Quantum Monte Carlo (QMC) simulations of correlated electron systems provide unbiased information about system behavior at a quantum critical point (QCP) and can verify or disprove the existing theories of non-Fermi liquid (NFL) behavior at a QCP. However, simulations are carried out at a finite temperature, where quantum critical features are masked by finite-temperature effects. Here, we present a theoretical framework within which it is possible to separate thermal and quantum effects and extract the information about NFL physics at T = 0. We demonstrate our method for a specific example of 2D fermions near an Ising ferromagnetic QCP. We show that one can extract from QMC data the zero-temperature form of fermionic self-energy Σ(ω) even though the leading contribution to the self-energy comes from thermal effects. We find that the frequency dependence of Σ(ω) agrees well with the analytic form obtained within the Eliashberg theory of dynamical quantum criticality, and obeys ω^2/3 scaling at low frequencies. Our results open up an avenue for QMC studies of quantum critical metals.

相关电子系统的量子蒙特卡洛（QMC）模拟提供了有关量子临界点（QCP）处系统行为的无偏信息，并且可以验证或证明QCP处非费米液体（NFL）行为的现有理论。但是，模拟是在有限的温度下进行的，其中量子临界特征被有限的温度效应所掩盖。在这里，我们提供了一个理论框架，可以在其中分离热效应和量子效应，并提取有关T = 0时NFL物理学的信息。我们为伊辛铁磁QCP附近的二维费米子的一个特定示例演示了我们的方法。我们表明，可以从QMC数据中提取铁电自能量Σ（ω），尽管自能量的主要贡献来自热效应。我们发现，Σ（ω）的频率依赖性与在Eliashberg动态量子临界理论中获得的解析形式非常吻合，并且在低频时服从ω2 ^/3缩放。我们的结果为量子临界金属的QMC研究开辟了道路。