Universal quantum computing with correlated spin-charge states

Abstract

We propose a universal quantum computing scheme in which the orthogonal qubit states |0i and |1> are identical in their single-particle spin and charge properties. Each qubit is contained in a single quantum dot and gate operations are induced all-electrically by changes in the confinement potential. Within the computational space, these qubits are robust against environmental influences that couple to the system through single-particle channels. Due to the identical spin and charge properties of the |0>, |1> states, the lowest-order relaxation and decoherence rates 1/T1 and 1/T2, within the Born-Markov approximation, both vanish for a large class of environmental couplings. We give explicit pulse sequences for a universal set of gates (phase, phi/8, Hadamard, cnot) and discuss state preparation, manipulation, and detection.