Calorimetry of a harmonically trapped Bose gas

Abstract

We experimentally study the energy-temperature relationship of a harmonically trapped BoseEinstein condensate by transferring a known quantity of energy to the condensate and measuring the resulting temperature change. We consider two methods of heat transfer, the first using a free expansion under gravity and the second using an optical standing wave to diffract the atoms in the potential. We investigate the effect of interactions on the thermodynamics and compare our results to various finite temperature theories.

Thermalization, condensate growth, and defect formation in an out-of-equilibrium Bose gas

“…an extra 23% of N = 2 × 10 4 particles). Due to the quantum degeneracy, the continued center of mass motion, the We perform a fit to the density profile consisting of a Thomas-Fermi profile for the condensed atoms, a Bose-Enhanced Gaussian for the non-condensed atoms [26,27], as well as a characteristic gray soliton profile.…”

“…4(b). Here we have applied a fit of a Thomas-Fermi profile for the condensed atoms, a Bose-enhanced Gaussian for the non-condensed atoms [26,27], and a characteristic tanh 2 [(y − y 0 )/σ s ] profile for the gray soliton, where y 0 is the soliton offset and σ s is related to the soliton width. We perform multiple experiments having t = 15 ms of evolution, from which we find 20% of images containing features that we are able to readily identify as solitons.…”

“…The image is taken after t = 15 ms of in-potential evolution with trap frequency ωy/(2π) = 280 Hz. (b) Integrating a strip of the atomic density reveals the nature of the soliton.We perform a fit to the density profile consisting of a Thomas-Fermi profile for the condensed atoms, a Bose-Enhanced Gaussian for the non-condensed atoms[26,27], as well as a characteristic gray soliton profile.…”

Characterizing real-space topology in Rice-Mele model by thermodynamics

“…Calorimetric studies have long been valuable tools for rigorous tests of physical law [37,38,[44][45][46][47][48][49][50][51][52][53], such as the measurements of heat capacity, entropy, and isothermal compressibility of BEC. To measure the heat capacity, we have to transfer a known quantity of energy to the BEC and measure the resulting temperature change.…”

“…The energy can be precisely added to the atoms by releasing the cloud from the trap with the influence of gravity and permitting it to expand for a short time t heat (typically 0 ∼ 1000µs), after which the atoms are recaptured and rethermalized [37,52]. The transferred energy is comprised of three contributions: (i) the atoms fall under gravity and gain kinetic energy; (ii) the displacement h = 1 2 gt 2 heat during fall leads to a potential energy gain when the trap is reinstated; and (iii) the larger cloud size after the expansion results in greater potential energy when the trap potential is restored.…”