Quantum Parallelism as a Tool for Ensemble Spin Dynamics Calculations

GONZALO A. ÁLVAREZ; ERNESTO P. DANIELI; PATRICIA R. LEVSTEIN; HORACIO M. PASTAWSKI

PHYSICAL REVIEW LETTERS

American Physical Society

Año: 2008 vol. 101 p. 120503 - 120503

0031-9007

Gonzalo A. Álvarez, Ernesto P. Danieli, Patricia R. Levstein, and Horacio M. Pastawski Efficient simulations of quantum evolutions of spin-1/2 systems are relevant for ensemble quantum computation as well as in typical NMR experiments. We propose an efficient method to calculate the dynamics of an observable provided that the initial excitation is “local.” It resorts to a single entangled pure initial state built as a superposition, with random phases, of the pure elements that compose the mixture. This ensures self-averaging of any observable, drastically reducing the calculation time. The procedure is tested for two representative systems: a spin star (cluster with random long range interactions) and a spin ladder. Phys. Rev. Lett. 101, 120503 (2008)