Macroscopic non-classical state preparation via post-selection

TL;DR

This paper proposes a probabilistic, post-selection-based method to generate macroscopic quantum states like qubits, Schrödinger's cats, and Fock states in mechanical systems without external driving.

Contribution

It introduces a novel scheme utilizing spin post-selection in weak coupling regimes to produce macroscopic quantum superpositions on demand.

Findings

Successful generation of mechanical qubits, Schrödinger's cat, and Fock states.

Superpositions are linked to amplified mechanical quadrature mean values.

The scheme operates without external driving, relying solely on spin post-selection.

Abstract

Macroscopic mechanical qubits are fundamental both to test the classical-quantum boundary and present suitable candidates for quantum information processing. Motivated by these, we propose a feasible probabilistic scheme to generate an on-demand mechanical qubit, as well as Schr\"{o}dinger's cat and Fock number states. In order to accomplish this proposal, we study an open dispersive spin-mechanical system in the absence of any external driving. The procedure is solely based on spin post-selection in the weak coupling regime. Through this scheme we demonstrate that the achieved superposition is closely related to the amplification of the mean values of the mechanical quadratures as they are associated to the maximum quantum coherence.