3 results about "Spontaneous parametric down-conversion" patented technology

This invention proposes a multi-target detection method based on entangled photons. First, a pump light is generated using a continuous narrow-linewidth semiconductor laser, which, after polarization modulation and focusing, illuminates a PPKTP crystal. A spontaneous parametric down-conversion process generates polarization-entangled photon pairs, which are then separated into signal and reference light. These are received by a single-photon detector to obtain two time series. Second, coincidence measurements are performed on the time series in different scanning directions within the observation area to obtain a coincidence count matrix. Then, a two-dimensional constant false alarm rate (CFAR) detection algorithm is introduced, using ordered statistics to estimate background noise and adaptively adjust the detection threshold to screen candidate target points. Third, a density clustering algorithm based on correlation strength weighting is employed, combining the correlation strength and spatial distribution of entangled photon pairs to detect different targets and suppress isolated noise. Finally, the coincidence count peak points within each target cluster are selected as the final detection targets, thereby achieving multi-target detection with unknown numbers and randomly distributed locations.

This invention provides a waveguide assembly, a control method for the waveguide assembly, an optical chip, and an optical quantum computer. The waveguide assembly includes: a waveguide body having a preset polarization period in the direction of optical signal propagation; multiple heating devices for heating different regions of the waveguide body; and a controller for controlling the multiple heating devices to heat corresponding regions of the waveguide body to different temperatures, enabling the waveguide body to undergo spontaneous parametric switching at different frequencies, generating quantum entangled light sources in different bands. This waveguide assembly, while meeting the requirements for generating broadband quantum entangled light sources, reduces dependence on waveguide process parameters, thereby reducing the difficulty of waveguide manufacturing.

This invention discloses an on-chip integrated beam-splitting polarization-entangled photonic array chip, belonging to the field of integrated quantum mechanics. The chip includes a pump laser input terminal, an on-chip beam-splitting structure, and a Bragg reflection waveguide array. After the pump light is coupled into the chip, it undergoes progressively uniform power distribution through a beam-splitting structure composed of multiple cascaded Y-beam splitters and is injected into multiple Bragg reflection waveguides. The Bragg reflection waveguides are constructed based on AlGaAs / GaAs materials to form a non-ideal quarter-wavelength structure, efficiently generating polarization-entangled photon pairs through a spontaneous parametric down-conversion process. This invention achieves monolithic integration of pump light beam splitting and entangled photon generation, offering advantages such as low loss, uniform splitting ratio, good output consistency, high integration density, and strong compatibility. It is suitable for applications in quantum imaging, quantum communication, and parallel quantum information processing.