49 results about "Photon polarization" patented technology

A system and method for quantum key delivery in a single-photon, free-space cryptography scheme including a transmitter and a receiver. The transmitter includes two pairs of photon sources, each of which represents a specific photon polarization direction. The first pair of photon sources represents a first polarization basis while the remaining pair of photon sources represents a second polarization basis. The first and second polarization basis are rotated with respect to each other so as to produce non-orthogonal polarization eigenstates. A transmitter polarizing beamsplitter corresponding to each of the pairs of the photon sources is provided whereby the polarizations of each of the photon sources of each pair of photon sources are recombined. A transmitter non-polarizing beamsplitter is provided whereby the recombined polarizations are combined for output to the receiver. The receiver includes a set of optics inversely disposed with respect to the optics of the transmitter and two pairs of photon detectors.

The invention solves the following complicated problems. Elaboration of the procedure for secret key extraction from the lower layer optic signal even in a presence of noise in fiber-optic cable. The realization of the quantum protection amplification scheme to clean states of the entangling polarized photons against noise in optical channels, especially in case of use Einstein-Podolsky-Rozen method with single photon source for transmitting and measuring secret keys photon polarization in ROADM network. The development of a system for code key transmission that satisfies requirements of fortuitousness and privacy along with speed enlargement of the key generation in ROADM network. The achievement of the acceptable optical fiber amplification without losing its behavior and the protocol determination, which will allow to detect and correct bit errors in fiber optic cable and ROADM network, caused by linear and nonlinear effects. The development of quantum encoding systems for telecommunication topologies.

The invention relates to a single-photon polarization self-calibrating and locking method and device based on a phase encoding quantum key distribution (QKD) system and a single-photon polarization control based on phase encoding quantum key distribution system. The polarization control scheme is divided into a calibration process and a locking process which are automatically switched through judging the threshold of a feedback signal. According to the scheme, efficient automatic polarization calibration and locking are realized through the matching of a polarization beam splitter, a multi-degree-of-freedom polarization controller and a genetic algorithm; a polarization feedback circuit device comprises the polarization beam splitter, a polarization controller, a single-photon detector, a signal acquiring and processing module and corresponding control circuits. By using the polarization control method, polarization can be continuously and precisely controlled without reset operation in real time under the condition that the strength of the feedback signal is in the single-photon magnitude, and human intervention is not needed in the whole control process.

The invention relates to frequency lock of a laser device in the 1529 nm optical communication wave band, in particular to a method and device for stabilizing the 1529 nm optical fiber communication laser frequency to solve the technical problem that an existing laser frequency stabilization technology for the 1529 nm optical communication wave band is affected by noise brought by frequency modulation. The method for stabilizing the 1529 nm optical fiber communication laser frequency includes the following steps of firstly, converting a bundle of 780 nm laser locked by a polarization spectrum into a sigma+ circularly polarized light, and leading the circularly polarized light to a rubidium bubble filled with rubidium 87 steam; secondly, leading a bundle of linear polarization laser outputted by a 1529 nm semiconductor laser device to the rubidium bubble; thirdly, dividing a 1529 nm laser emitted from the rubidium bubble into two bundles of light with the perpendicular polarization directions, collecting magnitude signals of the two bundles of light, converting the magnitude signals into corresponding electrical signals respectively, and subtracting one of the electric signals from the other electrical signal to obtain a two-photon polarization spectrum signal; fourthly, feeding the two-photon polarization spectrum signal back to the 1529 nm semiconductor laser device. The method and the device can be applied to the superfine spectrum field, the frequency standard field, the precision measurement field and other fields.

The invention discloses a plug-and-play measuring device independent quantum key distribution network system and a method. The method includes steps: a quantum relay unit emits two channels of pulses,the pulses are respectively transmitted to two designated quantum terminal units through a quantum channel, the quantum terminal units encode the input light pulses and transmit the pulses back to the quantum relay unit through the quantum channel, and the quantum relay unit conducts a Bell-state analysis on the pulses modulated through the quantum terminal units, obtains a result and publishes the result through a classic channel; and the quantum terminal units compare the above result and local encoding information, obtains a screening node and selects a part for error code rate detection,if the result is safe, the communication is successful, and if the result is not safe, the communication is given up and restarted. The problems of the influence of the environment on photon polarization in practical application and key distribution multi-user application in the network are solved.

The invention discloses a polarization multiplexing microwave photon radar detection method and system based on photon sampling. The detection method comprises the steps that an optical frequency combsignal is divided into two paths, the baseband linear frequency modulation signal and the target echo signal respectively modulate one path of optical frequency comb signal to obtain an emission modulation optical signal and a reception modulation optical signal with orthogonal polarization states; the emission modulation optical signal and the reception modulation optical signal are combined into one path of polarization multiplexing optical signal and then are divided into two paths; two paths of signals are respectively analyzed to obtain an emission modulation optical signal and a composite optical signal containing the emission modulation optical signal and the reception modulation optical signal, the composite optical signal is subjected to photoelectric conversion and low-pass filtering to obtain an intermediate frequency signal, and the intermediate frequency signal is processed to obtain detection target information. Through a photon sampling technology and a photon polarization multiplexing technology, broadband and frequency band adjustable radar signals are generated and received, and a radar system is compact and simple and can be integrated.

