223 results about "Quantum entanglement" patented technology

According to some embodiments, system and methods for image improvement comprise: receiving a plurality of frames of a given region of interest, the frames comprised of a plurality of pixels; determining, based on a quantum property of the frames, a normalized pixel intensity value for each pixel of each of the plurality of frames; and generating an improved image of the given region of interest based on the plurality of frames and the corresponding normalized pixel intensity values for the frames, the order of the image being two. Also embodiments for generating an image of a target illuminated by quantum entangled particles, such as, photons, are disclosed.

The disclosed Quantum Optical Coherence Tomography apparatus and method includes a source of quantum entangled photons and a quantum interference device. The pair of entangled photons is divided into two beams, one of which illuminates a semi-reflective object and the second of which is reflected from a variable optical time-delay element (VTE). The VTE is scanned and the quantum interference in the QID is recorded to build up a reflectance profile of the object. A real scanning produces a full tomographic reflectance image. A method of processing the data to eliminate the effects of optical dispersion is disclosed.

According to some embodiments, system and methods for image improvement comprise: receiving a plurality of frames of a given region of interest, the frames comprised of a plurality of pixels; determining, based on a quantum property of the frames, a normalized pixel intensity value for each pixel of each of the plurality of frames; and generating an improved image of the given region of interest based on the plurality of frames and the corresponding normalized pixel intensity values for the frames, the order of the image being two. Also embodiments for generating an image of a target illuminated by quantum entangled particles, such as, photons, are disclosed.

Apparatus and method for producing quantum entangled signal and idler photon pairs is provided. The apparatus makes use of a nonlinear optical fiber to generate the entangled photons. The use of an external broad band light source for alignment of any downstream measurement apparatuses is disclosed. One or more polarized output signals can be generated at both the signal and idler wavelengths using the alignment source, allowing the downstream measurement apparatuses to be aligned using classical light. Multiple signal and idler wavelengths can be generated and aligned using such a system.

The invention provides a generation device for a continuous variable quantum entanglement state light field. The generation device comprises a single-frequency laser (1), an optical parameter amplifier (2), a Bell state direct detection system (3), a bottom plate (4) and an optical parameter amplifier locking system (5); the used optical components are fixed on the bottom plate (4);the optical parameter amplifier locking system (5) is formed by a scanning unit (11), a locking threshold value setting unit (12), a comparison unit (13) and a locking unit (14), therefore, automatic locking for the optical parameter amplifier is achieved, and problems of bad operability and reliability of the conventional continuous variable quantum entanglement source can be solved. The generation device has the advantages of stability, reliability, simpleness in operation and the like and is applicable to volume production.

A quantum entanglement generating system (30) comprises: a laser light source (1) for producing a light beam of light frequency 2f0; a ring interferometer (20) comprising a beam splitter (4) into which the light beam of light frequency 2f0 is incident and a plurality of mirrors (5, 7, 8), the beam splitter and the mirrors forming an optical path in the form of a ring; a parametric amplifier (6) inserted in the optical path of the ring interferometer for producing a beam of light of light frequency f0 upon receiving the light beam of light frequency 2f0 incident into the optical parametric amplifier; and a dispersive medium (9) inserted in the optical path of the ring interferometer for varying relative optical path length for the light beam of light frequency 2f0 and the light beam of light frequency f0, whereby two light beams of light frequency 2f0 split into at the beam splitter (4) so as to travel mutually contrariwise in direction of advance in the ring interferometer are incident into the optical parametric amplifier (6) to generate a first and a second squeezed light beam traveling mutually contrariwise in direction of advance in the ring interferometer (20), and the first and second squeezed light beams upon adjustment of their relative phase at a selected value through the dispersive medium (6) are combined in the beam splitter (4) to generate quantum entangled beams (10, 11).

In one embodiment of the present invention, a quantum entangled photon-pair producing device is disclosed which includes a superposed state generating device for generating a superposed state of photon-pairs entering through N (N≧2) different incident optical paths and being composed of photons having different polarization directions, and a light-guide device for separating the photon-pairs entering through the N (e.g. N is two) incident optical paths into photons having a first polarization direction (e.g. horizontally polarized light) and those having a second polarization direction (e.g. vertically polarized light) and guiding the photons having the first polarization direction and entering through the i-th (1≦i≦N) (e.g. the first) incident optical path and photons having the second polarization direction and entering through the (N−i+1) (e.g. the second) incident optical path to the i-th (e.g. the first) exit optical path through optical paths having the same optical path length. Therefore, quantum entangled photons of N channels having a quantum correlation with regard to the polarization direction can be produced. With this, a quantum entangled photon-pair producing device capable of producing quantum entangled photon-pairs of multi-channel having a quantum correlation with regard to the polarization direction with high production efficiency is realized.

