Discovery of energy landscapes towards optimized quantum transport: Environmental effects and long-range tunneling

TL;DR

This paper identifies optimal energy landscapes in quantum chains that enhance carrier transport by considering environmental effects, long-range tunneling, and system size, providing design insights for quantum transport systems.

Contribution

It introduces a systematic optimization approach for energy profiles in quantum chains, considering environmental effects and long-range couplings, to improve transport efficiency.

Findings

Different energy landscapes optimize transport depending on tunneling range.

Environmental interactions and temperature influence optimal energy profiles.

Systematic patterns in energy profiles emerge for larger systems.

Abstract

Carrier transport in quantum networks is governed by a variety of factors, including network dimensionality and connectivity, on-site energies, couplings between sites and whether they are short- or long-range, leakage processes, and environmental effects. In this work, we identify classes of quasi-one-dimensional chains with energy profiles that optimize carrier transport under such influences. Specifically, we optimize on-site energies using Optax's optimistic gradient descent and AdaMax algorithms, enabled by the JAX automatic differentiation framework. Focusing on nonequilibrium steady-state transport, we study the system's behavior under combined unitary and nonunitary (dephasing and dissipative) effects using the Lindblad quantum master equation. After validating our optimization scheme on short chains, we extend the study to larger systems where we identify systematic patterns in energy profiles. Our analysis reveals that different types of energy landscapes enhance transport, depending on whether inter-site tunneling couplings in the chain are short- or long-range, the existence of environmental interactions, and the temperature of the environment. Our classification and insights of optimal energy landscapes offer guidance for designing efficient transport systems for electronic, photovoltaic and quantum communication applications.