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Published on: August 2, 2019
Quantum fluctuations in the time-dependent BCS-BEC crossover
1Fachbereich Physik, Technische Universität Kaiserslautern, Kaiserslautern, Germany.
Summary
Researchers explored the formation of molecular Bose-Einstein condensates from fermionic atoms using a novel path integral approach. This study offers insights into quantum phase transitions and condensate dynamics, drawing parallels with cosmological phenomena.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Quantum Gases
- Condensed Matter Theory
Background:
- Bose-Einstein condensates (BECs) are crucial states of matter with applications in quantum computing and precision measurement.
- Understanding the dynamics of condensate formation from fermionic atoms is key to controlling quantum states.
- Feshbach resonances provide a powerful tool to tune the interactions between atoms, enabling the creation of molecules and control over BECs.
Purpose of the Study:
- To theoretically describe the time-dependent formation of a molecular Bose-Einstein condensate from a Bardeen-Cooper-Schrieffer (BCS) state of fermionic atoms.
- To investigate the dynamics of condensate growth by slowly sweeping through a Feshbach resonance.
- To compare the theoretical findings with phenomenological models like the time-dependent Ginzburg-Landau theory.
Main Methods:
- Application of a path integral approach for molecular fields.
- Utilizing two-body adiabatic approximations to solve atomic evolution under classical molecular fields.
- Employing saddle point approximation in the narrow resonance limit for semiclassical analysis of condensate growth.
Main Results:
- Derivation of an effective action for molecules based on atomic evolution.
- Detailed description of the time-dependent growth of the molecular condensate.
- The process is shown to be analogous to the cosmological Zurek scenario.
Conclusions:
- The study provides a rigorous theoretical framework for understanding molecular BEC formation from fermionic atoms.
- The findings offer a detailed comparison between the derived theory and phenomenological descriptions.
- This work deepens the understanding of quantum phase transitions and condensate dynamics in driven quantum systems.
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