Quantum or Classical Gravity?

Illustration of the proposal for a tabletop test of QG

An international team led by the University of Nottingham, has demonstrated that only quantum and not classical gravity could be used to create a certain informatic ingredient that is needed for quantum computation.

This new research, which is a collaboration between experts in quantum computing, quantum gravity, and quantum experiments finds an unexpected connection between the fields of quantum computing and quantum gravity and uses this to propose a way to test experimentally that there is quantum not classical gravity.

The suggested experiment would involve cooling billions of atoms in a millimeter-sized spherical trap to extremely low temperatures such that they enter a new phase of matter, called a Bose-Einstein condensate, and start to behave like a single large, quantum atom. A magnetic field is then applied to this “atom” so that it feels only its own gravitational pull. With this all in place, if the single gravitating atom demonstrates the key ingredient needed for quantum computation, which is curiously associated with “negative probability,” nature must take the quantum gravity approach.

This proposed experiment uses current technology, involves just a single quantum system, the gravitating “atom,” and does not rely on assumptions concerning the locality of the interaction, making it simpler than previous approaches and potentially expediating the delivery of the first experimental test of quantum gravity.

Physicists would then, after more than a hundred years of research, finally have information on the true overarching, fundamental theory of nature. (Phys.org)

Their research has been published in PRX Quantum.

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