| dc.contributor | Gorin, T., Departamento de F�sica, Universidad de Guadalajara, Guadalajara, Mexico; Pineda, C., Centro Internacional de Ciencias, Cuernavaca, Mexico, Instituto de Ciencias F�sicas, Universidad Nacional Aut�noma de M�xico, Cuernavaca, Mexico, Instituto de F�sica, Universidad Nacional Aut�noma de M�xico, M�xico D. F., Mexico; Seligman, T.H., Centro Internacional de Ciencias, Cuernavaca, Mexico, Instituto de Ciencias F�sicas, Universidad Nacional Aut�noma de M�xico, Cuernavaca, Mexico | |
| dc.description.abstract | We analyze decoherence of a quantum register in the absence of nonlocal operations, i.e., n noninteracting 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 Greenberger-Horne-Zeilinger state coupled to a spin bath. � 2007 The American Physical Society. | |
