Adding noise and scaling forces to speed up the Langevin clock

TL;DR

This paper experimentally confirms that scaling forces and adding noise can accelerate Langevin dynamics, enabling faster computations and more accurate free-energy measurements in thermodynamic computing.

Contribution

It demonstrates experimentally that force scaling and noise addition can speed up Langevin clocks and improve equilibrium approximation in nonequilibrium systems.

Findings

Increased effective mobility of Langevin systems confirmed experimentally.

Systems driven out of equilibrium can stay closer to thermal equilibrium.

Enhanced accuracy in free-energy difference estimation achieved.

Abstract

Using experiments on a colloidal particle trapped in an optical tweezer, we confirm a recent proposal to increase the effective mobility or clock rate of systems described by Langevin dynamics, by simultaneously scaling deterministic forces and adding external noise. A corollary, which we also confirm experimentally, is that a system driven out of equilibrium by a time-dependent protocol can remain closer to thermal equilibrium. As an application, we demonstrate more precise recovery of free-energy differences from nonequilibrium work relations. Langevin clock rescaling provides a general strategy for accelerating calculations in the emerging field of thermodynamic computing, which uses stochastic devices governed by Langevin dynamics to do low-energy calculations.