Phase coherence of an atomic Mott insulator

Area of Science:

• Quantum physics
• Atomic physics
• Condensed matter physics

Background:

• Ultracold Bose gases in optical lattices are crucial for studying quantum phenomena.
• The Mott insulating phase is a key state characterized by strong correlations and suppressed quantum fluctuations.

Purpose of the Study:

• To investigate the phase coherence properties of ultracold Bose gases.
• To specifically analyze coherence within the Mott insulating phase.

Main Methods:

• Experimental realization of ultracold Bose gases in optical lattices.
• Observation of interference patterns after free expansion to probe phase coherence.
• Analysis of visibility and its dependence on system parameters.

Main Results:

• Phase coherence persists on short length scales deep within the Mott insulating phase.
• Finite interference pattern visibility is observed, indicating residual coherence.
• Reproducible kinks in visibility suggest density redistribution in the trapped Mott insulator's shell structure.

Conclusions:

• Short-range phase coherence is a robust feature of the Mott insulating phase.
• Coherent particle-hole admixtures explain the observed persistence of coherence.
• Kinks in visibility serve as signatures for shell structure effects in trapped Mott insulators.