Quantum superpositions of crystalline structures

TL;DR

This paper proposes a method to create and detect quantum superpositions of different structural states in ion chains, specifically across the linear-zigzag transition, using spin-dependent forces and Ramsey interferometry.

Contribution

It introduces a novel approach to generate and observe superpositions of motional states in ion chains across structural phase transitions.

Findings

Superpositions of linear and zigzag states can be coherently created.

Entanglement between internal and external degrees of freedom is achievable.

Ramsey interferometry can reveal these superpositions.

Abstract

A procedure is discussed for creating coherent superpositions of motional states of ion strings. The motional states are across the structural transition linear-zigzag, and their coherent superposition is achieved by means of spin-dependent forces, such that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain's internal and external degrees of freedom. It is shown that the creation of such an entangled state can be revealed by performing Ramsey interferometry with one ion of the chain.