Testing spontaneous wavefunction collapse with quantum electromechanics

TL;DR

This paper proposes a novel experimental approach using superconducting qubits and bulk acoustic wave resonators to detect spontaneous wavefunction collapse, aiming to conclusively test collapse models.

Contribution

It introduces a method combining qubit-resonator coupling and acoustic resonances to enhance collapse signature detection beyond background noise.

Findings

Strong qubit-resonator coupling enables fast measurements.

Bulk acoustic wave resonances amplify collapse-induced heating.

Suppression of quasiparticle heating improves measurement accuracy.

Abstract

Theories of spontaneous wavefunction collapse offer an explanation of the possible breakdown of quantum mechanics for macroscopic systems. However, the challenge of resolving predicted collapse signatures above background noise has precluded conclusive tests. Here, we propose to overcome this challenge using a superconducting qubit to precisely readout the collapse-induced heating of a mechanical resonator. We show that the ability to strongly couple the qubit to the resonator can enable both fast measurements and initialization of the qubit close to its ground state. Combined this greatly suppresses the influence of quasiparticle heating of the qubit, which we predict to be the dominant noise source. We find that bulk acoustic wave resonances can amplify the collapse induced heating due to their ultra-low dissipation. Together, this could enable a conclusive test of collapse models.