M. Mehboudi | Searcharxiv

arXiv2018

Two distinguishable impurities in BEC: squeezing and entanglement of two Bose polarons

We study entanglement and squeezing of two uncoupled impurities immersed in a Bose-Einstein condensate. We treat them as two quantum Brownian particles interacting with a bath composed of the Bogoliubov modes of the condensate. The Langevin-like quantum stochastic equations derived exhibit memory effects. We study two scenarios: (i) In the absence of an external potential, we observe sudden death of entanglement; (ii) In the presence of an external harmonic potential, entanglement survives even at the asymptotic time limit. Our study considers experimentally tunable parameters.

cond-mat.quant-gas↗

arXiv2014

Quantum Metrology in Open Systems: Dissipative Cramér-Rao Bound

Estimation of parameters is a pivotal task throughout science and technology. Quantum Cramér-Rao bound provides a fundamental limit of precision allowed to achieve under quantum theory. For closed quantum systems, it has been shown how the estimation precision depends on the underlying dynamics. Here, we propose a general formulation for metrology scenarios in open quantum systems, aiming to relate the precision more directly to properties of the underlying dynamics. This feature may be employed to enhance an estimation precision, e.g., by quantum control techniques. Specifically, we derive a Cramér-Rao bound for a fairly large class of open system dynamics, which is governed by a (time-dependent) dynamical semi-group map. We illustrate the utility of this scenario through three examples.

quant-ph↗