Quantum fluctuations and coherence in high-precision single-electron capture

TL;DR

This paper investigates quantum interference effects in single-electron capture processes, revealing how non-adiabatic dynamics can produce measurable quantum beats that inform the energy scales of dynamic quantum dots.

Contribution

It demonstrates that quantum interference can be harnessed in single-electron sources through non-adiabatic effects, turning errors into diagnostic signals.

Findings

Identification of energy scales in non-adiabatic electron capture

Proposal of a Landau-Zener-backtunneling interferometer

Prediction of quantum beats revealing non-adiabatic dynamics

Abstract

The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the non-adiabatic separation of a localized quantum state from a Fermi sea due to a closing tunnel barrier. We identify the relevant energy scales and suggest ways to separate the contributions of quantum non-adiabatic excitation and backtunneling to the rare non-capture events. In the optimal regime of balanced decay and non-adiabaticity, our simple electron trap turns into a single-lead Landau-Zener-backtunneling interferometer, revealing the dynamical phase accumulated between the particle capture and leakage. The predicted "quantum beats in backtunneling" may turn the error of a single-electron source into a valuable signal revealing essentially non-adiabatic energy scales of a dynamic quantum dot.