Watching (de) Coherence in an Interacting Many Body System
Quantum coherence and Quantum noise is one of the most puzzling and fascinating aspects of quantum mechanics. Coherence can be observed in interference experiments.
In many-body systems it reveals the non-local correlations and entanglement of underlying many-body state. In experiments reported by Hofferberth et al in the 20th September issue of the journal Nature, the group at the Atominstitut Österreichischer Unversitäten presents experiments on AtomChips studying the interference of one dimensional systems, which reveal how the coherence slowly dies under the influence of an interacting many body system.
For two isolated 1d Bose gases the coherence factor exhibit a universal sub-exponential coherence decay in perfect agreement with Luttinger Liquid theory. For coupled 1d Bose gases the coherence factor is observed to approach a non-zero equilibrium value, the matter wave equivalent of phase locking two lasers by injection.
The non-equilibrium dynamics of super fluids studied by Hofferberth et al. plays an important role in a wide range of physical systems, such as superconductors, quantum-Hall systems, superfluid Helium, and spin systems. These experiments studying coherence dynamics show that 1d Bose gases are ideally suited for investigating this class of phenomena.
Literature:
Hofferberth et al.
Non-equilibrium coherence dynamics in one-dimensional Bose gases, Nature 449, 324 (2007).
News and Views: E. Altman, E. Demmler:
Relaxation after a tight squeeze, Nature 449, 296 (2007)
Folman, R., Krüger, P., Schmiedmayer, J., Denschlag, J. & Henkel, C.
Adv. At. Mol. Opt. Phys. 48, 263–356 (2002).
