Physics (Internal)

The Dissipative Dynamics of a Bose-Hubbard Dimer

This event is part of the Preliminary Oral Exam.

Examining Committee: David Campbell, Anatoli Polkovnikov, Richard Averitt, Emanual Katz

Abstract: The Bose-Hubbard dimer is a good model for certain systems of ultra cold gases in optical traps. One example is atoms in a double-well optical lattice; another is atoms in a single optical trap, but with two interacting spin states. For certain parameter values, the Bose-Hubbard dimer can be approximated by semiclassical equations of motion for z, the imbalance in the two modes' atomic populations, and φ, the modes' relative phase. Surprisingly, the semiclassical model not only predicts the dynamics of z and φ, but contains information about the entanglement of the modes: a coherent state centered near a fixed point of the semiclassical equations remains entangled much longer than one located near a separatrix.

If the classical phase space allows us to predict the robustness of an entangled state, could it suggest strategies for improving entanglement? One counterintuitive path to better entanglement is controlled dissipation. My work uses the semiclassical picture to shed light on the mechanisms by which dissipation in the form of atom loss affects entanglement in the Bose-Hubbard dimer. This allows me to distinguish purely quantum effects from semiclassical ones, and suggests novel approaches for realizing highly entangled states of spatially separated Bose-Einstein condensates.