Effects of particle-hole fluctuations on the superfluid transition in two-dimensional atomic Fermi gases

Fuente: arXiv
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Autori principali: Wu, Junru, Wang, Zongpu, Sun, Lin, Zhang, Kaichao, Li, Chuping, Wu, Yuxuan, Chen, Pengyi, Yuan, Dingli, Chen, Qijin
Natura: Preprint
Pubblicazione: 2025
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author Wu, Junru
Wang, Zongpu
Sun, Lin
Zhang, Kaichao
Li, Chuping
Wu, Yuxuan
Chen, Pengyi
Yuan, Dingli
Chen, Qijin
author_facet Wu, Junru
Wang, Zongpu
Sun, Lin
Zhang, Kaichao
Li, Chuping
Wu, Yuxuan
Chen, Pengyi
Yuan, Dingli
Chen, Qijin
contents Proper treatment of the many-body interactions is of paramount importance in our understanding of strongly correlated systems. Here we investigate the effects of particle-hole fluctuations on the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional Fermi gases throughout the entire BCS-BEC crossover. We include self-consistently in the self energy treatment the entire particle-hole $T$ matrix, which constitutes a renormalization of the bare interaction that appears in the particle-particle scattering $T$ matrix, leading to a screening of the pairing interaction and hence a dramatic reduction of the pairing gap and the transition temperature. The BKT transition temperature $T_\text{BKT}$ is determined by the critical phase space density, for which the pair density and pair mass are determined using a pairing fluctuation theory, which accommodates self-consistently the important self-energy feedback in the treatment of finite-momentum pairing fluctuations. The screening strength varies continuously from its maximum in the BCS limit to essentially zero in BEC limit. In the unitary regime, it leads to an interaction-dependent shift of $T_\text{BKT}$ towards the BEC regime. This shift is crucial in an attempt to explain experimental data quantitatively, which often depends on the interaction strength. Our findings are consistent with available experimental results in the unitary and BEC regimes and with quantum Monte Carlo simulations in the BCS and unitary regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23061
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effects of particle-hole fluctuations on the superfluid transition in two-dimensional atomic Fermi gases
Wu, Junru
Wang, Zongpu
Sun, Lin
Zhang, Kaichao
Li, Chuping
Wu, Yuxuan
Chen, Pengyi
Yuan, Dingli
Chen, Qijin
Quantum Gases
Strongly Correlated Electrons
Superconductivity
Proper treatment of the many-body interactions is of paramount importance in our understanding of strongly correlated systems. Here we investigate the effects of particle-hole fluctuations on the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional Fermi gases throughout the entire BCS-BEC crossover. We include self-consistently in the self energy treatment the entire particle-hole $T$ matrix, which constitutes a renormalization of the bare interaction that appears in the particle-particle scattering $T$ matrix, leading to a screening of the pairing interaction and hence a dramatic reduction of the pairing gap and the transition temperature. The BKT transition temperature $T_\text{BKT}$ is determined by the critical phase space density, for which the pair density and pair mass are determined using a pairing fluctuation theory, which accommodates self-consistently the important self-energy feedback in the treatment of finite-momentum pairing fluctuations. The screening strength varies continuously from its maximum in the BCS limit to essentially zero in BEC limit. In the unitary regime, it leads to an interaction-dependent shift of $T_\text{BKT}$ towards the BEC regime. This shift is crucial in an attempt to explain experimental data quantitatively, which often depends on the interaction strength. Our findings are consistent with available experimental results in the unitary and BEC regimes and with quantum Monte Carlo simulations in the BCS and unitary regimes.
title Effects of particle-hole fluctuations on the superfluid transition in two-dimensional atomic Fermi gases
topic Quantum Gases
Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2510.23061