Controlled Slowlight and Miniature Devices Based on Silicon Photonics Waveguides

Yurii A. Vlasov, M. O’Boyle, Hendrik F. Hamann +1 more

Diego G. Barreto, Marcos Cordeiro, Eduardo Cesar Rodrigues de Lima +3 more

The use of silicon photonics in the context of quantum technologies has been widely discussed in the fields of communication, engineering, computation, biology, chemistry, and metrology due to its scalability, stability, room-temperature control, and system miniaturization capabilities. In this paper, in the context of using photonic chips for application in quantum information protocols, we focus on multiple waveguide encoding of qudits, that is, a multi-level quantum computational unit, instead of the usual two-level qubit. Given the complexity of constructing control gates and designing systems using qubits, we show a method where we use coupled-mode theory in the small perturbation approximation, so that we can describe the coupling matrix of n-waveguides that can be used in the context of interferometers in photonic chips, to find optimal parameters for describing operations using qudits.

Joshua W. Silverstone, Raffaele Santagati, Damien Bonneau +3 more

Silicon quantum photonics promises to take quantum optics to the large scale, where single photons carry the quantum information which can accelerate difficult computational problems, provide perfectly secure communication, or allow high-accuracy measurements. The silicon photonics platform offers miniature, high-yield, and high-performance photonics which are integrable with CMOS electronics and telecommunications-band optics. To date, only non-scalable photon-pair sources, based on spontaneous four-wave mixing (SFWM) in straight silicon waveguides have been shown to interfere [1]. Until now, single-photon experiments in silicon [2] have exclusively used an off-chip apparatus, such as a silica arrayed waveguide grating, to control and manipulate photon frequency. We present a silicon-on-insulator quantum photonic device (Fig. 1a) able to generate and analyse two maximally entangled qubits. We use this device to demonstrate high-visibility quantum interferencebetween resonant SFWM sources (analogous to [1]), phase-stable frequency-selection, and quantum state tomography. We varied the phase  to obtain the fringes shown in Fig. 1b, with a visibility of 96.8%. This high visibility indicates that the two microring sources are substantially identical. We setup the entangled state via the on-chip 17-dB extinction filters, and used quantum state tomography to analyse it (Fig. 1c). We measured a fidelity of 0.8. This is the first time an entangled state of photonic qubits has been both generated and analysed on-chip, and this generation has been done in a way which is scalable to larger photon number. These results represent a new step towards fully silicon-integrated quantum photonics.

二三夫 小山, FUMIO KOYAMA

Simone Iadanza, Marco Clementi, Sebastian A. Schulz +5 more

A thermo-optic dynamics model and a novel form of induced transparency and corresponding slowlight based on thermo-optic dynamics is demonstrated in optically pumped silicon microcavities. The phenomenon provides group delay as high as 0.5 µs in a silicon photonic crystal cavity at room temperature.

Krauss