Fidelity Decay in Trapped Bose-Einstein Condensates

Giovanni Manfredi (1, 2) , Paul-Antoine Hervieux (1, 2)

1 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
2 CALVI - Scientific computation and visualization

The quantum coherence of a Bose-Einstein condensate is studied using the concept of quantum fidelity (Loschmidt echo). The condensate is confined in an elongated anharmonic trap and subjected to a small random potential such as that created by a laser speckle. Numerical experiments show that the quantum fidelity stays constant until a critical time, after which it drops abruptly over a single trap oscillation period. The critical time depends logarithmically on the number of condensed atoms and on the perturbation amplitude. This behavior may be observable by measuring the interference fringes of two condensates evolving in slightly different potentials.

Mots clés: Bose-Einstein condensate; quantum fidelity; Loschmidt echo; quantum coherence

Domaines: Physique Quantique [quant-ph]; Physique Atomique [physics.atom-ph]; Gaz Quantiques [cond-mat.quant-gas]

Giovanni Manfredi, Paul-Antoine Hervieux. Fidelity Decay in Trapped Bose-Einstein Condensates. Physical Review Letters, 2008, 100 (5), pp.050405. ⟨10.1103/PhysRevLett.100.050405⟩. ⟨hal-00596643⟩