Transverse demagnetization dynamics of a unitary Fermi gas.
Understanding the quantum dynamics of strongly interacting fermions is a problem relevant to diverse forms of matter, including high-temperature superconductors, neutron stars, and quark-gluon plasma. An appealing benchmark is offered by cold atomic gases in the unitary limit of strong interactions. Here, we study the dynamics of a transversely magnetized unitary Fermi gas in an inhomogeneous magnetic field. We observe the demagnetization of the gas, caused by diffusive spin transport. At low temperatures, the diffusion constant saturates to the conjectured quantum-mechanical lower bound ≃ ħ/m, where m is the particle mass. The development of pair correlations, indicating the transformation of the initially noninteracting gas toward a unitary spin mixture, is observed by measuring Tan's contact parameter.
Department of Physics, University of Toronto, M5S 1A7 Canada.
A B
AB
Bardon
Department of Physics, University of Toronto, M5S 1A7 Canada.
S
S
Beattie
Department of Physics, University of Toronto, M5S 1A7 Canada.
C
C
Luciuk
Department of Physics, University of Toronto, M5S 1A7 Canada.
W
W
Cairncross
Department of Physics, University of Toronto, M5S 1A7 Canada.
D
D
Fine
Department of Physics, University of Toronto, M5S 1A7 Canada.
N S
NS
Cheng
Department of Physics, University of Toronto, M5S 1A7 Canada.
G J A
GJ
Edge
Department of Physics and Astronomy, McMaster University, L8S 4M1 Canada.
E
E
Taylor
Department of Physics, Center of Theoretical and Computational Physics, University of Hong Kong, China.
S
S
Zhang
Department of Physics, University of Toronto, M5S 1A7 Canada.
S
S
Trotzky
Department of Physics, University of Toronto, M5S 1A7 Canada. Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1Z8 Canada. joseph.thywissen@utoronto.ca.
J H
JH
Thywissen