The invention relates to a multi-hop lossless teleportation method based on a non-maximum entangled chain channel. Alice and Bob, which do not directly share a quantum entanglement pair at the beginning, continuously carry out entanglement exchange through the help of p middle nodes; finally, a quantum entanglement channel is constructed; and the multi-hop teleportation process of the sender Alicetransmitting a single-particle multi-energy level unknown quantum state to the receiver Bob is completed. The method in the invention uses the non-maximum entangled chain channel; even the sender andthe receiver do not directly share the quantum entanglement pair, the quantum state information can be still transmitted between both the sides; and the requirement for constructing a complex quantumcommunication network can be satisfied; in the multi-hop lossless teleportation system in the invention, if the teleportation process is successfully executed, the information receiver Bob can obtainthe transmitted quantum state information; if the teleportation process fails, the information sender Alice can restore the transmitted unknown quantum state information; and the unknown quantum state information is not lost.

The invention provides a total probability arbitrary multiparty JRSP method. According to the method, a core sender constructs a real part measurement base in accordance with real part information of quantum states needing to be prepared, particles owned by the core sender are measured, and measuring results are sent to corresponding auxiliary senders and receivers through classical channels; all the auxiliary senders construct imaginary part measurement bases by the adoption of the measuring results and owned imaginary part information, particles owned by the auxiliary senders are measured respectively, and measuring results are sent to the receivers through classical channels; at last, the receivers conduct certain unitary operation on the particles in hands according to the measuring results of the core sender and the measuring results of all the auxiliary senders, and the particles needing to be prepared are obtained. By means of the total probability arbitrary multiparty JRSP method, the methods of quantum information fragmentation, quantum entanglement and quantum measurement are used, arbitrary multiparty JRSP is achieved, and the method is safe and reliable, flexible and universal, and good in practical value.

The invention discloses a clock synchronization system and method based on quantum entanglement. The system includes an entanglement source unit, a transmission unit, a clock synchronization unit Alice, a clock synchronization unit Bob and a measurement unit. According to the system, entangled photons of a single polarization state are employed as synchronization signal carriers, and Faraday mirrors and bidirectional paths are utilized to realize automatic compensation of polarization jitters in optical fiber, frequency-approximated entangled photon pairs are formed by a 790nm laser-pumped type-II phase-matched crystal, and delay time of the two optical paths is precisely controlled through an electrically controllable optical delay line, a maximum value of an HOM sag between the two partsof to-be-carried-out clock synchronization is obtained, thus accurate time difference with a benchmark as an intermediate unit is obtained, and then clock synchronization of the two parts is realizedthrough direct measurement of the entangled photons.

The invention provides a device and a method for generating a photo-communication waveband continuous variable quantum entanglement source. The device comprises a photo-communication waveband continuous single-frequency fiber laser, a frequency multiplier, a signal light mode cleaner, a pump light mode cleaner, a dichroic mirror, a total reflection plane mirror with piezoelectric ceramics, a three-resonance non-degeneracy optical parametric amplifier, a crystal temperature controller, a cavity length and phase locking system, a first 45-degree high reflecting plane mirror and a quantum entanglement source detection system. According to the device and the method for generating the continuous variable quantum entanglement source, the device has a compact structure, is high in stability and is matched with the photo-communication waveband; the device adopts a single three-resonance non-degeneracy optical parametric amplifier for directly preparing the photo-communication waveband continuous variable quantum entanglement source, and the transmission loss of the waveband quantum entanglement source in optical fiber is only 0.2dB / km, so that the high fidelity transmission of information is realized; and the device is compatible with the present photo-communication system, so that the quantum entanglement source can become a perfect light source of a practical quantum network.

