Spin entanglement witness for quantum gravity

Bose, S., Mazumdar, A., Morley, G., Ulbricht, H., Toros, M. , Paternostro, M., Geraci, A., Barker, P., Kim, M. S. and Milburn, G. (2017) Spin entanglement witness for quantum gravity. Physical Review Letters, 119, 240401. (doi: 10.1103/PhysRevLett.119.240401)

Abstract

Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics. However, the lack of empirical evidence has lead to a debate on whether gravity is a quantum entity. Despite varied proposed probes for quantum gravity, it is fair to say that there are no feasible ideas yet to test its quantum coherent behavior directly in a laboratory experiment. Here, we introduce an idea for such a test based on the principle that two objects cannot be entangled without a quantum mediator. We show that despite the weakness of gravity, the phase evolution induced by the gravitational interaction of two micron size test masses in adjacent matter-wave interferometers can detectably entangle them even when they are placed far apart enough to keep Casimir-Polder forces at bay. We provide a prescription for witnessing this entanglement, which certifies gravity as a quantum coherent mediator, through simple spin correlation measurements.

• Item Type: Articles
• Additional Information: H. U. and M. T. acknowledge funding by the Leverhulme Trust (Grant No. RPG-2016-046) and the Foundational Questions Institute (FQXi). A. G. is supported by the U.S. National Science Foundation (Grant No. PHY-1506431). M. S. K. acknowledges a Leverhulme Trust Research Grant (Grant No. RPG2014-055), the Royal Society, and an EPSRC grant (Grant No. EP/K034480/1). M. P. acknowledges support from the EU Collaborative Project TherMiQ (Grant No. 618074), the SFI-DfE Investigator Program (Grant No. 15/IA/2864), the Royal Society, and the COST Action CA15220 Quantum Technologies in Space. G. W. M. is supported by the Royal Society and the United Kingdom EPSRC Networked Quantum Information Technology Hub (Grant No. EP/M013243/1). P. B. and S. B. acknowledge EPSRC Grant No. EP/N031105/1. S. B. acknowledges ERC Grant No. 308253 PACOMANEDIA and EPSRC Grant No. EP/K004077/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Toros, Dr Marko
• Authors: Bose, S., Mazumdar, A., Morley, G., Ulbricht, H., Toros, M., Paternostro, M., Geraci, A., Barker, P., Kim, M. S., and Milburn, G.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review Letters
• Publisher: American Physical Society
• ISSN: 0031-9007
• ISSN (Online): 1079-7114
• Copyright Holders: Copyright © 2017 American Physical Society
• First Published: First published in Physical Review Letters 119:240401
• Publisher Policy: Reproduced in accordance with the publisher copyright policy