TY - JOUR
T1 - Signatures of incoherence in a quantum information processor
Y1 - 2007
A1 - Michael K. Henry
A1 - Alexey V. Gorshkov
A1 - Yaakov S. Weinstein
A1 - Paola Cappellaro
A1 - Joseph Emerson
A1 - Nicolas Boulant
A1 - Jonathan S. Hodges
A1 - Chandrasekhar Ramanathan
A1 - Timothy F. Havel
A1 - Rudy Martinez
A1 - David G. Cory
AB - Incoherent noise is manifest in measurements of expectation values when the underlying ensemble evolves under a classical distribution of unitary processes. While many incoherent processes appear decoherent, there are important differences. The distribution functions underlying incoherent processes are either static or slowly varying with respect to control operations and so the errors introduced by these distributions are refocusable. The observation and control of incoherence in small Hilbert spaces is well known. Here we explore incoherence during an entangling operation, such as is relevant in quantum information processing. As expected, it is more difficult to separate incoherence and decoherence over such processes. However, by studying the fidelity decay under a cyclic entangling map we are able to identify distinctive experimental signatures of incoherence. This result is demonstrated both through numerical simulations and experimentally in a three qubit nuclear magnetic resonance implementation.
UR - http://arxiv.org/abs/0705.3666v2
ER -