Tuning the nuclei-induced spin relaxation of localized electrons by the quantum Zeno and anti-Zeno effects

TL;DR

This paper demonstrates how quantum measurement back action can be used to control spin relaxation in localized electrons, showing suppression via the quantum Zeno effect and acceleration via the anti-Zeno effect in different systems.

Contribution

It provides experimental evidence and a microscopic model for tuning electron spin relaxation using quantum Zeno and anti-Zeno effects.

Findings

Probe pulses suppress spin relaxation in Si donor electrons (Zeno effect).

Increased probe power accelerates spin relaxation in quantum dots (anti-Zeno effect).

Transition between regimes occurs when spin dephasing time matches pulse period.

Abstract

Quantum measurement back action is fundamentally unavoidable when manipulating electron spins. Here we demonstrate that this back action can be efficiently exploited to tune the spin relaxation of localized electrons induced by the hyperfine interaction. In optical pump-probe experiments, powerful probe pulses suppress the spin relaxation of electrons on Si donors in an InGaAs epilayer due to the quantum Zeno effect. By contrast, an increase of the probe power leads to a speed up of the spin relaxation for electrons in InGaAs quantum dots due to the quantum anti-Zeno effect. The microscopic description shows that the transition between the two regimes occurs when the spin dephasing time is comparable to the probe pulse repetition period.