BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Phase-phenomena in probabilistic theories - Oscar Dahlsten (Univer
 sity of Oxford)
DTSTART:20140529T131500Z
DTEND:20140529T141500Z
UID:TALK52818@talks.cam.ac.uk
CONTACT:William Matthews
DESCRIPTION:Phase plays a crucial role in many quantum effects including i
 nterference. We study phase in probabilistic theories more generally\, in 
 order to gain a deeper understanding of phase in quantum theory as well as
  to consider what could happen in post-quantum scenarios. Phase is normall
 y defined in terms of complex numbers that appear when representing quantu
 m states as complex vectors. Here we give an operational definition whereb
 y phase is instead defined in terms of measurement statistics. The definit
 ion makes it possible to ask whether other (convex) probabilistic theories
  can also have phase and associated phenomena. We use it to explore hypoth
 etical post-quantum particles going through interferometers and find that 
 theories need something like the quantum uncertainty relation between posi
 tion and unbiased measurements in order to have non-trivial interference\,
  or else they would violate a type of Einstein locality which we dub 'Bran
 ch Locality'. We moreover explore the phase that arises from exchanging pa
 rticles in scenarios where particles are guaranteed to be indistinguishabl
 e but not necessarily quantum. We begin to investigate what new types of p
 articles could exist in such scenarios.\n\nBased on:\narXiv:1206.5702\, ar
 Xiv:1304.5977\, arXiv:1307.2529\nJoint work with Garner\, Murao\, Nakata a
 nd Vedral.
LOCATION:MR12\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
END:VEVENT
END:VCALENDAR