Decoherence of trapped bosons by buffer gas scattering: What length scales matter?
arXiv:1402.3075 · doi:10.1103/PhysRevA.89.052131
Abstract
We ask and answer a basic question about the length scales involved in quantum decoherence: how far apart in space do two parts of a quantum system have to be, before a common quantum environment decoheres them as if they were entirely separate? We frame this question specifically in a cold atom context. How far apart do two populations of bosons have to be, before an environment of thermal atoms of a different species (`buffer gas') responds to their two particle numbers separately? An initial guess for this length scale is the thermal coherence length of the buffer gas; we show that a standard Born-Markov treatment partially supports this guess, but predicts only inverse-square saturation of decoherence rates with distance, and not the much more abrupt Gaussian behavior of the buffer gas's first-order coherence. We confirm this Born-Markov result with a more rigorous theory, based on an exact solution of a two-scatterer scattering problem, which also extends the result beyond weak scattering. Finally, however, we show that when interactions within the buffer gas reservoir are taken into account, an abrupt saturation of the decoherence rate does occur, exponentially on the length scale of the buffer gas's mean free path.
References in corpus (14)
- Decoherence, einselection, and the quantum origins of the classical
- Decoherence Free Subspaces for Quantum Computation
- Decoherence of quantum registers
- Quantum Kinetic Theory I: A Quantum Kinetic Master Equation for Condensation of a weakly interacting Bose gas without a trapping potential
- Universality of Decoherence
- Bose-Einstein condensate in a double-well potential as an open quantum system
- Quantifying, characterizing and controlling information flow in ultracold atomic gases
- Quantum Kinetic Theory III: Quantum kinetic master equation for strongly condensed trapped systems
- Cold, dilute, trapped bosons as an open quantum system
- Collective decoherence of cold atoms coupled to a Bose-Einstein condensate
- Decoherence of Bose-Einstein condensates in traps at finite temperature
- Inserting single Cs atoms into an ultracold Rb gas
- Quantum Kinetic Theory of Collisionless Superfluid Internal Convection
- Number-conserving master equation theory for a dilute Bose-Einstein condensate