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

A quantum entanglement system comprising a laser system, a spontaneous parametric down conversion crystal system, and a thermal management system. The laser system is configured to generate a laser beam. The spontaneous parametric down conversion crystal system comprises a spontaneous parametric down conversion crystal configured to receive the laser beam at a spontaneous parametric down conversion crystal and generate an entangled photon pair in response to the spontaneous parametric down conversion crystal receiving the laser beam. The thermal management system is configured to maintain the spontaneous parametric down conversion crystal at an annealing temperature during a generation of the entangled photon pair. A translation system is configured to move a position of the spontaneous parametric down conversion crystal. A

The invention discloses a rapid biological cell classification imaging method and system based on a quantum correlation diffraction optical neural network, and the method comprises the steps: regulating and controlling a signal photon to an orbital angular momentum state optimized by a neural network based on a time-energy correlation two-photon pair generated in a spontaneous parametric down-conversion process, and irradiating a biological cell sample; a diffractive optical neural network is utilized to construct a quantum state illumination diffractive optical processor, photons carrying cell complex amplitude information are mapped to different detection areas of a predefined image plane, and rapid and high-precision cell classification and recognition are realized through correlation imaging results of an enhanced charge coupled camera. The method has the signal-to-noise ratio and anti-interference capability exceeding the classic limit, can keep high-precision cell classification capability under high background noise, and is suitable for long-time monitoring of living cells under the condition of extremely low light intensity. The method has the characteristics of low energy consumption and high efficiency, and meets the requirements of green calculation and sustainable development. And the method can be used for rapidly classifying and identifying the living biological cells without marks and phototoxicity.

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.

The invention discloses an efficient entangled photon pair preparation method based on a rhombic stacked two-dimensional material, and relates to the field of integrated quantum photonics and advanced nano photonic devices. According to the method, a two-dimensional material waveguide layer with periodic grooves in the light propagation direction is prepared on a substrate, pump light is coupled to a waveguide specific mode, spontaneous parametric down-conversion is completed by means of the second-order nonlinear effect of a two-dimensional material, photon pairs are generated and coupled to different modes of waveguide, and the wavelength of the pump light is changed. Quasi-phase matching is realized by utilizing the periodic grooves so as to compensate phase mismatching, and finally, polarization-coded entangled photons are output. The method is high in efficiency and compact in structure, is compatible with an existing nano photon integration process, provides support for development of an on-chip quantum light source, and is of great significance in promoting practicability of quantum communication and quantum calculation.

The invention belongs to the technical field of quantum optics and quantum information devices, and discloses a near-infrared-mid-infrared dual-wavelength quantum polarization entangled source generating device which comprises a mounting seat, and a near-infrared light source, a mid-infrared light source, a first entangled crystal, a second entangled crystal, a core crystal module, a polarization controller and a generator are mounted and connected above the mounting seat. High-coherence pump light is output through a near-infrared light source, and the high-coherence pump light is shaped into parallel light beams through an aspheric collimating lens group and then is coupled to a first entangled crystal; under a quasi-phase matching condition, the pump light is converted into a near-infrared entangled photon pair of a communication band of 1.5-1.7 [mu] m through a spontaneous parametric down-conversion process, and then the near-infrared entangled photon pair is input into the core crystal module along a preset optical axis; a mid-infrared light source outputs mid-infrared pump light, linear polarization direction locking and polarization state fine regulation and control are completed through a polarization controller, and interference of pump light polarization fluctuation on subsequent entanglement state generation is eliminated; the regulated and controlled mid-infrared pump light is coupled to the second entangled crystal, mid-infrared entangled photon pairs in the atmosphere window wave band of 3.5-4.0 microns are generated through spontaneous parametric down-conversion, the mid-infrared entangled photon pairs are synchronously input into the core crystal module along the optical axis, and actual application and operation are facilitated.

