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SUMMARY:A variational eigenvalue solver on a quantum processor - McClean\,
  J (Harvard University)
DTSTART:20131128T100000Z
DTEND:20131128T110000Z
UID:TALK49084@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Co-authors: Alberto Peruzzo (University of Sydney)\, Peter Sha
 dbolt (University of Bristol)\, Man-Hong Yung (Tsinghua University)\, Xiao
 -Qi Zhou (University of Bristol)\, Peter Love (Haverford College)\, Alan A
 spuru-Guzik (Harvard University)\, Jeremy O'Brien (University of Bristol) 
 \n\nQuantum computers promise to efficiently solve important problems that
  are intractable on a conventional computer. For quantum systems\, where t
 he dimension of the problem space grows exponentially\, finding the eigenv
 alues of certain operators is one such intractable problem and remains a f
 undamental challenge. The quantum phase estimation algorithm can efficient
 ly find the eigenvalue of a given eigenvector but requires fully coherent 
 evolution. We present an alternative approach that greatly reduces the req
 uirements for coherent evolution and we combine this method with a new app
 roach to state preparation based on ans"atze and classical optimization. W
 e have implemented the algorithm by combining a small-scale photonic quant
 um processor with a conventional computer. We experimentally demonstrate t
 he feasibility of this approach with an example from quantum chemistry: ca
 lculating the ground state molecular energy for He-H+\, to within chemical
  accuracy. The proposed appro ach\, by drastically reducing the coherence 
 time requirements\, enhances the potential of the quantum resources availa
 ble today and in the near future.\n
LOCATION:Seminar Room 1\, Newton Institute
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