  Quantum Monte Carlo (QMC) techniques are widely used in a variety of
scientific problems and much work has been dedicated to developing optimized
algorithms that can accelerate QMC on standard processors (CPU). With the
advent of various special purpose devices and domain specific hardware, it has
become increasingly important to establish clear benchmarks of what
improvements these technologies offer compared to existing technologies. In
this paper, we demonstrate 2 to 3 orders of magnitude acceleration of a
standard QMC algorithm using a specially designed digital processor, and a
further 2 to 3 orders of magnitude by mapping it to a clockless analog
processor. Our demonstration provides a roadmap for 5 to 6 orders of magnitude
acceleration for a transverse field Ising model (TFIM) and could possibly be
extended to other QMC models as well. The clockless analog hardware can be
viewed as the classical counterpart of the quantum annealer and provides
performance within a factor of $<10$ of the latter. The convergence time for
the clockless analog hardware scales with the number of qubits as $\sim N$,
improving the $\sim N^2$ scaling for CPU implementations, but appears worse
than that reported for quantum annealers by D-Wave.
