Coherent optical manipulation of quantum dot spins: a path into quantum computing

Abstract

Coherent control of quantum dot qubits transfers optical coherence to electronic coherence and provides a means to demonstrate details of quantum computing including creation/detection of entangled states and qubit rotations. The measurements also provide insight into physical phenomena such as spontaneously generated spin coherence. SummarySemiconductor quantum dots have optical properties similar to simple atomic systems, unlike higher dimensional semiconductor structures that are dominated by manybody physics associated with the continuum states. They also provide a potentially ideal electronic structure appropriate for quantum computing. The data shows that these structures can be coherently controlled on a time scale short compared to the quantum decoherence time and that entangled states of qubits (represented by exciton optical Bloch vectors) can be created. The system is remarkably robust against pure dephasing, and we have been able to demonstrate a simple conditional quantum logic device involving multiple Rabi flops of the exciton and biexciton.