Integrated sources of photon quantum states based on nonlinear optics

The ability to generate complex optical photon states involving entanglement between multiple optical modes is not only critical to advancing our understanding of quantum mechanics but will play a key role in generating many applications in quantum technologies.These include quantum communications,computation,imaging,microscopy and many other novel technologies that are constantly being proposed.However,approaches to generating parallel multiple,customisable bi-and multi-entangled quantum bits(qubits)on a chip are still in the early stages of development.Here,we review recent advances in the realisation of integrated sources of photonic quantum states,focusing on approaches based on nonlinear optics that are compatible with contemporary optical fibre telecommunications and quantum memory platforms as well as with chip-scale semiconductor technology.These new and exciting platforms hold the promise of compact,low-cost,scalable and practical implementations of sources for the generation and manipulation of complex quantum optical states on a chip,which will play a major role in bringing quantum technologies out of the laboratory and into the real world.

Ultra-high suppression microwave photonic bandstop filters

A bandstop radio frequency(RF)filter can enhance the capabilities of RF communication systems by removing unwanted signal components such as distortion,or interference.In modern cognitive radio systems,frequency agile filters are desired to block interferers with dynamically changing frequencies and powers.These filters should be tunable over a broad frequency range,and they should be capable of suppressing very strong signals with a high resolution.To simultaneously meet these requirements with traditional RF filters are highly challenging.Microwave photonic(MWP),a technology that primary deals with the generation,distribution,and processing of high speed RF signals using photonic techniques and components,is promising for creating frequency agile RF filters.However,traditional MWP filters are lacking the high resolution and peak suppression exhibited by state-ofthe-art RF electrical filters.We recently introduced a new class of MWP notch filter which is free from this limitation.This scheme allowed the creation of anomalously high suppression MWP notch filter from virtually any kind of optical resonance,irrespective of its type(gain or absorption),or its magnitude.This enabled,for the first time,simultaneous optimization of the MWP filter resolution,peak attenuation,and frequency tuning range.In this paper,we present the analysis of notch filter response creation using the novel sideband processing technique.We thenshow the applicability of this technique to a wide range of optical filters.We compare simulated and experimental results of the notch filter response created using three types of optical filter commonly used in MWP signal processing,namely stimulated Brillouin scattering(SBS),an integrated optical ring resonator(ORR),and a phase-shifted fiber Bragg-grating(FBG).