Quantum tunneling and anti-tunneling across entropic barriers

TL;DR

This paper investigates how quantum effects influence particle transport in a narrow, disorder-free channel, revealing an unexpected anti-tunneling phenomenon where quantum corrections inhibit current at certain temperatures.

Contribution

It demonstrates the counterintuitive anti-tunneling effect in quantum transport through entropic barriers, combining numerical and analytical approaches.

Findings

Quantum corrections can inhibit particle transport at intermediate temperatures.

The anti-tunneling effect is confirmed both numerically and analytically.

Transport behavior deviates from naive expectations of enhanced tunneling at lower temperatures.

Abstract

We study the dynamics of a quantum particle in a constricted two-dimensional channel and analyze how the onset of quantum corrections impacts the (semi-)classical high-temperature behaviour, as temperature is lowered. We characterize both equilibrium and non-equilibrium (transport) properties of the system, considering the case of a narrow and disorder-free channel. Counterintuitively, we find that quantum corrections do not monotonically enhance the particle current as the temperature is lowered, as naively expected from the activation of coherent tunnelling, but they rather inhibit transport at intermediate temperatures, increasing the effective free-energy barrier. We illustrate this ``anti-tunnelling'' effect numerically by computing the non-equilibrium steady-state of a quantum master equation describing the system, and confirm it analytically by adopting the Quantum Smoluchowski limit.