This invention provides a self-calibrated low-light radiance meter and measurement method based on 355nm pumping, including self-calibration and radiation observation. In self-calibration mode, the multiplexed optical path module periodically imports spontaneous parametric downconversion correlated photons, and the photon counting and coincidence detection modules calibrate the absolute quantum efficiency of the three channels. In radiation observation mode, the multiplexed optical path module imports the low-light target radiation, and simultaneously acquires the absolute spectral radiance of the observed target in the 460nm–1550nm band. The calibration coefficients obtained in the self-calibration mode are used to correct the observation results. This invention starts from the basic principle of calibrating the quantum efficiency of single-photon detectors based on the correlated photon method of spontaneous parametric downconversion, realizing high-precision observation of low-light spectral radiance in the visible to near-infrared bands. It solves the scientific problem of traceability of low-light observation instruments on space platforms and plays an important role in climate monitoring, low-light radiation metrology, and single-photon source radiance measurement.

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.

The invention discloses a continuous variable quantum relay method and system based on all-optical entanglement swapping. According to the disclosed scheme, a transmitting end prepares a hyper-entangled photon pair with continuous variable entanglement association on orthogonal amplitude-phase degree of freedom and time-energy degree of freedom at the same time, keeps one group of photons, and transmits the other group of photons to a relay node; at a relay node, quantum purification is firstly implemented based on T-E degree of freedom; then, all-optical entanglement exchange is carried out on the purified photons and photons locally prepared by a relay, and transfer of the X-P degree-of-freedom continuous variable entanglement relation is achieved; reconstructing T-E degree-of-freedom entanglement for the photons after entanglement exchange through a non-degenerate spontaneous parametric down-conversion process; and the plurality of relay nodes are repeatedly executed until the Bob end receives the photon sequence. Probabilistic non-Gaussian measurement is not needed, the structure is simple, the problems that a traditional continuous variable quantum relay is low in generation rate and poor in cascading performance are solved, and the continuous variable quantum relay is suitable for a long-distance continuous variable quantum communication network.

The invention relates to an on-chip entangled photon source based on thin film lithium niobate, which comprises a coupled semiconductor laser, an on-chip beam splitter, a thin film lithium niobate photon chip formed by a first PPLN waveguide, a second PPLN waveguide and an on-chip beam combiner, the on-chip beam splitter outputs split beams to align to the light incident ends of the first PPLN waveguide and the second PPLN waveguide, the on-chip beam combiner inputs to align to the first PPLN waveguide and the second PPLN waveguide, the on-chip beam combiner performs polarization conversion on photon pairs entering through the second PPLN waveguide, then entangles the photon pairs entering through the first PPLN waveguide, outputs entangled photon pairs, and outputs the entangled photon pairs to the light incident ends of the first PPLN waveguide and the second PPLN waveguide. By means of the on-chip structure, the device size can be effectively reduced, beam splitting, spontaneous parametric down-conversion and polarization beam combination are formed in the chip, entangled photon pairs can be effectively and directly generated, and direct polarization entanglement is achieved on the integrated photon chip while the size of the entangled light source device is reduced.

This invention discloses a method and system for measuring single-photon orbital angular momentum Bell states based on a diffractive optical neural network. Based on time-energy correlated photon pairs generated by a spontaneous parametric downconversion process, an interference light field is generated by passing a signal photon modulated into a single-photon orbital angular momentum Bell state through a Bell state evolution system. A diffractive optical processor is constructed using a diffractive optical neural network to map the interference light fields of different Bell states into Gaussian spots in different detection regions within the output plane. Fast and high-precision identification of single-photon orbital angular momentum Bell states is achieved by correlating the imaging results with an enhanced charge-coupled device (CCD) camera. The proposed Bell state measurement method possesses a signal-to-noise ratio and anti-interference capability exceeding the classical limit, maintaining high-precision Bell state identification capability even under high background noise. It exhibits low energy consumption and high efficiency, meeting the needs of green computing and sustainable development. It can be applied to quantum state measurement in the field of quantum information processing.

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.

A stream of photons from an optical source at a source wavelength are converted into entangled photon pairs via a spontaneous parametric down-conversion process. This produces time-synchronized signal and idler photon pairs which share a nominal wavelength, twice the source wavelength, a common polarization. The signal and idler individually have wavelengths that are equally offset above and below their nominal wavelength. The photons segregated into two paths based on wavelength via a wavelength division multiplexer. A phase modulator in the signal path alters the phase of the signal photon, while the idler photon's phase remains unchanged. By applying a modulation signal to the phase modulator, a quantum message is encoded on the photon pair. A multi-channel wavelength division multiplexer may be used to support multiple channels, each carrying signal-idler pairs conveying a quantum encoded message.