TY - JOUR
T1 - Dynamics, dephasing and clustering of impurity atoms in Bose-Einstein condensates
AU - Klein, Alexander
AU - Bruderer, Martin
AU - Clark, Stephen R.
AU - Jaksch, Dieter
PY - 2007/11/21
Y1 - 2007/11/21
N2 - 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.
AB - 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.
KW - quant-ph
UR - http://iopscience.iop.org/article/10.1088/1367-2630/9/11/411/pdf
UR - http://iopscience.iop.org/article/10.1088/1367-2630/9/11/411/meta
U2 - 10.1088/1367-2630/9/11/411
DO - 10.1088/1367-2630/9/11/411
M3 - Article
SN - 1367-2630
VL - 9
SP - 1
EP - 22
JO - New Journal of Physics
JF - New Journal of Physics
M1 - 202
ER -