Nanowire quantum dots tuned to atomic resonances

TL;DR

This paper demonstrates the controlled growth and tuning of nanowire-quantum-dot structures on silicon, achieving emission frequencies aligned with atomic transitions, which advances hybrid quantum systems and quantum network applications.

Contribution

It introduces a method for growing and tuning nanowire quantum dots on silicon substrates to match atomic transition frequencies, with precise control over emission wavelength and linewidth.

Findings

Quantum dots tuned to atomic resonances on silicon substrates.

Emission wavelength tunable over 30 nm around 765 nm.

Photon linewidth measured at 9.4 μeV using rubidium transitions.

Abstract

Quantum dots tuned to atomic resonances represent an emerging field of hybrid quantum systems where the advantages of quantum dots and natural atoms can be combined. Embedding quantum dots in nanowires boosts these systems with a set of powerful possibilities, such as precise positioning of the emitters, excellent photon extraction efficiency and direct electrical contacting of quantum dots. Notably, nanowire structures can be grown on silicon substrates, allowing for a straightforward integration with silicon-based photonic devices. In this work we show controlled growth of nanowire-quantum-dot structures on silicon, frequency tuned to atomic transitions. We grow GaAs quantum dots in AlGaAs nanowires with a nearly pure crystal structure and excellent optical properties. We precisely control the dimensions of quantum dots and their position inside nanowires, and demonstrate that the emission wavelength can be engineered over the range of at least $30\,nm$ around $765\,nm$. By applying an external magnetic field we are able to fine tune the emission frequency of our nanowire quantum dots to the $D_{2}$ transition of $^{87}$Rb. We use the Rb transitions to precisely measure the actual spectral linewidth of the photons emitted from a nanowire quantum dot to be $9.4 \pm 0.7 \mu eV$, under non-resonant excitation. Our work brings highly-desirable functionalities to quantum technologies, enabling, for instance, a realization of a quantum network, based on an arbitrary number of nanowire single-photon sources, all operating at the same frequency of an atomic transition.