Thermometry of a deeply degenerate Fermi gas with a Bose-Einstein condensate

Rianne S. Lous, Isabella Fritsche, Michael Jag, Bo Huang (黄博), and Rudolf Grimm
Phys. Rev. A 95, 053627 – Published 23 May 2017

Abstract

We measure the temperature of a deeply degenerate Fermi gas, by using a weakly interacting sample of heavier bosonic atoms as a probe. This thermometry method relies on the thermalization between the two species and on the determination of the condensate fraction of the bosons. In our experimental implementation, a small sample of K41 atoms serves as the thermometer for a Li6 Fermi sea. We investigate the evaporative cooling of a Li6 spin mixture in a single-beam optical dipole trap and observe how the condensate fraction of the thermometry atoms depends on the final trap depth. From the condensate fraction, the temperature can be readily extracted. We show that the lowest temperature of 5.9(5)% of the Fermi temperature is obtained, when the decreasing trap depth closely approaches the Fermi energy. To understand the systematic effects that may influence the results, we carefully investigate the role of the number of bosons and the thermalization dynamics between the two species. Our thermometry approach provides a conceptually simple, accurate, and general way to measure the temperature of deeply degenerate Fermi gases. Since the method is independent of the specific interaction conditions within the Fermi gas, it applies to both weakly and strongly interacting Fermi gases.

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  • Received 9 February 2017

DOI:https://doi.org/10.1103/PhysRevA.95.053627

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied PhysicsAtomic, Molecular & Optical

Authors & Affiliations

Rianne S. Lous1,2, Isabella Fritsche1,2, Michael Jag1,2, Bo Huang (黄博)1, and Rudolf Grimm1,2

  • 1Institut für Quantenoptik und Quanteninformation (IQOQI), Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
  • 2Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria

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Issue

Vol. 95, Iss. 5 — May 2017

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