A many-body singlet prepared by a central spin qubit

TL;DR

This paper proposes a protocol using a central spin qubit to generate a many-body singlet state in dense spin ensembles, enabling entanglement engineering and quantum memory applications even with decoherence.

Contribution

It introduces an algorithmic method for preparing a known many-body entangled state using a central spin in dense ensembles, extending quantum state control.

Findings

Protocol feasible across multiple material platforms

Effective even with realistic decoherence levels

Enables creation of collective quantum states

Abstract

Controllable quantum many-body systems are platforms for fundamental investigations into the nature of entanglement and promise to deliver computational speed-up for a broad class of algorithms and simulations. In particular, engineering entanglement within a dense spin ensemble can turn it into a robust quantum memory or a computational platform. Recent experimental progress in dense central spin systems motivates the design of algorithms that use a central-spin qubit as a convenient proxy for the ensemble. Here we propose a protocol that uses a central spin to initialize two dense spin ensembles into a pure anti-polarized state and from there creates a many-body entangled state -- a singlet -- from the combined ensemble. We quantify the protocol performance for multiple material platforms and show that it can be implemented even in the presence of realistic levels of decoherence. Our protocol introduces an algorithmic approach to preparation of a known many-body state and to entanglement engineering in a dense spin ensemble, which can be extended towards a broad class of collective quantum states.