Schrodinger cat states of a mechanical resonator in two papers

Short answer: Quantum theory allows a system to be in a superposition at any size, yet we never see macroscopic objects in one. Two papers from the same line of work report a mechanical resonator with an effective mass of about 16 micrograms prepared in Schrodinger cat states of motion, and then use its decoherence to test one gravity-related collapse model. These are laboratory experiments, one published and one a preprint.

Why put a mechanical object in a cat state?

The 2022 arXiv abstract frames the problem. According to the Schrodinger equation, a physical system can be in any linear combination of its possible states. This superposition principle is routinely validated for microscopic systems, but the authors say it remains unclear why macroscopic objects are not observed in superpositions of states that can be distinguished by some classical property. A mechanical resonator is a natural test object because its motion can be controlled and measured.

What did the 2022 experiment prepare?

The authors demonstrate the preparation of a mechanical resonator with an effective mass of 16.2 micrograms in Schrodinger cat states of motion, where the constituent atoms are in a superposition of oscillating with two opposite phases. They show control over the size and phase of the superposition and investigate the decoherence dynamics of these states. The arXiv record links this work to a Science publication. They say that apart from probing the boundary between the quantum and classical worlds, the results are of interest for quantum technologies, as they pave the way towards continuous-variable quantum information processing and quantum metrology with mechanical resonators. That is a stated prospect.

What did the 2023 preprint test?

The 2023 preprint, which may not have been peer reviewed, starts from the idea that modifications to quantum theory could cause an objective collapse of the wave function above a critical mass, restoring classical behaviour at the macroscopic scale. One possibility the authors mention is that such modifications relate to gravity, as in the Diosi-Penrose wavefunction collapse model. They investigate this model using experimental measurements of the decoherence of a Schrodinger cat state of a mechanical resonator with an effective mass of 16 micrograms. The abstract available to us does not state the outcome, so no result is claimed here.

What about the news item?

A Physics Today news article on a macroscopic mechanical oscillator being herded into a cat state was on the source list. Its text was not read for this post, so nothing is taken from it.

How to read this

Cat state here means a superposition of two distinct motional states, and 16 micrograms is an effective mass of the oscillating mode as defined by the authors. It is large for a quantum experiment and tiny in everyday terms. The two papers are linked, so they do not count as independent confirmations. This post is based on abstracts, and full texts were not checked. It makes no claim about products or about the validity of any collapse model.

FAQ

What is a Schrodinger cat state of a resonator?

A superposition in which the resonator's atoms oscillate with two opposite phases, per the 2022 abstract.

How massive was the resonator?

An effective mass of 16.2 micrograms in the 2022 paper.

What is the Diosi-Penrose model?

A proposed objective collapse model related to gravity, which the 2023 preprint investigates.

Did the experiment rule it out?

The abstract does not say, so this post makes no such claim.