The invention provides a device and a method for automatically adjusting classical gain in a continuous variable quantum entanglement source. The device comprises an optical parameter amplifier, a photoelectric detector, a central processing unit and a temperature controller, wherein a working temperature adjustable nonlinear crystal is placed in the optical parameter amplifier; the photoelectric detector converts an optical signal transmitted by the optical parameter amplifier to an electrical signal; the electrical signal is input to the central processing unit by an analog / digital converter; a signal output by the central processing unit is input to the temperature controller by a digital / analog converter; the temperature of the nonlinear crystal is controlled by the temperature controller; and the method for automatically adjusting the classical gain comprises the steps that the photoelectric detector monitors a transmission signal of the optical parameter amplifier, and the working temperature of the nonlinear crystal is adjusted by a detection result, so that a peak-peak value of the transmission signal is maximum, that is the classical gain is maximum. The device solves the problem that the existing continuous variable quantum entanglement source is difficult to operate, and lays a foundation for the device from a laboratory to a market.

The invention relates to a method and a system for improving the positional accuracy of a Beidou navigation system by using photon pairs with a quantum entanglement feature. The method includes following steps: 1), producing the photon pairs with the quantum entanglement feature; 2), respectively sending the photon pairs with the quantum entanglement feature produced in step 1) to a first clock and a second clock in need of clock synchronization and recording the time from photons to the first clock and the second clock; 3), enabling two photons to pass through a beam splitter, and acquiring the time from the photons to the beam splitter; 4), acquiring a timing difference of the first clock and the second clock; and 5), adjusting the timing difference of one of the clocks according to the acquired timing difference of the two clocks so as synchronizing the two clocks. By the aid of the method and the system, the positional accuracy of the Beidou navigation system is evidently improved.

A method for generating a quantum-entangled photon pair is such that a biexciton in such a state that the angular momentum is 0 is generated through two-photon resonance induced by irradiating a semiconductor substance, e.g., CuCl, with two parent photons (angular frequency ωi). A photon pair is then generated by splitting the biexciton thus generated simultaneously into two photons (angular frequencies ωs and ωs′). Since the photon pair is generated by splitting such biexciton having an angular momentum of 0, it has a quantum entanglement with regard to polarization. Since the photon thus generated has a wavelength substantially equal to that of the parent photons, photons of shorter wavelength in a quantum entangled state can be generated.

A non-degenerate polarization-entangled photon pair generation device (1) that efficiently and easily generates non-degenerate polarization-entangled photon pairs includes: a quantum-entangled photon pair generator (2) including a single crystal in which periodically poled structures (3a, 3b) having different periods are formed; and a light radiating unit (4) for entering light into the quantum-entangled photon pair generator (2) such that the light passes through the periodically poled structure (3a) and then through the periodically poled structure (3b). A period of the periodically poled structure (3a) is different from a period of the periodically poled structure (3b) such that a parabola indicative of a relation between an emission angle and a wavelength of a polarized photon emitted based on light incident on the periodically poled structure (3a) comes into contact with a parabola indicative of a relation between an emission angle and a wavelength of polarized photon emitted based on light incident on the periodically poled structure (3b), within an allowable range under a phase matching condition.

A method and apparatus comprising a source node. The source node is configured to transmit information using particles with quantum entanglement in a network configured to transmit the information over a reserved path during selected time intervals.

The invention discloses a sandwich type high light quantum entanglement photon source which comprises a pump laser light source and a crystal mechanism. The crystal mechanism is used for receiving pump laser light emitted by the pump laser light source and producing two down-conversion beams provided with entanglement photon pairs. The crystal mechanism comprises two non-linear crystals and a semi-wave plate arranged between the two non-linear crystals. The two non-linear crystals meet II type phase matching. Working wavelength of the semi-wave plate is identical with wavelength of the quantum entanglement photon source. The direction of an optical axis of the semi-wave plate forms an angle of 45 degrees with a plane. The plane is determined by the direction of optical axes of the two non-linear crystals and the direction of the pumping laser light. The sandwich type high light quantum entanglement photon source is convenient to adjust, high in integration degree, beneficial to expansion and capable of being applied to application fields of quantum communication, quantum cryptography and the like.

Apparatus for transmitting and receiving information using one or more quantum-entangled particles. The apparatus may include a first substrate including a first row of quantum dots and a second substrate including a second row of quantum dots. The apparatus may also include a beam splitter configured to inject a first particle into a first quantum dot and to inject a second particle into a second quantum dot. A physical property of the first particle may be in a quantum-entangled state with a physical property of the second particle. The apparatus may further include a first wave source configured to move the first particle along the first row of quantum dot, and a second wave source configured to move the second particle along the second row of quantum dots.

