Spin-resolved quantum-dot resonance fluorescence

TL;DR

This paper reports the first observation of spin-selective, near background-free resonance fluorescence from a quantum dot, enabling advanced quantum information processing and new spectroscopic capabilities through the spin-selective dynamic Stark effect.

Contribution

It demonstrates spin-resolved resonance fluorescence and spin-selective Stark tuning in quantum dots, facilitating quantum computing and novel spin system probing.

Findings

Observation of spin-selective, background-free photon emission

Spectral isolation of photons via Mollow triplet in resonance fluorescence

Independent tuning of spin states using the dynamic Stark effect

Abstract

In the quest for physically realizable quantum information science (QIS) primitives, self-assembled quantum dots (QDs) serve a dual role as sources of photonic (flying) qubits and traps for electron spin; the prototypical stationary qubit. Here we demonstrate the first observation of spin-selective, near background-free and transform-limited photon emission from a resonantly driven QD transition. The hallmark of resonance fluorescence, i.e. the Mollow triplet in the scattered photon spectrum when an optical transition is driven resonantly, is presented as a natural way to spectrally isolate the photons of interest from the original driving field. We go on to demonstrate that the relative frequencies of the two spin-tagged photon states are tuned independent of an applied magnetic field via the spin-selective dynamic Stark effect induced by the very same driving laser. This demonstration enables the realization of challenging QIS proposals such as heralded single photon generation for linear optics quantum computing, spin-photon entanglement, and dipolar interaction mediated quantum logic gates. From a spectroscopy perspective, the spin-selective dynamic Stark effect tunes the QD spin-state splitting in the ground and excited states independently, thus enabling previously inaccessible regimes for controlled probing of mesoscopic spin systems.