Nuclear spin state narrowing via gate--controlled Rabi oscillations in a double quantum dot

TL;DR

This paper demonstrates how gate-controlled Rabi oscillations in a double quantum dot can be used to narrow nuclear spin states, thereby enhancing electron spin coherence times for quantum computing applications.

Contribution

It introduces a method to control nuclear spin states via oscillating exchange interaction, improving coherence in double quantum dot spin qubits.

Findings

Rabi resonance width scales with oscillating exchange amplitude

Narrowing nuclear spin distribution prolongs spin decoherence time

System parameters can be optimized for high-fidelity quantum operations

Abstract

We study spin dynamics for two electrons confined to a double quantum dot under the influence of an oscillating exchange interaction. This leads to driven Rabi oscillations between the $\ket{\uparrow\downarrow}$--state and the $\ket{\downarrow\uparrow}$--state of the two--electron system. The width of the Rabi resonance is proportional to the amplitude of the oscillating exchange. A measurement of the Rabi resonance allows one to narrow the distribution of nuclear spin states and thereby to prolong the spin decoherence time. Further, we study decoherence of the two-electron states due to the hyperfine interaction and give requirements on the parameters of the system in order to initialize in the $\ket{\uparrow\downarrow}$--state and to perform a $\sqrt{\mathrm{SWAP}}$ operation with unit fidelity.