Efficient photon-pair generation in layer-poled lithium niobate nanophotonic waveguides.

Integrated photon-pair sources are crucial for scalable photonic quantum systems. Thin-film lithium niobate is a promising platform for on-chip photon-pair generation through spontaneous parametric down-conversion (SPDC). However, the device implementation faces practical challenges.

Integrated photonics cascaded attenuation circuit towards single-photon detector calibration.

Integrated photonics platforms are a key driver for advancing scalable photonics technologies. To rigorously characterize and calibrate on-chip integrated photodetectors for ultra-sensitive applications such as quantum sensing and photonic computing, a low-power calibration source down to single-photon levels is required. To date, such sources still largely rely on off-chip bulk or fiber optic setups to accurately attenuate a laser beam referenced to a sub-mW-level primary standard.

Tuning of silicon nitride micro-cavities by controlled nanolayer deposition.

Integration of single-photon emitters (SPEs) with resonant photonic structures is a promising approach for realizing compact and efficient single-photon sources for quantum communications, computing, and sensing. Efficient interaction between the SPE and the photonic cavity requires that the cavity's resonance matches the SPE's emission line. Here we demonstrate a new method for tuning silicon nitride (SiN) microring cavities via controlled deposition of the cladding layers.

Integrated avalanche photodetectors for visible light.

Integrated photodetectors are essential components of scalable photonics platforms for quantum and classical applications. However, most efforts in the development of such devices to date have been focused on infrared telecommunications wavelengths. Here, we report the first monolithically integrated avalanche photodetector (APD) for visible light.

2D Monte Carlo simulation of a silicon waveguide-based single-photon avalanche diode for visible wavelengths.

Integrated photonics platforms are crucial to the development and implementation of scalable quantum information and networking schemes, but many such devices still rely on external bulk photodetectors. We report the design and simulation of a waveguide-based single-photon avalanche diode (SPAD) for visible wavelengths. The SPAD consists of a p-n junction implemented in a doped silicon waveguide, which is end-fire coupled to an input silicon nitride waveguide.

Varying temperature and silicon content in nanodiamond growth: effects on silicon-vacancy centres.

Nanodidamonds containing colour centres open up many applications in quantum information processing, metrology, and quantum sensing. However, controlling the synthesis of nanodiamonds containing silicon vacancy (SiV) centres is still not well understood. Here we study nanodiamonds produced by a high-pressure high-temperature method without catalyst metals, focusing on two samples with clear SiV signatures.

A Metalens with a Near-Unity Numerical Aperture.

The numerical aperture (NA) of a lens determines its ability to focus light and its resolving capability. Having a large NA is a very desirable quality for applications requiring small light-matter interaction volumes or large angular collections. Traditionally, a large NA lens based on light refraction requires precision bulk optics that ends up being expensive and is thus also a specialty item.

Photon bandwidth dependence of light-matter interaction.

We investigate the scattering of single photons by single atoms and, in particular, the dependence of the atomic dynamics and the scattering probability on the photon bandwidth. We tightly focus the incident photons onto a single trapped Rb atom and use the time-resolved transmission to characterize the interaction strength. Decreasing the bandwidth of the single photons from 6 to 2 times the atomic linewidth, we observe an increase in atomic peak excitation and photon scattering probability.

Time-resolved scattering of a single photon by a single atom.

Scattering of light by matter has been studied extensively in the past. Yet, the most fundamental process, the scattering of a single photon by a single atom, is largely unexplored. One prominent prediction of quantum optics is the deterministic absorption of a travelling photon by a single atom, provided the photon waveform matches spatially and temporally the time-reversed version of a spontaneously emitted photon.