Quantum Monte Carlo without random numbers

Real-time diagrammatic quantum Monte Carlo (DiagQMC) is one of the few methods able to treat quantum impurity problem out of equilibrium. Like all Monte Carlo methods, it remains hindered by a convergence rate of one over square root of the number of calculated points (1/N^0.5). In recent work, we replaced the Metropolis algorithm and adapted DiagQMC to a Quasi-Monte Carlo integration method, where integration is performed using deterministic low discrepancy sequences [1]. We obtained convergence rate of one over the number of calculated points (1/N) and showed speed-ups of several orders of magnitude for favourable parameters.
In this talk, I will present novel results where the quantum impurity is embedded in a non-trivial environment, such as electron interferometer.

[1] Phys. Rev. Lett. 125 047702 (2020)