Full coherent control of nuclear spins in an optically pumped single quantum dot

TL;DR

This paper demonstrates rapid, coherent control of nuclear spins in a quantum dot using RF pulses, enabling dynamic manipulation of Overhauser fields for advanced quantum information applications.

Contribution

It introduces a method for fast, coherent redirection of nuclear spins in a quantum dot, surpassing previous static control limitations.

Findings

Achieved microsecond-scale control of Overhauser fields up to 0.5 T.

Controlled an ensemble of 10^3-10^4 nuclear spins using RF pulse sequences.

Opened pathways for advanced nuclear spin experiments like spin squeezing.

Abstract

Highly polarized nuclear spins within a semiconductor quantum dot (QD) induce effective magnetic (Overhauser) fields of up to several Tesla acting on the electron spin or up to a few hundred mT for the hole spin. Recently this has been recognized as a resource for intrinsic control of QD-based spin quantum bits. However, only static long-lived Overhauser fields could be used. Here we demonstrate fast redirection on the microsecond time-scale of Overhauser fields of the order of 0.5 T experienced by a single electron spin in an optically pumped GaAs quantum dot. This has been achieved using full coherent control of an ensemble of 10^3-10^4 optically polarized nuclear spins by sequences of short radio-frequency (rf) pulses. These results open the way to a new class of experiments using rf techniques to achieve highly-correlated nuclear spins in quantum dots, such as adiabatic demagnetization in the rotating frame leading to sub-micro K nuclear spin temperatures, rapid adiabatic passage, and spin squeezing.