Quantum photonic technologies require processing and transport of photonic states containing superposition and entanglement information. For many applications, the ability to transfer the full quantum state of a static particle to a photonic state is crucial. For instance, static qubits can enable indirect photon-photon interactions, and transfer of entanglement between static qubits and photons allows longer distance communications.
In this presentation I will discuss progress on using self assembled quantum dots containing electron spin qubits as a spin-photon interface. I will briefly discuss progress on ultra-bright micropillar cavities with designs demonstrating 69% efficiency and predicting >90% efficiency [1], and previous progress on achieving deterministic interactions between a photon and a quantum dot state [2]. I will then discuss our latest work demonstrating a transfer of the coherent state of an electron spin precessing in a magnetic field to the state of a photon. The coherent state is imprinted onto a narrow bandwidth photon as a phase modulation that oscillates at the electron spin precision frequency. Moreover, for this transfer to occur the spin and photon become entangled with each other in a non-trivial way. To the best of our knowledge no similar phenomenon has been reported in atomic or other quantum emitter systems, but may hold the key to transfer of complex quantum state of light between light and matter systems.[1] Gines et al., “High Extraction Efficiency Source of Photon Pairs Based on a Quantum Dot Embedded in a Broadband Micropillar Cavity” Phys Rev Lett 129, 033601 (2022)[2] P. Androvitsaneas et al. “Efficient Quantum Photonic Phase Shift in a Low Q-Factor Regime”. ACS Photonics 6, 429–435 (2019)