Displacemon electromechanics: how to detect quantum interference in a nanomechanical resonator

TL;DR

This paper proposes a novel electromechanical system called 'displacemon' that enables the generation and detection of quantum interference in a nanomechanical resonator, advancing quantum control of macroscopic objects.

Contribution

It introduces the displacemon architecture and a protocol for creating and measuring quantum superpositions in nanomechanical systems, demonstrating feasibility with realistic parameters.

Findings

Protocol can generate superpositions with over 10^6 nucleons.

Simulation shows strong coupling enables quantum interference detection.

Feasibility demonstrated with carbon nanotube-based system.

Abstract

We introduce the `displacemon' electromechanical architecture that comprises a vibrating nanobeam, e.g. a carbon nanotube, flux coupled to a superconducting qubit. This platform can achieve strong and even ultrastrong coupling enabling a variety of quantum protocols. We use this system to describe a protocol for generating and measuring quantum interference between two trajectories of a nanomechanical resonator. The scheme uses a sequence of qubit manipulations and measurements to cool the resonator, apply an effective diffraction grating, and measure the resulting interference pattern. We simulate the protocol for a realistic system consisting of a vibrating carbon nanotube acting as a junction in a superconducting qubit, and we demonstrate the feasibility of generating a spatially distinct quantum superposition state of motion containing more than $10^6$ nucleons.