Observation of dynamical fermionization

Area of Science:

• Quantum physics
• Condensed matter physics
• Atomic, molecular, and optical physics

Background:

• The Tonks-Girardeau (T-G) gas, a model of strongly interacting bosons in one dimension, shares similarities with noninteracting Fermi gases due to fermionization.
• Despite fermionization, equilibrium momentum distributions of T-G and Fermi gases differ significantly.

Purpose of the Study:

• To experimentally observe and characterize dynamical fermionization in a T-G gas.
• To investigate the momentum distribution evolution after releasing axial confinement and changing trap depth.
• To compare experimental results with theoretical predictions for T-G gases.

Main Methods:

• Creation and manipulation of a one-dimensional Tonks-Girardeau gas of ultracold atoms.
• In-situ imaging techniques to measure the momentum distribution of the gas.
• Controlled release of axial confinement and sudden changes to trap potential depth.

Main Results:

• Observed dynamical fermionization: the momentum distribution of the T-G gas evolved from bosonic to fermionic after axial confinement was removed.
• Measured the asymptotic momentum distribution after expansion, identifying it as the distribution of rapidities.
• Observed bosonic-fermionic oscillations in momentum distribution after altering trap depth, consistent with theoretical predictions.

Conclusions:

• Experimental evidence supports the theory of dynamical fermionization in one-dimensional Tonks-Girardeau gases.
• The study confirms the role of rapidities in the asymptotic momentum distribution of expanded T-G gases.
• The observed oscillations provide further validation for T-G gas theory under dynamic conditions.