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SUMMARY: Decoherence vs diffusion: testing the quantum nature of gravity -
  Jonathan Oppenheim (UCL)
DTSTART:20260129T140000Z
DTEND:20260129T153000Z
UID:TALK242044@talks.cam.ac.uk
CONTACT:Adrian Kent
DESCRIPTION:We consider two interacting systems when one is treated classi
 cally while the other remains quantum. The most general form of such dynam
 ics can be derived and has implications for the foundations of quantum the
 ory\, and to the problem of understanding gravity when spacetime is treate
 d as fundamentally or effectively classically. If any system is treated as
  fundamentally classical\, the dynamics necessarily results in decoherence
  of quantum systems\, and a breakdown in predictability in classical phase
  space. Nonetheless the quantum state remains pure conditioned on the clas
 sical trajectory. We prove that a trade-off between the rate of decoherenc
 e and the degree of diffusion induced in the classical system is a general
  feature of all classical-quantum dynamics. Applying the trade-off to gene
 ral relativity enables us to experimentally test the nature of spacetime. 
 Bounds on decoherence rates arising from interferometry experiments\, comb
 ined with precision acceleration measurements\, squeezes the theory from b
 oth sides and can be used to test whether spacetime has a fundamentally cl
 assical nature.
LOCATION:Center for Mathematical Sciences\, MR2
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