Mid-infrared quantum optics in silicon.

Applied quantum optics stands to revolutionise many aspects of information technology, provided performance can be maintained when scaled up. Silicon quantum photonics satisfies the scaling requirements of miniaturisation and manufacturability, but at 1.55 µm it suffers from problematic linear and nonlinear loss. Here we show that, by translating silicon quantum photonics to the mid-infrared, a new quantum optics platform is created which can simultaneously maximise manufacturability and miniaturisation, while reducing loss. We demonstrate the necessary platform components: photon-pair generation, single-photon detection, and high-visibility quantum interference, all at wavelengths beyond 2 µm. Across various regimes, we observe a maximum net coincidence rate of 448 ± 12 Hz, a coincidence-to-accidental ratio of 25.7 ± 1.1, and, a net two-photon quantum interference visibility of 0.993 ± 0.017. Mid-infrared silicon quantum photonics will bring new quantum applications within reach.

Observation of nonlinear interference on a silicon photonic chip.

Photonic integrated circuits represent a promising platform for applying quantum information science to areas such as quantum computation, quantum communication, and quantum metrology. While the linear optical approach has greatly contributed to this field, it is often possible to improve the functionality and scalability by making use of nonlinear processes. One interesting phenomenon is the interference between two nonlinear optical processes, where the interference occurs by removing the information as to which of two processes have occurred. In this Letter, we demonstrate a nonlinear interferometer in the pair-photon generation regime by using spontaneous four-wave mixing in an integrated silicon photonic chip. We observe a nonlinear interference in the production rate of photon pairs generated from two different four-wave mixing waveguides. We obtain an interference visibility of 96.8%. This work shows the possibility of integrating and controlling nonlinear-optical-interference components for silicon quantum photonics.

On-chip quantum interference with heralded photons from two independent micro-ring resonator sources in silicon photonics.

High visibility on-chip quantum interference among indistinguishable single-photons from multiples sources is a key prerequisite for integrated linear optical quantum computing. Resonant enhancement in micro-ring resonators naturally enables brighter, purer and more indistinguishable single-photon production without any tight spectral filtering. The indistinguisha-bility of heralded single-photons from multiple micro-ring resonators has not been measured in any photonic platform. Here, we report on-chip indistinguishability measurements of heralded single-photons generated from independent micro-ring resonators by using an on-chip Mach-Zehnder interferometer and spectral demultiplexer. We measured the raw heralded two-photon interference fringe visibility as 72 ± 3%. This result agrees with our model, which includes device imperfections, spectral impurity and multi-pair emissions. We identify multi-pair emissions as the main factor limiting the nonclassical interference visibility, and show a route towards achieving near unity visibility in future experiments.

Chairside polishing of heat-cured acrylic resin: an SEM and EDA study.

PURPOSE: This study investigated the surfaces produced on two commonly used heat-cured acrylic resins by two chairside polishing systems compared to conventional lathe polishing. It used energy dispersive analysis (EDA) and scanning electron microscopy (SEM) to investigate the abrasive materials bonded in the silicone points that are marketed for chairside polishing of acrylic resin. MATERIALS AND METHODS: Using the three polishing systems (conventional as control, Shofu acrylic polishing system [AcryPoint], and Kenda Queen silicone polisher), three operators polished specimens using a defined protocol. Specimens were subjected to SEM and confocal microscopy. EDA was undertaken on the silicone polishing points. RESULTS: Conventional polishing produced the superior surface, followed by the surfaces produced by the Shofu system and then Kenda Queen. However, both chairside polishing systems produced smoother surfaces on acrylic resin than the surfaces produced by either steel or tungsten carbide burs. Both the Shofu acrylic polishing system and Kenda Queen silicone polisher contain beads of cerium, which is widely used in industry for polishing of glass. CONCLUSION: Silicone polishing points marketed for polishing of acrylic resin could be used to produce smooth surfaces that have been adjusted with burs where there is no access to a laboratory lathe.

Dimensional change in dentures processed in silicone and stone moulds.

Anecdotal evidence suggests that many dental laboratories are surrounding the teeth and gingival margins of the wax patterns for complete dentures with silicone laboratory putty prior to investing in dental stone or plaster to facilitate deflasking and polishing. This project investigates differences in dimension during processing when putty is used. Two groups of ten standardised dentures, one group with silicone, one group without were processed. Cross arch measurements were made before and after processing using an eight hour curing cycle followed by slow cooling. No statistically significant difference in change in dimension was observed between the two groups, indicating that this is an acceptable method.