Decoherence and gate performance of coupled solid state qubits

Markus J. Storcz; Frank K. Wilhelm

doi:10.1103/PhysRevA.67.042319

paper

Decoherence and gate performance of coupled solid state qubits

arXiv:cond-mat/0212374 · doi:10.1103/PhysRevA.67.042319

Abstract

Solid state quantum bits are promising candidates for the realization of a {\em scalable} quantum computer. However, they are usually strongly limited by decoherence due to the many extra degrees of freedom of a solid state system. We investigate a system of two solid state qubits that are coupled via $σ_{z}^{(i)} \otimes σ_{z}^{(j)}$ type of coupling. This kind of setup is typical for {\em pseudospin} solid-state quantum bits such as charge or flux systems. We evaluate decoherence properties and gate quality factors in the presence of a common and two uncorrelated baths coupling to $σ_{z}$ , respectively. We show that at low temperatures, uncorrelated baths do degrade the gate quality more severely. In particular, we show that in the case of a common bath, optimum gate performance of a CPHASE gate can be reached at very low temperatures, because our type of coupling commutes with the coupling to the decoherence, which makes this type of coupling attractive as compared to previously studied proposals with $σ_{y}^{(i)} \otimes σ_{y}^{(j)}$ -coupling. Although less pronounced, this advantage also applies to the CNOT gate.

15 pages, 16 figures, 1 table, submitted to Phys. Rev. A

Decoherence and gate performance of coupled solid state qubits

Abstract

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