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arXiv · 2407.18876

Fast optical control of a coherent hole spin in a microcavity

Mark Hogg·Nadia Antoniadis·Malwina Marczak·Giang Nguyen·Timon Baltisberger·Alisa Javadi·Ruediger Schott·Sascha Valentin·Andreas Wieck·Arne Ludwig·Richard Warburton
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Abstract

A spin-photon interface is one of the key components of a quantum network. Physical platforms under investigation span the range of modern experimental physics, from ultra-cold atoms and ions to a variety of solid-state systems. Each system has its strengths and weaknesses, typically with a trade-off between spin properties and photonic properties. Currently, the best deterministic single-photon sources use a semiconductor quantum dot embedded in an optical microcavity. However, coherent spin control has not yet been integrated with a state-of-the-art single-photon source, and the magnetic noise from host nuclear spins in the semiconductor environment has placed strong limitations on the spin coherence. Here, we combine high-fidelity all-optical spin control with a quantum dot in an open microcavity, currently the most efficient single-photon source platform available. By imprinting a microwave signal onto a red-detuned optical field, a Raman process, we demonstrate coherent rotations of a hole spin around an arbitrary axis of the Bloch sphere, achieving a maximum {\pi}-pulse fidelity of 98.6%. The cavity enhances the Raman process, enabling ultra-fast Rabi frequencies above 1 GHz. We use our flexible spin control to perform optical cooling of the nuclear spins in the host material via the central hole spin, extending the hole-spin coherence time T2* from 28 ns to 535 ns. Hahn echo preserves the spin coherence on a timescale of 20 {\mu}s, and dynamical decoupling extends the coherence close to the relaxation limit. Both the spin T2* and spin rotation time are much larger than the Purcell-enhanced radiative recombination time, 50 ps, enabling many spin-photon pairs to be created before the spin loses its coherence.

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Mark Hogg, Nadia Antoniadis, Malwina Marczak, Giang Nguyen, Timon Baltisberger, Alisa Javadi, Ruediger Schott, Sascha Valentin, Andreas Wieck, Arne Ludwig, Richard Warburton. 2024-07-26. Fast optical control of a coherent hole spin in a microcavity. https://arxiv.org/abs/2407.18876

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