Two photons in an entangled state of polarization is created by parametric down conversion of a pump light. A first photon of the two photons is sent to a sender while a second photon of the two photons is sent to a receiver. The second photon is divided into a first component and a second component. The receiver makes the first component interact with an isotropic nonlinear optical medium. The sender selects the angle of a polarizer according to a signal that he wants to transmit to the receiver and measures the first photon after it passes the polarizer. The receiver mixes the first component and the second component by a half beam splitter. The receiver knows the signal by measuring the probability of photon detection of two output lights from the half beam splitter.

A topological photonic system configured as a robust source of indistinguishable photons pairs with tunable spectral correlations. The system includes a two-dimensional silicon-photonic ring resonator array configured to implement an anomalous-quantum Hall model that exhibits topologically robust edge states. Linear dispersion of the edge states ensures efficient and robust phase matching and tunability of the spectral bandwidth of photon pairs generated via spontaneous four-wave mixing. Spectral tunability is manifested in the temporal correlations in the Hong-Ou-Mandel interference between photons. The generated photon pairs are energy-time entangled.

A photon source includes a bus waveguide, a photon source pump laser coupled to the bus waveguide and a plurality of optical resonators coupled to the bus waveguide. Each optical resonator of the plurality of optical resonators has a respective resonance line width and a respective resonance frequency, wherein a bandwidth of the resonant center frequencies of the plurality of optical resonators is greater than a bandwidth of the photon source pump laser. The bus waveguide produces photons in response to receiving laser pulses from the pump laser.

Aspects of the present disclosure are directed to photon-pair sources based on an external-cavity laser comprising a gain element and a planar-lightwave circuit that includes a surface-waveguide-based mirror and a ring resonator that enables four-wave mixing, where the surface-waveguide mirror and the ring resonator reside within the gain cavity of the laser itself. As a result, photon-pair sources in accordance with the present disclosure can have: (1) a larger free-spectral range for the entire laser cavity to enable generation of a single wavelength to realize single-mode operation without additional stabilization; and (2) low laser noise, thereby enabling detection and use of the generated photon pairs.

A system for generating clock signals for a photonic quantum computing system includes a pump photon source configured to generate a plurality of pump photon pulses at a first repetition rate, a waveguide optically coupled to the pump photon source, and a photon-pair source optically coupled to the first waveguide. The system also includes a photodetector optically coupled to the photon-pair source and configured to generate a plurality of electrical pulses in response to detection of at least a portion of the plurality of pump photon pulses at the first repetition rate and a clock generator coupled to the photodetector and configured to convert the plurality of electrical pulses into a plurality of clock signals at the first repetition rate.

A method of coding based on transition of lasing and non-lasing states of an optical structure. The power of a single pulse within picosecond-scale time is regulated to achieve transition of lasing and non-lasing states of an optical structure capable of emitting light and having the characteristic of resonant cavity and high Q value along a light path created by a combination of optical elements such as beam splitters, adjustable reflectors and continuously adjustable attenuators. Due to different parameters carried by light radiation in the two states, the parameters correspond to “1” and “0”, respectively. Therefore, binary high-bandwidth coding is realized, and even ternary coding can be realized with a slight improvement on the basis of the light path of binary coding. The tunable bandwidth of coding may reach up to 0.1 THz, which is conducive to promoting the development of high-bandwidth information processing optical microchips.

A photon source includes a bus waveguide, a photon source pump laser coupled to the bus waveguide and a plurality of optical resonators coupled to the bus waveguide. Each optical resonator of the plurality of optical resonators has a respective resonance line width and a respective resonance frequency, wherein a bandwidth of the resonant center frequencies of the plurality of optical resonators is greater than a bandwidth of the photon source pump laser. The bus waveguide produces photons in response to receiving laser pulses from the pump laser.

An imaging system comprises a light source generating a pump beam, and an optical coupling system for receiving an input beam of infrared light from a scene and combining the input beam with the pump beam, wherein an intensity of the pump beam is higher than an intensity of the input beam. The imaging system further comprises a crystal configured for adiabatically mixing the beams and providing an output beam having a frequency which is a sum of frequencies of the input and pump beams, and a visible, near-infrared or ultraviolet light imager configured for collecting and to spectrally resolving the output beam.

Systems and embodiments for an integrated photonics mode splitter and converter are provided herein. In certain embodiments, a system includes a substrate having a first index of refraction. Additionally, the system includes a waveguide layer on the substrate, wherein the waveguide has a second index of refraction different from the first index of refraction. Also, the waveguide layer includes one or more mode splitters that receive at least one of a first photon in a first mode and a second photon in a second mode through an input port and provide one of the first photon through a first output port and the second photon through a second output port. The waveguide layer also includes a mode converter coupled to the second output of a mode splitter, wherein the mode converter receives the second photon through a port and outputs the second photon in the first mode through the port.

A photon source includes a bus waveguide, a photon source pump laser coupled to the bus waveguide and a plurality of optical resonators coupled to the bus waveguide. Each optical resonator of the plurality of optical resonators has a respective resonance line width and a respective resonance frequency, wherein a bandwidth of the resonant center frequencies of the plurality of optical resonators is greater than a bandwidth of the photon source pump laser. The bus waveguide produces photons in response to receiving laser pulses from the pump laser.