arXiv subjects

I. Fuentes-Schuller

Publications and source records attributed to I. Fuentes-Schuller.

7 recordsLinked to original sources

arXiv2008

A perturbative approach to inelastic collisions in a Bose-Einstein Condensate

It has recently been discovered that for certain rates of mode-exchange collisions analytic solutions can be found for a Hamiltonian describing the two-mode Bose-Einstein condensate. We proceed to study the behavior of the system using perturbation theory if the coupling constants only approximately match these parameter constraints. We find that the model is robust to such perturbations. We study the effects of degeneracy on the perturbations and find that the induced changes differ greatly from the non-degenerate case. We also model inelastic collisions that result in particle loss or condensate decay as external perturbations and use this formalism to examine the effects of three-body recombination and background collisions.

quant-ph↗

arXiv2008

The black hole final state for the Dirac fields In Schwarzschild spacetime

We show that the internal stationary state of a black hole for massless Dirac fields can be represented by an entangled state of collapsing matter and infalling Hawking radiation. This implies that the Horowitz-Maldacena conjecture for the black hole final state originally proposed for the massless scalar fields is also applicable to fermionic fields as well. For an initially mixed state we find that the measure of mixedness is expected to decrease under evaporation.

hep-th↗

arXiv2007

Inelastic collisions in an exactly solvable two-mode Bose-Einstein Condensate

Inelastic collisions occur in Bose-Einstein condensates, in some cases, producing particle loss in the system. Nevertheless, these processes have not been studied in the case when particles do not escape the trap. We show that such inelastic processes are relevant in quantum properties of the system such as the evolution of the relative population, the self trapping effect and the probability distribution of particles. Moreover, including inelastic terms in the model of the two-mode condensate allows for an exact analytical solution. Using this solution, we show that collisions favor the generation of entanglement between the modes of the condensate as long as the collision rate does not exceed the natural frequency of the system.

quant-ph↗

arXiv2006

A family of many-body models which are exactly solvable analytically

We present a family of many-body models which are exactly solvable analytically. The models are an extended n-body interaction Lipkin-Meshkov-Glick model which considers spin-flip terms which are associated with the interaction of an external classical field which coherently manipulates the state of the system in order to, for example, process quantum information. The models also describe a two-mode Bose-Einstein condensate with a Josephson-type interaction which includes n-particle elastic and inelastic collisions. One of the models corresponds to the canonical two-mode Bose-Einstein Hamitonian plus a term which we argue must be considered in the description of the two-mode condensate. Intriguingly, this extra term allows for an exact and analytical solution of the two-particle collision two-mode BEC problem. Our results open up an arena to study many-body system properties analytically.

quant-ph↗

arXiv2006

Entanglement of Dirac fields in non-inertial frames

We analyze the entanglement between two modes of a free Dirac field as seen by two relatively accelerated parties. The entanglement is degraded by the Unruh effect and asymptotically reaches a non-vanishing minimum value in the infinite acceleration limit. This means that the state always remains entangled to a degree and can be used in quantum information tasks, such as teleportation, between parties in relative uniform acceleration. We analyze our results from the point of view afforded by the phenomenon of entanglement sharing and in terms of recent results in the area of multi-qubit complementarity.

quant-ph↗

arXiv2005

Alice falls into a black hole: Entanglement in non-inertial frames

Two observers determine the entanglement between two free bosonic modes by each detecting one of the modes and observing the correlations between their measurements. We show that a state which is maximally entangled in an inertial frame becomes less entangled if the observers are relatively accelerated. This phenomenon, which is a consequence of the Unruh effect, shows that entanglement is an observer-dependent quantity in non-inertial frames. In the high acceleration limit, our results can be applied to a non-accelerated observer falling into a black hole while the accelerated one barely escapes. If the observer escapes with infinite acceleration, the state's distillable entanglement vanishes.

quant-ph↗

arXiv2005

Entanglement in an expanding spacetime

We show that a dynamical spacetime generates entanglement between modes of a quantum field. Conversely, the entanglement encodes information concerning the underlying spacetime structure, which hints at the prospect of applications of this observation to cosmology. Here we illustrate this point by way of an analytically exactly soluble example, that of a scalar quantum field on a two-dimensional asymptotically flat Robertson-Walker expanding spacetime. We explicitly calculate the entanglement in the far future, for a quantum field residing in the vacuum state in the distant past. In this toy universe, it is possible to fully reconstruct the parameters of the cosmic history from the entanglement entropy.

quant-ph↗