The invention discloses a quantum entanglement detection method and device, electronic equipment and a storage medium, and relates to the technical field of quantum computing. The method comprises thesteps of obtaining a parameterized quantum circuit, the parameterized quantum circuit acts on two initial quantum states to obtain two first quantum states, and the parameterized quantum circuit comprises adjustable parameters; obtaining a loss function based on a to-be-measured sub-state and the two first quantum states; minimizing the loss function, and obtaining a value of the minimized loss function; and detecting whether the to-be-measured sub-state is an entangled state based on the value. The quantum entanglement detection method is simpler and easier to implement for detecting whetherthe quantum is in the entanglement state, and the workload of quantum entanglement detection is reduced.

The invention relates to a generation device of quantum entanglement among three atomic ensembles, and mainly aims to solve the existing technical problem of probability preparation existed by quantum entanglement among a plurality of atomic ensembles. The invention adopts the technical scheme that the generation device of quantum entanglement among the three atomic ensembles comprises a light source unit, nine acousto-optic modulators, three sets of optical parametric amplifiers, a beam coupling system, the three atomic ensembles, three sets of optical filtering systems and an entanglement measurement system. Under the light writing action of quantum memory, orthogonal component quantum states of three entangled light pulses are mapped into collective spin waves of the three atomic ensembles, and quantum entanglement among the three atomic ensembles is certainly established; then, under the light reading action of quantum memory, the collective spin wave quantum states of the three atomic ensembles are mapped into the orthogonal component quantum states of the three release light pulses, and quantum entanglement among the three atomic ensemble is certainly verified through measuring correlative characteristics of the orthogonal component quantum states of the three release light pulses and the collective spin waves of the three atomic ensembles.

The invention relates to a generating device for entanglement of continuous variable atom ensemble and belongs to the generating device for the entanglement of atom ensemble applied to a quantum information network. The generating device is used for solving the technical problem that probability preparation exists in the present preparation for the entanglement of atom ensemble of variables separation. According to the technical scheme provided by the invention, the generating device for entanglement of continuous variable atom ensemble comprises a light source unit, a plurality of beam coupling systems, two sets of atom ensembles, an entanglement measuring system and a feedback unit. The orthogonal component of a light field in the continuous variable quantum information and the collective spin wave of the atom ensemble are utilized to generate the entanglement of two sets of stokes light and spin wave of atom ensemble in a spontaneous raman scattering process, and then interference signals of the two beams of stokes light are fed back to a first atom ensemble through the quantum entanglement exchange, the entanglements of the first atom ensemble and the second atom ensemble are certainly prepared, and the generated stokes light is utilized to measure and analyze the entanglement of the atom ensemble.

A method and apparatus for transmitting information using the phenomenon of quantum entanglement. Two streams of quantum-entangled particles are emitted from a source. Performing a measurement on one of the streams results in the observable destruction of interference on the other stream. Information is transmitted by modulating the performance of the measurement on the first stream, and received by observing the presence or absence of interference in the second stream.

The invention provides a measurement-retransmission semi-quantum private comparison method without entanglement, which uses the product state of two particles as an initial quantum preparation resource. Two classical users can achieve their secret equality comparison with the help of a quantum third party, and the quantum third party is semi-loyal, which means that the quantum third party is allowed to act wrongly according to the own will but cannot collude with the users. According to the scheme of the invention, the output correctness and the security performance against external attacks and participant attacks can be guaranteed. Compared with the previous semi-quantum private comparison method, the method of the invention has the advantages that only the product state of two particlesis used as the initial quantum preparation resource, only the third party is required to perform single photon measurement, and quantum entanglement swapping is not required. The method of the invention can be realized by an existing quantum technology.

The invention discloses a two-party quantum private comparison method based on a five-quantum bit entangled state. The two-party quantum private comparison method is used for comparing whether secrets of two users are equal or not in size. The two-party quantum private comparison method has the advantages that the method needs help of a semi-loyal third party (Third Party, TP), the TP is allowed to mistakenly act according to the wish of the TP, but is not allowed to conspire with any one of the two users; one five-quantum bit entangled state can be used for achieving two-bit equality comparison in all comparison; unitary operation and the quantum entanglement swapping technology are not required in the method, it is avoided that expensive quantum devices related by unitary operation and the quantum entanglement swapping technology are consumed; Bell measurement and single-particle measurement are only adopted in the method, and the quantum measurement can be achieved with the existing quantum technology; safety performance according to outside attack and participant attack is guaranteed; secret information and the comparative result of the two users are not revealed to the TP.

