论文标题
二维费米气体强度相关方案中的伪效应
Pseudogap effects in the strongly correlated regime of the two-dimensional Fermi gas
论文作者
论文摘要
在两个空间维度上具有吸引人的短距离相互作用的两个物种的费米气体为理解二维中强相关的费米超流体提供了一个范式的系统。众所周知，它可以显示出BEC-BCS跨界车的函数（k_f a）$，其中$ a $是散射长度，并且在关键温度$ t_c $的关键温度以下进行了berezinskii-kosterlitz-berezinskii-kosterlitz-无尽的超级流体过渡。但是，在$ \ ln（k_f a）\ sim 1 $的密切相关性方面的假单制度的程度，其中配对相关性持续在$ t_c $以上，在很大程度上未用受控的理论方法来探索。在这里，我们在规范合奏形式主义中使用离散的晶格中使用有限的辅助场量子蒙特卡洛（AFMC）方法来计算密切相关的状态中的热力学可观察物。我们推断到连续时间和连续限制，以消除系统错误，并为粒子数量从$ n = 42 $到$ n = 162 $提供结果。我们通过有限大小的缩放分析估算$ t_c $，并在旋转易感性和自由能差距中观察到清晰的伪签名和低于温度的$ t^*$。我们还提出了接触的结果，这是具有短距离相互作用的量子多体系统的基本热力学特性。
The two-species Fermi gas with attractive short-range interactions in two spatial dimensions provides a paradigmatic system for the understanding of strongly correlated Fermi superfluids in two dimensions. It is known to exhibit a BEC-BCS crossover as a function of $\ln(k_F a)$, where $a$ is the scattering length, and to undergo a Berezinskii-Kosterlitz-Thouless superfluid transition below a critical temperature $T_c$. However, the extent of a pseudogap regime in the strongly correlated regime of $\ln(k_F a)\sim 1$, in which pairing correlations persist above $T_c$, remains largely unexplored with controlled theoretical methods. Here we use finite-temperature auxiliary-field quantum Monte Carlo (AFMC) methods on discrete lattices in the canonical ensemble formalism to calculate thermodynamical observables in the strongly correlated regime. We extrapolate to continuous time and the continuum limit to eliminate systematic errors and present results for particle numbers ranging from $N=42$ to $N=162$. We estimate $T_c$ by a finite-size scaling analysis, and observe clear pseudogap signatures above $T_c$ and below a temperature $T^*$ in both the spin susceptibility and free-energy gap. We also present results for the contact, a fundamental thermodynamic property of quantum many-body systems with short-range interactions.
