From Dirac to Diffusion: Decoherence in Quantum Lattice Gases

  • Authors:
  • Peter J. Love;Bruce M. Boghosian

  • Affiliations:
  • Aff1 Aff2;Department of Mathematics, Tufts University, Medford, USA 02155

  • Venue:
  • Quantum Information Processing
  • Year:
  • 2005

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Abstract

We describe a model for the interaction of the internal (spin) degree of freedom of a quantum lattice-gas particle with an environmental bath. We impose the constraints that the particle-bath interaction be fixed, while the state of the bath is random, and that the effect of the particle-bath interaction be parity invariant. The condition of parity invariance defines a subgroup of the unitary group of actions on the spin degree of freedom and the bath. We derive a general constraint on the Lie algebra of the unitary group which defines this subgroup, and hence guarantees parity invariance of the particle-bath interaction. We show that generalizing the quantum lattice gas in this way produces a model having both classical and quantum discrete random walks as different limits. We present preliminary simulation results illustrating the intermediate behavior in the presence of weak quantum noise