Switched Control of Electron Nuclear Spin Systems

TL;DR

This paper presents a method for controlling electron-nuclear spin systems at specific magnetic fields by switching the nuclear quantization axis through electron spin flips, enabling universal quantum control.

Contribution

It introduces a novel control scheme that allows universal manipulation of coupled electron-nuclear spins via sequences of electron spin flips and delays.

Findings

Achieves universal control of nuclear spins using electron spin flips.

Enables synthesis of any unitary transformation on the spin system.

Facilitates polarization transfer from electron to nuclear spins.

Abstract

In this article, we study control of electron-nuclear spin dynamics at magnetic field strengths where the Larmor frequency of the nucleus is comparable to the hyperfine coupling strength. The quantization axis for the nuclear spin differs from the static B_0 field direction and depends on the state of the electron spin. The quantization axis can be switched by flipping the state of electron spin, allowing for universal control on nuclear spin states. We show that by performing a sequence of flips (each followed by a suitable delay), we can perform any desired rotation on the nuclear spins, which can also be conditioned on the state of the electron spin. These operations, combined with electron spin rotations can be used to synthesize any unitary transformation on the coupled electron-nuclear spin system. We discuss how these methods can be used for design of experiments for transfer of polarization from the electron to the nuclear spins.