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Zenith Grant Awardee

George Andrew David Briggs

University of Oxford


Gerard James Milburn, University of Queensland; Edward Laird, University of Oxford; Natalia Ares, University of Oxford

Project Title

Bench-top experimental test of gravitation as an observer of quantum states

Project Summary

Despite the remarkable success of quantum mechanics, problems arise when extending quantum principles to larger objects. This problem is encapsulated in one of the most famous thought experiments in science: the Schr\\\"{o}dinger\'s Cat scenario. An undoubtedly quantum event, the decay of a nucleus, is mapped to a macroscopic event, i.e. the death of the cat, but only when there is an observer. Until then, is there anything to stop the cat from being simultaneously dead and alive? As quantum states are known to be perturbed and ultimately, destroyed by the presence of an observer, a question arises: `What kind of non-human observer might prevent dead-and-alive cats?\'. A good place to look for the answer to that question is in the experimentally unexplored territory where quantum mechanics has to be reconciled with gravitation. Gravitational effects in quantum systems are typically small, making bench-top experiments extremely challenging. Advances in nanotechnology and cryogenic engineering are beginning to bring such experiments within reach. We propose to evaluate the feasibility of a bench-top (or rather cryostat-bottom) experiment based on two nanomechanical oscillators to explore the effect of gravity as an observer, responsible for the emergence of a classical world.

Technical Abstract

Gravitational interactions in quantum systems could be at the heart of the emergence of the classical world. As the effect of gravity in systems that exhibit quantum behaviour is very small, gravitational decoherence might not be expected to arise in laboratory-scale experiments. The fast-paced development of nano and micro-mechanical resonators could overturn such preconceptions. We propose to evaluate the feasibility of a bench-top test of gravitational decoherence based on an optomechanical setup composed of two mechanical oscillators. The sensitivity to heating effects, a signature of gravitational decoherence, will be explored by the realization of optomechanic experiments and detailed calculations.

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