Quantum polyspectra for modeling and evaluating quantum transport measurements: A unifying approach to the strong and weak measurement regime

TL;DR

This paper introduces quantum polyspectra up to fourth order as a versatile tool for modeling and analyzing quantum transport measurements, effective in both strong and weak measurement regimes, with applications across various quantum technologies.

Contribution

It presents a unifying framework using quantum polyspectra to analyze quantum transport data, extending analysis capabilities to weak measurement regimes where traditional methods fail.

Findings

Quantum polyspectra can recover tunneling and relaxation rates.

The method is effective in weak measurement regimes.

Features in quantum polyspectra change notably from weak to Zeno regimes.

Abstract

Quantum polyspectra of up to fourth order are introduced for modeling and evaluating quantum transport measurements offering a powerful alternative to methods of the traditional full counting statistics. Experimental time-traces of the occupation dynamics of a single quantum dot are evaluated via simultaneously fitting their 2nd-, 3rd-, and 4th-order spectra. The scheme recovers the same electron tunneling and spin relaxation rates as previously obtained from an analysis of the same data in terms of factorial cumulants of the full counting statistics and waiting-time distributions. Moreover, the evaluation of time-traces via quantum polyspectra is demonstrated to be feasible also in the weak measurement regime even when quantum jumps can no longer be identified from time-traces and methods related to the full counting statistics cease to be applicable. A numerical study of a double dot system shows strongly changing features in the quantum polyspectra for the transition from the weak measurement regime to the Zeno-regime where coherent tunneling dynamics is suppressed. Quantum polyspectra thus constitute a general unifying approach to the strong and weak regime of quantum measurements with possible applications in diverse fields as nano-electronics, circuit quantum electrodynamics, spin noise spectroscopy, or quantum optics.