The invention discloses a quantum identity authentication method and an application method of the quantum identity authentication method in a quantum key distribution process. Mutual identity authentication between two participants can be realized. The security is based on a quantum mechanics basic principle and is independent of the computation capability of an attacker. When the method is realized, technologies such as quantum storage, quantum entanglement and multiparticle measurement do not need to be used, so the scheme is has the characteristics of simpleness and easiness in realization. Compared with the prior art, the method has the positive effects that the method provided by the invention is clear in principle, a realization method is simple, the security is high, and an entanglement source and multiparticle measurement and quantum storage technologies do not need to be used, so the realization can be achieved under an existing technological condition. Related authentication schemes can be applied to establishment of a high-security quantum identity authentication system with the quantum computation resistance capability and also can be applied to a current mainstream quantum key distribution system, thereby realizing the high-security identity authentication between two communication parties.

The invention belongs to the field of quantum information, in particular to a method for generating two-photon radiation on the basis of a single quantum dot. Generation of two photons has great significance in the quantum information field such as quantum key distribution, quantum entanglement, quantum measurement and the like. The method for generating two-photon radiation on the basis of the single quantum dot is provided and comprises steps as follows: firstly, a near infrared single quantum dot is prepared on a slide with a indium tin oxide film formed through evaporation plating; then, indium tin oxide nanoparticles cover the single quantum dot; the indium tin oxide nanoparticles are spin-coated with polystyrene polymer films, and influence of the external environment on the quantum dot is effectively isolated; laser co-focusing is performed on the sample, and two-photon fluorescence radiation is generated for the single quantum dot. With the adoption of the indium tin oxide nanoparticles, nonradiative auger recombination of biexciton of the quantum dot is effectively inhibited, and two-photon radiation of the single quantum dot is realized.

According to some embodiments, system and methods for image improvement comprise: receiving a plurality of frames of a given region of interest, the frames comprised of a plurality of pixels; determining, based on a quantum property of the frames, a normalized pixel intensity value for each pixel of each of the plurality of frames; and generating an improved image of the given region of interest based on the plurality of frames and the corresponding normalized pixel intensity values for the frames, the order of the image being two. Also embodiments for generating an image of a target illuminated by quantum entangled particles, such as, photons, are disclosed.

The invention provides a navigation and distance measurement system on the basis of quantum entanglement light. The navigation and distance measurement system comprises a quantum entanglement light source module, single-photon detectors, a data acquisition module and a data processing module. The quantum entanglement light source module is used for generating entanglement double-photon pairs, the entanglement double-photon pairs are respectively fed into a test light path and a reference light path, and the data acquisition module is used for respectively acquiring time-domain count pulses generated by the single-photon detectors in the test light path and the reference light path and respectively recording arrival time of the time-domain count pulses generated by the single-photon detectors in the test light path and the reference light path; the data processing module analyzes data acquired by the data acquisition module, so that time sequence tags of the test light path and the reference light path can be acquired, and distances to be measured can be computed according to the time sequence tags by the aid of a conformation algorithm. The navigation and distance measurement system has the advantage that the distances can be precisely measured by the navigation and distance measurement system on the basis of a second-order correlation characteristic of the quantum entanglement light and corresponding data processing algorithms.

The invention discloses a node trust-based quantum trust assessment method, including modeling of a quantum trust model and a method for quantum trust assessment. Compared with the prior art, the method uses a trust node-based credible quantum relay network as a research object, introduces trust management into a quantum communication network, uses assessment of a trust value of a node as a basis to build a safe and credible quantum communication network, and uses the trust value as a basis for judging whether users in the quantum communication network are credible; by means of unique characteristics of a quantum entanglement effect and quantum teleportation, the node trust-based quantum trust assessment method is researched and proposed, and the idea and the process of quantum trust assessment are explained in detail; and finally feasibility, reasonability and safety of the node trust-based quantum trust assessment method proposed by the invention are analyzed, thereby providing a valuable new idea and new method for building a safe and credible quantum communication network.