Spin-echo dynamics of a heavy hole in a quantum dot

TL;DR

This paper develops a theoretical model for the spin-echo behavior of heavy holes in quantum dots, revealing how magnetic fields and geometry influence decoherence and suggesting strategies for robust hole-spin qubits.

Contribution

It introduces a comprehensive theory accounting for hyperfine and electric-field fluctuations, and identifies conditions to mitigate decoherence in hole-spin qubits.

Findings

Moderate magnetic fields induce motional averaging, reducing hyperfine decoherence.

Spin-echo decay is highly sensitive to the system's geometry.

Specific initialization and pulse axes can reveal intrinsic hyperfine dynamics despite electric dephasing.

Abstract

We develop a theory for the spin-echo dynamics of a heavy hole in a quantum dot, accounting for both hyperfine- and electric-field-induced fluctuations. We show that a moderate applied magnetic field can drive this system to a motional-averaging regime, making the hyperfine interaction ineffective as a decoherence source. Furthermore, we show that decay of the spin-echo envelope is highly sensitive to the geometry. In particular, we find a specific choice of initialization and {\pi}-pulse axes which can be used to study intrinsic hyperfine-induced hole-spin dynamics, even in systems with substantial electric-field-induced dephasing. These results point the way to designed hole-spin qubits as a robust and long-lived alternative to electron spins.