BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:In the beginning God created tensor\, ... then matter\, ... then s
 peech - Bob Coecke\, Oxford University Computing Laboratory
DTSTART:20110209T141500Z
DTEND:20110209T151500Z
UID:TALK28689@talks.cam.ac.uk
CONTACT:Stephen Clark
DESCRIPTION:This is a tale about quantum computing and a bit of natural la
 nguage\nprocessing\, ... all in pictures!\n\nIt is now exactly 75 years ag
 o that John von Neumann denounced his own\nHilbert space formalism: ``I wo
 uld like to make a confession which may\nseem immoral: I do not believe ab
 solutely in Hilbert space no more.''\n(sic) [1] His reason was that Hilber
 t space does not elucidate in any\ndirect manner the key quantum behaviors
 .  Together with Birkhoff he\ncrafted `quantum logic'\, ... a failed resea
 rch program.\n\nSo what are these key quantum behaviors then?  [2\, 3]  Fo
 r Schrodinger\nthis is the behavior of compound quantum systems\, describe
 d by the tensor\nproduct [4\, again 75 years ago].  While the quantum info
 rmation endeavor\nis to a great extend the result of exploiting this impor
 tant insight\, the\nlanguage of the field is still very much that of strin
 gs of complex\nnumbers\, which is akin to the strings of 0's and 1's in th
 e early days of\ncomputer programming.  If the manner in which we describe
  compound quantum\nsystems captures so much of the essence of quantum theo
 ry\, then it should\nbe at the forefront of the presentation of the theory
 \, and not preceded by\ncontinuum structure\, field of complex numbers\, v
 ector space over the\nlatter\, etc\, to only then pop up as some secondary
  construct.\n\nOver the past couple of years we have played the following 
 game: how much\nquantum phenomena can be derived from `compoundness + epsi
 lon'. It turned\nout that epsilon can be taken to be `very little'\, surel
 y not involving\nanything like continuum\, fields\, vector spaces\, but me
 rely a\n`two-dimensional space' of temporal composition (cf `and then') an
 d\ncompoundness (cf `while')\, together with some very natural purely\nope
 rational assertion\, including one which in a constructive manner\nasserts
  entanglement\; among many other things\, trace structure (cf von\nNeumann
  above) then follow [5\, survey].  This `categorical quantum\nmechanics' r
 esearch program started with [6].\n\nIn a very short time\, this radically
  different approach has produced a\nuniversal graphical language for quant
 um theory which helped to resolve\nsome open problems [7\,8\,9]\, in quant
 um foundations\, measurement based\nquantum computing\, and on the structu
 re of multi-partite entanglement. It\ngives a particularly elegant account
  on complementarity and the quantum\nclassical interaction [10\, 11]. It a
 lso paved the way to automate quantum\nreasoning\, by means of the Quantom
 atic software [12].\n\nThe approach has even helped to solve problems outs
 ide physics\, most\nnotably in modeling meaning for natural languages whic
 h was the  first\nelegant mathematical solution to this problem [13\, 14].
   Both the\nautomation and the support of structures in natural language j
 ustifies the\nlabel of "Logic" (as opposed to Birkhoff and von Neumann's q
 uantum logic).\n\n[1] M Redei (1997) Why John von Neumann did not like the
  Hilbert space\nformalism of quantum mechanics (and what he liked instead)
 .  Stud Hist\nPhil Mod Phys 27\, 493-510.\n\n[2] For von Neumann\, initial
 ly these were the propositions that one could\nmeasure with certainty\, an
  idea that he later abandoned in favor of the\ntrace structure\, which gen
 erates probability [1].\n\n[3] Still\, today for most physicists `quantum'
  is synonym for `Hilbert\nspace'\, which of course is not unrelated to the
  dominant ``shut up and\ncalculate''-interpretation of quantum theory.\n\n
 [4] E Schroedinger\, (1935) Discussion of probability relations between\ns
 eparated systems.  Proc Camb Phil Soc 31\, 555-563\; (1936) 32\, 446-451.\
 n\n[5] B Coecke (2010) Quantum picturalism. Cont Phys 51\, 59-83.\narXiv:0
 908.1787\n\n[6] S Abramsky & B Coecke (2004) A categorical semantics of qu
 antum\nprotocols. LiCS '04. arXiv:0808.1023\n\n[7] B Coecke\, B Edwards an
 d RW Spekkens (2010) Phase groups and the origin\nof non-locality for qubi
 ts.  ENTCS\, to appear. arXiv:1003.5005\n\n[8] R Duncan and S Perdrix (201
 0) Rewriting measurement-based quantum\ncomputations with generalised flow
 . ICALP'10.\n\n[9] B Coecke and A Kissinger (2010) The compositional struc
 ture of\nmultipartite quantum entanglement. ICALP'10. arXiv:1002.2540\n\n[
 10] B Coecke and R Duncan (2008) Interacting quantum observables.\nICALP'0
 8. arXiv:0906.4725\n\n[11] B Coecke and S Perdrix (2010) Environment and c
 lassical channels in\ncategorical quantum mechanics. CSL'10. arXiv:1004.15
 98\n\n[12] L Dixon\, R Duncan & A Kissinger.\ndream.inf.ed.ac.uk/projects/
 quantomatic/\n\n[13] B Coecke\, S Clark & M Sadrzadeh (2010) Ling Anal 36.
  Mathematical\nfoundations for a compositional distributional model of mea
 ning.\narXiv:1003.4394\n\n[14] New Scientist: Quantum links let computers 
 understand language\, 8\nDecember 2010.\n\n
LOCATION:Lecture Theatre 1\, Computer Laboratory
END:VEVENT
END:VCALENDAR