchange using numerical
techniques based on time evolving block decimation (TEBD). We focus on the
development of quantum correlations between the terminal places of these
arrangements. We find that long-range entanglement in the ground state arises
as a result of intense boson tunnelling taking place across the whole chain in
systems with appropriate hopping coefficients. Additionally, we identify the
perturbations necessary to increase the entanglement between the end sites
above their ground state values. In the final part, we study the wave function
of a kicked condensate using a perturbative approach and compare the results
obtained in this way with numerical simulations.Comment: Ph.D. Thesi
Classical Dynamics of Quantum Entanglement
We numerically analyze the dynamical generation of quantum entanglement in a
system of 2 interacting particles, started in a coherent separable state, for
decreasing values of . As the entanglement entropy,
computed at any finite time, converges to a finite nonzero value. The limit law
that rules the time dependence of entropy is well reproduced by purely
classical computations. Its general features may then be explained by simple
classical arguments, which expose the different ways entanglement is generated
in systems which are classically chaotic or regular.Comment: 4 pages, 4 figures. New references to published related work have
been adde