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SUMMARY: Monogamy\, entanglement and deep hidden variables - Dr Michael Se
 evinck (Utrecht)
DTSTART:20090212T140000Z
DTEND:20090212T150000Z
UID:TALK17042@talks.cam.ac.uk
CONTACT:Berry Groisman
DESCRIPTION:Despite over 40 years of research on Bell-type inequalities\, 
 the\nquestion of non-locality and entanglement\, new technical results tha
 t have\ngeneral foundational relevance can still be obtained. In this talk
  I will\npresent a number of new results that deal with the question of ho
 w to\ndiscern local\, quantum and no-signaling correlations.\n\nI will fir
 st introduce some technical results that deal with novel quantum\ninequali
 ties that strengthen the Tsirelson inequalities and non-trivial\nno-signal
 ing inequalities that discern no-signaling correlations from\ngeneral corr
 elations. The latter have striking similarity with the\nwell-known CHSH in
 equality\, yet they are crucially different.\n\nNext I will show interesti
 ng relationships that exist between inferences on\nthe surface and subsurf
 ace level of a hidden variable theory. Here the\nsurface level deals with 
 experimentally accessible probabilities (e.g.\, via\nrelative frequencies)
  and the sub-surface level deals with probabilities\nthat are conditioned 
 on a hidden-variable (or the quantum state). The most\ninteresting such a 
 relationship is the following: any deterministic\nhidden-variable theory t
 hat obeys no- signaling and gives non-local\ncorrelations must show random
 ness at the surface\, i.e.\, the surface\nprobabilities cannot be determin
 istic. This is the case in Bohmian mechanics\nbut this result shows it to 
 be generic.\n\nLastly\, I intend to discuss monogamy and its relevance to 
 foundations of\nquantum mechanics. It has been known for a while that enta
 nglement is\nmonogamous\, i.e.\, it can not be shared freely. I will exten
 d the discussion\nto the shareability and monogamy aspects\, not just of e
 ntanglement\, but also\nof correlations. It turns out that certain non-loc
 al quantum correlations\ncannot be freely shared\, i.e. they are monogamou
 s as well. This raises the\nquestion of how shareability (monogamy) of non
 -local correlations and\nshareability (monogamy) of quantum entanglement a
 re related. I will show\nthat they are related in a non-trivial\, subtle w
 ay. This allows for a new -\nand hopefully illuminating- interpretation of
  the Bell theorem. This\ndiscussion will be extended from quantum correlat
 ions to monogamy aspects of\nmore general correlations such as no-signalin
 g and partially local\ncorrelations.\n\nThroughout the talk I will show ho
 w these topics are related\,\nand comment on the foundational impact of th
 e results obtained. 
LOCATION:Center for Mathematical Sciences\, Lecture room MR11
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