arXiv:2212.13220 · Physical Review A

Mitigating heating of degenerate fermions in a ring-dimple atomic trap

Daniel Allman, Parth Sabharwal, Kevin Wright

Published Apr 25, 2023• 5 citations

Abstract

We report on the impact of the extended geometry of a ring-dimple trap on particle-loss heating of a degenerate Fermi gas. When the Fermi level is slightly greater than the depth of the dimple and a broad, low-density ``halo'' is present, the overall heating rate is reduced relative to the case of a bare ring. We find that the experimentally measured heating rates for the overfilled dimple are in good agreement with a model of the hole-induced heating caused by background-gas collisions. This suppression of the heating rate can be helpful for experimental studies of fermionic superfluids in the weak pairing limit, where achieving and maintaining low temperatures over long timescales are essential.

DOI: 10.1103/physreva.107.043322

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arXiv:2212.13220 · Physical Review A

Mitigating heating of degenerate fermions in a ring-dimple atomic trap

Daniel Allman, Parth Sabharwal, Kevin Wright

Published Apr 25, 2023• 5 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physreva.107.043322

Related papers

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E.A.H. Timmermans

Loss processes that remove particles from an atom trap leave holes behind in the single particle distribution if the trapped gas is a degenerate fermion system. The appearance of holes increases the temperature and we show that the heating (i) is significant if the initial temperature is well below the Fermi temperature T(F), and (ii) increases the temperature to T> or =T(F)/4 after half of the system's lifetime, regardless of the initial temperature. The hole heating has important consequences for the prospect of observing Cooper pairing in atom traps.Loss processes that remove particles from an atom trap leave holes behind in the single particle distribution if the trapped gas is a degenerate fermion system. The appearance of holes increases the temperature and we show that the heating (i) is significant if the initial temperature is well below the Fermi temperature T(F), and (ii) increases the temperature to T> or =T(F)/4 after half of the system's lifetime, regardless of the initial temperature. The hole heating has important consequences for the prospect of observing Cooper pairing in atom traps.

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Sympathetic cooling of trapped fermions by bosons in the presence of particle losses

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Chenchong Zhu, James L. Booth, Kirk W. Madison

Heating in a magnetic trap was observed through measurements of heated fraction. These results are in agreement with a trap simulation, which can also be used to predict per-atom heating rate . The heating rate for an ensemble with non-zero temperature is significantly smaller than the heating rate for an ensemble with zero temperature. Future work includes refining FH’ measurements, investigating possible deviations of the data from the simulation at large trap depths, and characterizing heating between trapped Rb and other gases, such as 40Ar. dt dE /Heating in a magnetic trap was observed through measurements of heated fraction. These results are in agreement with a trap simulation, which can also be used to predict per-atom heating rate . The heating rate for an ensemble with non-zero temperature is significantly smaller than the heating rate for an ensemble with zero temperature. Future work includes refining FH’ measurements, investigating possible deviations of the data from the simulation at large trap depths, and characterizing heating between trapped Rb and other gases, such as 40Ar. dt dE /

Bulletin of the American Physical SocietyMay 27, 20100 citations

We investigate a species selective cooling process of a trapped

\mathrm{SU}(N)

Fermi gas using entropy redistribution during adiabatic loading of an optical lattice. Using high-temperature expansion of the Hubbard model, we show that when a subset

{N}_{A}<N

of the single-atom levels experiences a stronger trapping potential in a certain region of space, the dimple, it leads to improvement in cooling as compared to an

\mathrm{SU}({N}_{A})

Fermi gas only. We show that optimal performance is achieved when all atomic levels experience the same potential outside the dimple and we quantify the cooling for various

{N}_{A}

by evaluating the dependence of the final entropy densities and temperatures as functions of the initial entropy. Furthermore, considering

^{87}\mathrm{Sr}

and

^{173}\mathrm{Yb}

for specificity, we provide a quantitative discussion of how the state selective trapping can be achieved with readily available experimental techniques.