Generating Entanglement and Squeezed States of Nuclear Spins in Quantum Dots

TL;DR

This paper proposes a novel method to generate and detect entanglement and squeezed states of nuclear spins in quantum dots by using electron spin resonance to induce non-linear twisting dynamics, enabling quantum control of nuclear spin states.

Contribution

It introduces a new scheme for coherent spin squeezing in nuclear spins within quantum dots, differing from previous classical polarization narrowing methods.

Findings

Demonstrates a non-linear twisting mechanism for nuclear spin squeezing

Achieves coherent control of nuclear spin states in quantum dots

Provides a pathway for quantum information processing with nuclear spins

Abstract

Entanglement generation and detection are two of the most sought-after goals in the field of quantum control. Besides offering a means to probe some of the most peculiar and fundamental aspects of quantum mechanics, entanglement in many-body systems can be used as a tool to reduce fluctuations below the standard quantum limit. For spins, or spin-like systems, such a reduction of fluctuations can be realized with so-called squeezed states. Here we present a scheme for achieving coherent spin squeezing of nuclear spin states in few-electron quantum dots. This work represents a major shift from earlier studies in quantum dots, which have explored classical "narrowing" of the nuclear polarization distribution through feedback involving stochastic spin flips. In contrast, we use the nuclear-polarization-dependence of the electron spin resonance (ESR) to provide a non-linearity which generates a non-trivial, area-preserving, "twisting" dynamics that squeezes and stretches the nuclear spin Wigner distribution without the need for nuclear spin flips.