Non-locally entangled microwave and micromechanical squeezed cats: a phase transition-based protocol

TL;DR

This paper proposes a protocol using quantum phase transitions in superconducting electromechanical arrays to generate and observe entangled, squeezed, and Schrödinger cat states across multiple microwave and micromechanical modes.

Contribution

It introduces a novel method leveraging quantum phase transitions to produce complex non-classical states in many-body electromechanical systems.

Findings

Demonstrates feasibility with existing superconducting technology

Shows simultaneous generation of entanglement, squeezing, and cat states

Extends quantum state engineering to many-body electromechanical systems

Abstract

Electromechanical systems currently offer a path to engineering quantum states of microwave and micromechanical modes that are of both fundamental and applied interest. Particularly desirable, but not yet observed, are mechanical states that exhibit entanglement, wherein non-classical correlations exist between distinct modes; squeezing, wherein the quantum uncertainty of an observable quantity is reduced below the standard quantum limit; and Schr\"odinger cats, wherein a single mode is cast in a quantum superposition of macroscopically distinct classical states. Also, while most investigations of electromechanical systems have focussed on single- or few-body scenarios, the many-body regime remains virtually unexplored. In such a regime quantum phase transitions naturally present themselves as a resource for quantum state generation, thereby providing a route toward entangling a large number of electromechanical systems in highly non-classical states. Here we show how to use existing superconducting circuit technology to implement a (quasi) quantum phase transition in an array of electromechanical systems such that entanglement, squeezing, and Schr\"odinger cats become simultaneously observable across multiple microwave and micromechanical oscillators.