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Exploring symmetry breaking at the Dicke quantum phase transition.
K Baumann1, R Mottl, F Brennecke
1Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland.
Physical Review Letters
|November 24, 2011
Summary
We observed symmetry breaking in Bose-Einstein condensates during a quantum phase transition in real time. This study explores how symmetry breaking depends on external fields and crossing rates, demonstrating coherent phase switching.
Area of Science:
- Quantum optics
- Condensed matter physics
- Atomic physics
Background:
- Bose-Einstein condensates exhibit quantum phase transitions.
- The Dicke quantum phase transition involves changes in system symmetry.
- Optical cavities can mediate interactions in quantum systems.
Purpose of the Study:
- To investigate symmetry breaking dynamics at the Dicke quantum phase transition.
- To observe and distinguish superradiant phases in real time.
- To analyze the influence of symmetry-breaking fields and critical crossing rates.
Main Methods:
- Coupling a Bose-Einstein condensate's motion to an optical cavity field.
- Utilizing optical heterodyne detection for real-time observation.
- Systematically varying symmetry-breaking fields and critical point crossing rates.
Main Results:
- Real-time observation of symmetry breaking.
- Distinction between the two superradiant phases.
- Demonstration of coherent switching between ordered phases.
- Dependence of symmetry breaking on external fields and crossing rates.
Conclusions:
- Symmetry breaking at the Dicke quantum phase transition can be observed in real time.
- The dynamics of symmetry breaking are sensitive to external perturbations.
- Coherent control over quantum phases is achievable in such systems.
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