Reducing pure dephasing of quantum bits by collective encoding in quantum dot arrays

Abstract

We show that phonon-induced pure dephasing of an excitonic (charge) quantum bit in a quantum dot (QD) may be reduced by collective encoding of logical qubits in QD arrays. We define the logical qubit on an array of 2, 4 and 8 QDs, connecting the logical |0〉 state with the presence of excitons in the appropriately chosen half of dots and the logical |1〉 state with the other half of the dots occupied. We give quantitative estimates of the resulting total error of a single qubit operation for an InAs/GaAs system. © 2006 IOP Publishing Ltd.