Quantum-classical transition and quantum activation of ratchet currents in the parameter space

TL;DR

This paper investigates how quantum fluctuations influence ratchet currents in a dissipative kicked rotor, revealing quantum effects like barrier overcoming and activation regions, contrasting classical and semiclassical behaviors.

Contribution

It introduces a detailed analysis of quantum, semiclassical, and classical dynamics in the quantum ratchet system, highlighting the role of quantum fluctuations in current activation.

Findings

Quantum fluctuations blur classical stable structures.

Quantum fluctuations help overcome phase space barriers.

Quantum activation regions are identified in parameter space.

Abstract

The quantum ratchet current is studied in the parameter space of the dissipative kicked rotor model coupled to a zero temperature quantum environment. We show that vacuum fluctuations blur the generic isoperiodic stable structures found in the classical case. Such structures tend to survive when a measure of statistical dependence between the quantum and classical currents are displayed in the parameter space. In addition, we show that quantum fluctuations can be used to overcome transport barriers in the phase space. Related quantum ratchet current activation regions are spotted in the parameter space. Results are discussed {based on quantum, semiclassical and classical calculations. While the semiclassical dynamics involves vacuum fluctuations, the classical map is driven by thermal noise.