Technical thermodynamics of an inhomogeneous gas around the Bose-Einstein transition using the global-variable method

Miotti, Marcos Paulo

doi:10.11606/d.76.2021.tde-22112021-093755

Cited by 1 publication

(4 citation statements)

References 32 publications

(54 reference statements)

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“…By designing an empirical expression for the equation of state in Eq. (7) and fitting it to significantly large dataset of measurements, we have been able to obtain entropy directly and find that its value is constant at the transition, confirming the known inexistence of latent heat for BEC.…”

Section: Discussionsupporting

confidence: 60%

“…Our experimental setup for producing rubidium-87 ( 87 Rb) gas samples under BEC is the well-known double magneto-optical trap (MOT) system, whose construction and operation are detailed in Chapter 4 of Ref. [7]. In summary, hot 87 Rb gas is initially collected at the first MOT and transferred to the second MOT, in which the gas is cooled to millikelvins.…”

Section: Thermodynamic Experimentsmentioning

confidence: 99%

“…In the last year [6], we demonstrated theoretically and experimentally that the efficiency of Carnot cycles is always 1 − T cold /T hot before, across and after BEC, therefore showing that result to hold true in both classical and quantum regimes, as well as in the transition between them. For that end, we have used experimental data and the methodology firstly described on the corresponding author's Master thesis [7], which relied on a formalism called Global-Variable Method [8][9][10], an approach parallel to Local Density Approximation [11] in describing the thermodynamics of inhomogeneous quantum gases (remarkably, the harmonically trapped ones). Now, using the same data and approach, we present here a strictly experimental investigation on the BEC transition as a energy source for non-mechanical work, a topic is seldomly explored in literature.…”

Section: Introductionmentioning

confidence: 99%

“…(2)) as temperature decreases. The blue, red and green lines represent the components of our empirical model for the equation of state, seen in Eq (7)…”

mentioning

confidence: 99%

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Entropy and Energy for Non-Mechanical Work at the Bose-Einstein Transition of a Harmonically Trapped Gas Using an Empirical Global-Variable Method

Miotti,

Martins,

Hemmerling

et al. 2024

Preprint

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Quantum thermal engines are receiving much attention in recent years, due to their potential applications.~For a candidate group, harmonically trapped gases under Bose-Einstein condensation (BEC), we see little investigation on the energy transference around that transition.~Therefore, we present an empirical study with rubidium-87 gas samples in a magnetic harmonic trap.~We developed an empirical Equation of State model to fit to our experimental dataset, expressing the pressure parameter ($\mathcal{P}$) in terms of temperature ($T$) and six technical coeffcients ($\{a_i\}_{0,\dots,4}$, $T_\mathrm{th}$), functions of volume parameter ($\mathcal{V}$) and number of atoms ($N$).~For weakly interacting gases, the internal energy is $U\cong3\mathcal{P}\mathcal{V}$, thus we determine the entropy with $U = TS - \mathcal{P}\mathcal{V}$ for fixed $N$.~As expected, we show that the entropy at the BEC transition ($S_c$) is constant for varying $\mathcal{V}$.~Being isentropic makes BEC transition an energy source for non-mechanical work.~Hence, we observed that the enthalpy at the BEC transition $H_c = E_c + \mathcal{P}_c\mathcal{V} = T_cS_c$, at fixed values of $\mathcal{V}$ and varying $N$, grows fairly linearly with $N$.~We fitted $H_c=\eta{N}-H_c^0$ to that data, being $\eta$ the specific enthalpy of BEC transformation and $H_c^0$ an intrinsic enthalpic loss.~We deem this study to be a step closer to practical quantum-based engines.

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Section: Discussionsupporting

confidence: 60%

Section: Thermodynamic Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…(2)) as temperature decreases. The blue, red and green lines represent the components of our empirical model for the equation of state, seen in Eq (7)…”

mentioning

confidence: 99%

See 2 more Smart Citations

Entropy and Energy for Non-Mechanical Work at the Bose-Einstein Transition of a Harmonically Trapped Gas Using an Empirical Global-Variable Method

Miotti,

Martins,

Hemmerling

et al. 2024

Preprint

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show abstract

Technical thermodynamics of an inhomogeneous gas around the Bose-Einstein transition using the global-variable method

Abstract: MIOTTI, M. P. Technical thermodynamics of an inhomogeneous gas around the Bose-Einstein transition using the global-variable method. 2021. 165p. Dissertation (Master in Science) -

Cited by 1 publication

References 32 publications

Entropy and Energy for Non-Mechanical Work at the Bose-Einstein Transition of a Harmonically Trapped Gas Using an Empirical Global-Variable Method

Entropy and Energy for Non-Mechanical Work at the Bose-Einstein Transition of a Harmonically Trapped Gas Using an Empirical Global-Variable Method

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