Is Gravity a Quantum Force?
Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics. Along this line, a prime question is to find whether gravity is a quantum entity subject to the rules of quantum mechanics. It is fair to say that there are no feasible ideas yet to test the quantum coherent behaviour of gravity directly in a laboratory experiment. In a recent paper, Gavin Morley and colleagues introduce an idea for such a test based on the principle that two objects cannot be entangled without a quantum mediator. Their paper was published in Physics Review Letters:
and covered in NewScientist:
as well as The Atlantic:
- Caption to figure: A proposed test of the quantum nature of gravity would use two nanodiamonds in free flight. If their spins become entangled then this would be evidence that gravity supports quantum superposition states.
- Publication: S Bose, A Mazumdar, GW Morley, H Ulbricht, M Toroš, M Paternostro, A Geraci, P Barker, MS Kim & G Milburn, A Spin Entanglement Witness for Quantum Gravity, Physical Review Letters 119, 240401 (2017)
- DOI: 10.1103/PhysRevLett.119.240401