Dissipation in a quantum wire: fact and fantasy

TL;DR

This paper investigates the fundamental question of where and how energy dissipation occurs in quantum wires, emphasizing the role of inelastic scattering at interfaces and connecting theory with experimental observations.

Contribution

It revisits the quantum kinetic basis of dissipation, providing a definitive explanation and linking dissipation signatures to measurable current noise in quantum point contacts.

Findings

Dissipation manifests in non-equilibrium current noise.

Experimental signatures of dissipation have been observed.

Dissipation occurs mainly at interfaces and leads, not in the ballistic channel itself.

Abstract

Where, and how, does energy dissipation of electrical energy take place in a ballistic wire? Fully two decades after the advent of the transmissive phenomenology of electrical conductance, this deceptively simple query remains unanswered. We revisit the quantum kinetic basis of dissipation and show its power to give a definitive answer to our query. Dissipation leaves a clear, quantitative trace in the non-equilibrium current noise of a quantum point contact; this signature has already been observed in the laboratory. We then highlight the current state of accepted understandings in the light of well-known yet seemingly contradictory measurements. The physics of mesoscopic transport rests not in coherent carrier transmission through a perfect and dissipationless metallic channel, but explicitly in their dissipative inelastic scattering at the wire's interfaces and adjacent macroscopic leads.