Dynamics, dephasing and clustering of impurity atoms in Bose-Einstein condensates

Abstract

We investigate the influence of a Bose-Einstein condensate (BEC) on the properties of immersed impurity atoms, which are trapped in an optical lattice. Assuming a weak coupling of the impurity atoms to the BEC, we derive a quantum master equation for the lattice system. In the special case of fixed impurities with two internal states the atoms represent a quantum register and the quantum master equation reproduces the exact evolution of the qubits. We characterise the qubit dephasing which is caused by the interspecies coupling and show that the effect of sub- and superdecoherence is observable for realistic experimental parameters. Furthermore, the BEC phonons mediate an attractive interaction between the impurities, which has an important impact on their spatial distribution. If the lattice atoms are allowed to move, there occurs a sharp transition with the impurities aggregating in a macroscopic cluster at experimentally achievable temperatures. We also investigate the impact of the BEC on the transport properties of the impurity atoms and show that a crossover from coherent to diffusive behaviour occurs with increasing interaction strength.

22 pages, 8 figures, some typos corrected

References in corpus (5)

• Matrix Product Density Operators: Simulation of finite-T and dissipative systems
• Tuning the scattering length with an optically induced Feshbach resonance
• Non-Abelian gauge potentials for ultra-cold atoms with degenerate dark states
• Species-specific optical lattices
• Effective magnetic fields in degenerate atomic gases induced by light beams with orbital angular momenta

Cited by in corpus (2)

• Optical lattice quantum Hall effect
• Transport of strong-coupling polarons in optical lattices