Coherence of spin qubits in silicon

Abstract

Given the effectiveness of semiconductor devices for classical computation one is naturallyled to consider semiconductor systems for solid state quantum information processing.Semiconductors are particularly suitable where local control of electric fields and chargetransport are required. Conventional semiconductor electronics is built upon thesecapabilities and has demonstrated scaling to large complicated arrays of interconnecteddevices. However, the requirements for a quantum computer are very different from thosefor classical computation, and it is not immediately obvious how best to build one ina semiconductor. One possible approach is to use spins as qubits: of nuclei, ofelectrons, or both in combination. Long qubit coherence times are a prerequisite forquantum computing, and in this paper we will discuss measurements of spincoherence in silicon. The results are encouraging—both electrons bound to donors andthe donor nuclei exhibit low decoherence under the right circumstances. Dopedsilicon thus appears to pass the first test on the road to a quantum computer.