Generalized Moment Method for Gap Estimation and Quantum Monte Carlo Level Spectroscopy

Understand

We formulate a convergent sequence for the energy gap estimation in the worldline quantum Monte Carlo method.

• The ambiguity left in the conventional gap calculation for quantum systems is eliminated.
• Our estimation will be unbiased in the low-temperature limit and also the error bar is reliably estimated.
• The level spectroscopy from quantum Monte Carlo data is developed as an application of the unbiased gap estimation.