Spin-to-polarization mapping with a coherent quantum dot-cavity receiver

Adrià Medeiros; Vincent Vinel; Eliott Rambeau; Petr Steindl; Elham Mehdi; Manuel Gundín; Clément Millet; Petr Stepanov; Niccolo Somaschi; Aristide Lemaître; Isabelle Sagnes; Olivier Krebs; Pascale Senellart; Dario A. Fioretto; Loïc Lanco

arXiv · 2609.03910

Spin-to-polarization mapping with a coherent quantum dot-cavity receiver

Adrià Medeiros·Vincent Vinel·Eliott Rambeau·Petr Steindl·Elham Mehdi·Manuel Gundín·Clément Millet·Petr Stepanov·Niccolo Somaschi·Aristide Lemaître·Isabelle Sagnes·Olivier Krebs·Pascale Senellart·Dario A. Fioretto·Loïc Lanco

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Abstract

Coherent light-matter interfaces controllably modifying the state of a photon upon interaction with a stationary qubit are a key resource for implementing deterministic entangling gates for optical quantum technologies. This requires a one-to-one mapping between the state of the scattered photon and that of the embedded qubit. Here, we present an experimental signature of such a bijection by leveraging the spin-induced Kerr rotation present in a low-noise charged quantum dot-micropillar cavity device. Through time-resolved polarization measurements, we project the electron spin to one of its eigenstates with $95\pm2\%$ fidelity with a single reflected photon detection, and follow the subsequent spin relaxation through the detection of a second reflected photon. We demonstrate that, after a transient regime governed by the trion radiative lifetime, two orthogonal polarization states can be produced, each associated to a given spin eigenstate. While the current results are limited by a timescale competition between electron spin relaxation and trion radiative lifetime, they could be improved using hole spins displaying increased relaxation times. Our work paves the way towards deterministic logic gates exploiting this one-to-one mapping between a spin and the polarization of a scattered photon.

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Adrià Medeiros, Vincent Vinel, Eliott Rambeau, Petr Steindl, Elham Mehdi, Manuel Gundín, Clément Millet, Petr Stepanov, Niccolo Somaschi, Aristide Lemaître, Isabelle Sagnes, Olivier Krebs, Pascale Senellart, Dario A. Fioretto, Loïc Lanco. 2026-09-03. Spin-to-polarization mapping with a coherent quantum dot-cavity receiver. https://arxiv.org/abs/2609.03910

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