《Role of single-qubit decoherence time》.pdf

PHYSICAL REVIEW A 80, 022303 2009 Role of single-qubit decoherence time in adiabatic quantum computation 1 1 2 M. H. S. Amin, C. J. S. Truncik, and D. V. Averin 1 D-Wave Systems Inc., 100-4401 Still Creek Drive, Burnaby, British Columbia, Canada V5C 6G9 2 Department of Physics and Astronomy, SUNY Stony Brook, Stony Brook, New York 11794, USA Received 2 May 2008; revised manuscript received 16 December 2008; published 4 August 2009 We have studied numerically the evolution of an adiabatic quantum computer in the presence of a Markov- ian Ohmic environment by considering Ising spin-glass systems with up to 20 qubits independently coupled to this environment via two conjugate degrees of freedom. The required computation time is demonstrated to be of the same order as that for an isolated system and is not limited by the single-qubit decoherence time T2, even when the minimum gap is much smaller than the temperature and decoherence-induced level broadening. For small minimum gap, the system can be described by an effective two-state model coupled only longitudinally to environment. DOI: 10.1103/PhysRevA.80.022303 PACS numbers: 03.67.Lx, 03.65.Yz Adiabatic quantum computation 1 AQC is an attrac- ence. Qualitatively, one expects decoherence to drive the sys- tive model of quantum computation QC. It