Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Frontiers in Optics

Spatial Deformation in a Phase Separated Fermi Gas

Guthrie B. Partridge, W. Li, Yunxiang Liao, Ngoc Duy Nguyen, Ramsey I. Kamar, Randall G. Hulet

Published Jan 1, 2006• 1 citation
Publisher

Abstract

Phase separation between a uniformly paired core and excess unpaired atoms is observed in a two component strongly interacting ultra-cold gas of fermionic 6Li. Spatial deformations in the density distributions violate the local density approximation.
DOI
10.1364/ls.2006.lmc3

Related papers

Deformation of a Trapped Fermi Gas with Unequal Spin Populations

Guthrie B. Partridge, Wenhui Li, Yunxiang Liao +3 more

The real-space densities of a polarized strongly interacting two-component Fermi gas of 6Li atoms reveal two low-temperature regimes, both with a fully paired core. At the lowest temperatures, the unpolarized core deforms with increasing polarization. Sharp boundaries between the core and the excess unpaired atoms are consistent with a phase separation driven by a first-order phase transition. In contrast, at higher temperatures the core does not deform but remains unpolarized up to a critical polarization. The boundaries are not sharp in this case, indicating a partially polarized shell between the core and the unpaired atoms. The temperature dependence is consistent with a tricritical point in the phase diagram.

arXiv:cond-mat/0608455•Physical Review Letters•Nov 10, 2006•262 citations

Phases of a Paired Fermi Gas with Unequal Spin Populations

Guthrie B. Partridge, Wenhui Li, Yean-an Liao +1 more

We have produced a two-component gas of ultracold, fermionic 6Li atoms with unequal spin populations. The real-space densities reveal two distinct superfluid phases, both with an evenly paired central core.

Quantum Electronics and Laser Science Conference•May 6, 2007•0 citations

POLARIZED ATOMIC FERMI GASES

Wenhui Li, Guthrie B. Partridge, Yunxiang Liao +1 more

We review recent experimental studies on polarized atomic Fermi gases. The particular focus is on our own experiments of strongly interacting two-component Fermi gases with imbalanced populations. The real-space density distributions reveal a superfluid/normal phase separation at very low temperatures, accompanied by deformation of evenly paired core; at higher temperatures, a partially polarized phase is observed.

International Journal of Modern Physics B•Jun 20, 2009•5 citations

Phases of a fermi gas with unequal spin populations

Guthrie B. Partridge, Wenhui Li, Yean-an Liao +1 more

We have produced a two-component gas of ultracold, fermionic 6Li atoms with unequal spin populations. The real-space densities reveal two distinct superfluid phases, both with an evenly paired central core.

Quantum Electronics and Laser Science Conference•May 1, 2007•0 citations

Fermion Pairing with Unequal Spin Populations

Randall G. Hulet, Guthrie B. Partridge, Wenhui Li +1 more

We have produced a two-component gas of ultracold, fermionic 6Li atoms with unequal spin populations. The real-space densities reveal a superfluid/normal phase separation at very low temperatures, and a partially polarized paired phase at higher temperatures.

The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting•Jan 1, 2007•0 citations

Pairing of fermionic lithium-6 throughout the BEC-BCS crossover

Guthrie B. Partridge

The pairing of fermionic particles is an essential ingredient of superconductivity and of the superfluidity of 3He. While such phenomena are accurately described by BCS theory in the limit of weak pairing strength, a complete understanding remains elusive when pairing strength is increased, such as in high temperature superconductors. We create ultracold gases of trapped fermionic 6Li atoms, through which we directly observe fermionic pairing. In our system, there are no impurities whatsoever, and parameters such as the number and temperature of the trapped atoms are precisely and independently controlled. In addition, a Feshbach resonance enables the continuous tuning of interaction strength and sign between the paired atoms. This control allows us to observe the smooth crossover of a molecular Bose Einstein condensate (MBEC) to a superfluid of weakly interacting Cooper pairs. With these tools, we have performed several fundamental measurements of pairing in fermionic systems.\nWe use optical molecular spectroscopy to precisely measure the closed-channel contribution to the many body state of paired 6Li atoms within a broad Feshbach resonance. The magnitude of this contribution is small, and supports the concept of universality for the description of broad Feshbach resonances. Moreover, the dynamics of the excitation provide clear evidence for pairing across the BEC-BCS crossover, and for the first time, into the weakly interacting BCS regime.\nWe also prepare a polarized Fermi gas with unequal numbers of two spin states of 6Li atoms. The real-space densities of the polarized, strongly-interacting, two-component Fermi gas reveal two low temperature regimes. At the lowest temperatures, the gas separates into a phase with a uniformly paired superfluid core surrounded by a shell of normal, unpaired atoms. This phase separation is accompanied by a spatial deformation of the core. At higher temperatures, the uniformly paired core persists, though it does not deform. This temperature dependence is consistent with a tri-critical point in the phase diagram. These measurements of pairing in a polarized Fermi gas are relevant to predictions of exotic phases of quark matter and magnetized superconductors.

•Jan 1, 2007•0 citations
The real-space densities of a polarized strongly interacting two-component Fermi gas of 6Li atoms reveal two low-temperature regimes, both with a fully paired core. At the lowest temperatures, the unpolarized core deforms with increasing polarization. Sharp boundaries between the core and the excess unpaired atoms are consistent with a phase separation driven by a first-order phase transition. In contrast, at higher temperatures the core does not deform but remains unpolarized up to a critical polarization. The boundaries are not sharp in this case, indicating a partially polarized shell between the core and the unpaired atoms. The temperature dependence is consistent with a tricritical point in the phase diagram.
The pairing of fermionic particles is an essential ingredient of superconductivity and of the superfluidity of 3He. While such phenomena are accurately described by BCS theory in the limit of weak pairing strength, a complete understanding remains elusive when pairing strength is increased, such as in high temperature superconductors. We create ultracold gases of trapped fermionic 6Li atoms, through which we directly observe fermionic pairing. In our system, there are no impurities whatsoever, and parameters such as the number and temperature of the trapped atoms are precisely and independently controlled. In addition, a Feshbach resonance enables the continuous tuning of interaction strength and sign between the paired atoms. This control allows us to observe the smooth crossover of a molecular Bose Einstein condensate (MBEC) to a superfluid of weakly interacting Cooper pairs. With these tools, we have performed several fundamental measurements of pairing in fermionic systems.\nWe use optical molecular spectroscopy to precisely measure the closed-channel contribution to the many body state of paired 6Li atoms within a broad Feshbach resonance. The magnitude of this contribution is small, and supports the concept of universality for the description of broad Feshbach resonances. Moreover, the dynamics of the excitation provide clear evidence for pairing across the BEC-BCS crossover, and for the first time, into the weakly interacting BCS regime.\nWe also prepare a polarized Fermi gas with unequal numbers of two spin states of 6Li atoms. The real-space densities of the polarized, strongly-interacting, two-component Fermi gas reveal two low temperature regimes. At the lowest temperatures, the gas separates into a phase with a uniformly paired superfluid core surrounded by a shell of normal, unpaired atoms. This phase separation is accompanied by a spatial deformation of the core. At higher temperatures, the uniformly paired core persists, though it does not deform. This temperature dependence is consistent with a tri-critical point in the phase diagram. These measurements of pairing in a polarized Fermi gas are relevant to predictions of exotic phases of quark matter and magnetized superconductors.