title: Quantum-dot-spin single-photon interface.
abstract: Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0.1%, we realize a classical single spin-photon interface where the detection of a scattered photon with 300 ps time resolution projects the quantum dot spin to a definite spin eigenstate with fidelity exceeding 99%. The bunching of resonantly scattered photons reveals information about electron spin dynamics. High-fidelity fast spin-state initialization heralded by a single photon enables the realization of quantum information processing tasks such as nondeterministic distant spin entanglement. Given that we could suppress the measurement backaction to well below the natural spin-flip rate, realization of a quantum nondemolition measurement of a single spin could be achieved by increasing the fluorescence collection efficiency by a factor exceeding 10 using a photonic nanostructure.
authors.affiliation: Institute of Quantum Electronics, ETH Zurich, CH-8093 Zu¨rich, Switzerland.
authors.forename: S T
authors.initials: ST
authors.lastname: Yilmaz
authors.forename: P
authors.initials: P
authors.lastname: Fallahi
authors.forename: A
authors.initials: A
authors.lastname: Imamoğlu