Quantitative comparison between theoretical predictions and experimental results for the BCS-BEC crossover

Area of Science:

• Atomic physics
• Quantum mechanics
• Condensed matter physics

Background:

• Understanding the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein Condensation (BEC) crossover is crucial for ultracold atomic gases.
• Trapped Fermi atoms provide a unique system to study this quantum phase transition.
• Previous theoretical models often simplified pairing fluctuations, limiting accuracy.

Purpose of the Study:

• To compare theoretical predictions for the BCS-BEC crossover in trapped Fermi atoms with experimental data.
• To validate a theoretical approach incorporating pairing fluctuations beyond mean-field.
• To assess the accuracy of theoretical predictions for key thermodynamic quantities at the unitarity limit.

Main Methods:

• Utilized a single theoretical framework accounting for pairing fluctuations beyond mean-field theory.
• Compared theoretical density profiles with experimental results for Lithium-6 (6Li) atoms.
• Evaluated zero-temperature chemical potential and gap predictions against Quantum Monte Carlo simulations and experimental data.

Main Results:

• Achieved excellent agreement between theoretical predictions and experimental density profiles of trapped 6Li atoms.
• The theoretical approach accurately captures the behavior across the BCS-BEC crossover.
• Theoretical predictions for chemical potential and gap at unitarity show strong agreement with simulations and experiments.

Conclusions:

• The theoretical approach, including pairing fluctuations, successfully describes the BCS-BEC crossover in Fermi atoms.
• Experimental validation confirms the predictive power of the model for ultracold atomic gases.
• The findings provide a reliable theoretical tool for studying strongly interacting Fermi systems.