Kondo Effect in a Quantum Dot under Continuous Quantum Measurement

TL;DR

This paper explores how continuous quantum measurement affects the Kondo effect in a quantum dot, revealing suppression of the Kondo resonance and changes in the Kondo temperature due to measurement backaction.

Contribution

It introduces the concept of a generalized Kondo temperature under continuous measurement and analyzes how measurement strength influences the Kondo effect.

Findings

Kondo resonance is suppressed at measurement strengths comparable to the Kondo temperature.

Measurement backaction alters the temperature dependence of spin susceptibility.

A quantitative relationship between measurement strength and generalized Kondo temperature is established.

Abstract

The backaction of quantum measurement on the Kondo effect in a quantum dot system is investigated by considering continuous projective measurement of singly occupied states of a quantum dot. We elucidate the qualitative feature of the Kondo effect under quantum measurement and determine effective Kondo temperature affected by the measurement. The Kondo resonance in the spectral function is suppressed when the measurement strength reaches the energy scale of the Kondo temperature without measurement. Through the spin susceptibility, we identify the generalized Kondo temperature under continuous quantum measurement. The measurement backaction changes the singularity in the spin susceptibility into a highly non-monotonic temperature dependence around the generalized Kondo temperature. The dependence of the generalized Kondo temperature on the measurement strength is quantitatively discussed.