Macroscopic Quantum Coherence Phenomena in Bose Einstein Condensates

Fernando Sols, Sigmund Kohler

Kendall B. Davis, M.‐O. Mewes, Michael R. Andrews +4 more

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

N. J. van Druten, Dallin Durfee, Kendall B. Davis +4 more

Summary form only given. Bose-Einstein condensation (BEG) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum statistical. The study of BEC in weakly interacting systems that can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Wolfgang Ketterle

A. Montina, F. T. Arecchi

We consider a Bose-Einstein condensate of ${}^{7}\mathrm{Li}$ in a situation where the density undergoes a symmetry breaking in real space. This occurs for a suitable number of condensed atoms in a double-well potential, obtained by adding a standing-wave light field to the trap potential. Evidence of bistability results from the solution of the Gross-Pitaevskii equation. By second quantization, we show that the classical bistable situation leads, in fact, to a macroscopic quantum superposition or Schr\"odinger cat (SC) and evaluate the tunneling rate between the two SC states. The oscillation between the two states is called macroscopic quantum coherence (MQC); we study the effects of losses on MQC.