2007/03/20 by Thomas Gorin, Carlos Pineda, Thomas H. Seligman
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.99.240405
published as Phys. Rev. Lett. 99, 240405 (2007) · 4 pages, 2 figures
arxiv created 2007/03/20 · arxiv updated 2009/12/01
We analyze decoherence of a quantum register in the absence of non-local operations i.e. of n non-interacting qubits coupled to an environment. The problem is solved in terms of a sum rule which implies linear scaling in the number of qubits. Each term involves a single qubit and its entanglement with the remaining ones. Two conditions are essential: first decoherence must be small and second the coupling of different qubits must be uncorrelated in the interaction picture. We apply the result to a random matrix model, and illustrate its reach considering a GHZ state coupled to a spin bath.