The invention relates to an extremely-weak optical signal degree of polarization detection system and a detection method based on the same system, and relates to the technical field of laser radar. The invention aims to solve the problem that when the existing laser radar detects a very long distance target, the obtained information is single and the judgment and recognition of the target cannot be effectively performed. The extremely-weak optical signal degree of polarization detection system and the detection method based on the same system radiate the target with an optical signal subjected to polarization modulation, split the echo signal light into four ways, and use Gm-APD for performing photon counting. According to the counting result, the photon polarization information of the echo signal light is obtained, so as to achieve the purpose of identifying the target. The invention uses Gm-APD for photon counting, the response sensitivity has reached a single photon level, breaking the counting bottleneck of the traditional radar, and according to the response counting, an extremely weak signal polarization solution is achieved. The method and the system provided by the invention are applicable to long-distance target identification and detection and weak light optical detection of the single photon level.

A cryptography method using a quantum phenomenon, which performs a multi-staged polarization process between a transmitter and a receiver to prevent a third party from knowing the polarization value of a photon. A transmitter rotates a photon flux by arbitrary angle θ and transmits it to a receiver. The receiver rotates the received photon flux by arbitrary angle φ and transmits it to the transmitter. The transmitter rotates the received photon flux by the reverse angle −θ of an angle, by which the transmitter 10 rotated it, then rotates it by polarization corresponding to an information bit, and transmits it to the receiver which rotates the received photon flux by the reverse angle −φ of an angle, and measures the polarization of the photon flux corresponding to the information bit, and recovers the information bit transmitted by the transmitter. Cryptography information may be transmitted using a plurality of photon fluxes.

A quantum digital signature system resistant to polarization disturbance comprises a message sender Alice, two message receivers Bob and a receiver Charlie, the sender Alice sends a message to the receiver Bob and the receiver Charlie in combination with a digital signature, the receiver Bob serves as a message authenticator and forwards information sent by the sender Alice to the receiver Charlie, and the composition of the receiver Charlie is completely the same as that of the receiver Bob. Compared with the prior art, the quantum digital signature scheme based on the phase coding BB84 quantum key distribution system can resist channel polarization disturbance. The photon polarization state change caused by channel disturbance does not influence the final interference result of the system, namely, the stability of the system can be ensured.

The invention relates to a bit error rate and uncertainty joint feedback photon polarization state compensation method. The method includes the following steps that: a quantum key distribution system publicizes N bits in an original key of which the length is M every time which are used for bit error rate statistics, wherein N is far smaller than M; the quantum key distribution system publicizes an N'-bit pseudo key in an effective detection sequence where the original key is located, wherein the N'-bit pseudo key is used for uncertainty statistics; and simultaneous compensation of two non-orthogonal polarization states |+> and |H> can be realized through utilizing photon polarization states of the bit error rate and the uncertainty on the estimating receiving end of a Poincare sphere. With the bit error rate and uncertainty joint feedback photon polarization state compensation method of the invention adopted, the two non-orthogonal photon polarization states can be accurately compensated in real time under the situation that the communication efficiency and distance of the quantum key distribution system are not affected and the cost of the system is not increased.

The invention discloses a subject and object compounded multi-photon polarization laser material based on a metal-organic framework and a preparation method of the subject and object compounded multi-photon polarization laser material. The material comprises a subject and an object, wherein the subject adopts a metal-organic framework material, adopts a three-dimensional net structure constructed by zinc ions and a multi-tooth organic ligand 7-(4-carboxyphenyl)-3-carboxy-quinoline through a coordination bond and has a one-dimensional channel; the object adopts dye ions. By means of the chemical compatibility of the metal-organic framework material as the subject with a dye as the object and the efficient confinement function of the one-dimensional channel of the metal-organic framework material, the prepared subject and object compounded material can obtain high-concentration, uniform and highly oriented dye loading while keeping higher fluorescence quantum efficiency and can realize conversion of the laser wavelength from infrared frequency to the frequency in a visual range. Besides, light emission of the multi-photon polarization laser material has extremely high polarization anisotropy, and the degree of polarization is higher than 99.9%.

The invention discloses a single-photon polarization imaging array with gathering and smoothing functions. According to the structure, polarization detection units are arranged in a two-dimensional periodic mode; each polarization detection unit comprises a single photon detector set and four gathering coupling structures in different polarization directions, wherein the polarization directions are the horizontal direction, the 45-degree right inclination direction, the vertical direction and the 45-degree left inclination direction. The gathering coupling structures are the upper metal grating layer, a transparent medium gathering layer, a metal barrier layer and a lower metal reflecting light-emitting layer according to the sequence in which incident light passes through successively. The single-photon polarization imaging array has the advantages that the three functions of polarization resolution, gathering coupling and smoothing are integrated, and the array can be highly integrated with various single-photon detectors. The huge application value is achieved in the fields such as polarization encoding and single photo polarization imaging technologies in quantum information.

Systems and methods for obtaining information on a key in the BB84 (Bennett-Brassard 1984) protocol of quantum key distribution are provided. A representative system comprises a quantum cryptographic entangling probe, comprising a single-photon source configured to produce a probe photon, a polarization filter configured to determine an initial probe photon polarization state for a set error rate induced by the quantum cryptographic entangling probe, a quantum controlled-NOT (CNOT) gate configured to provide entanglement of a signal with the probe photon polarization state and produce a gated probe photon so as to obtain information on a key, a Wollaston prism configured to separate the gated probe photon with polarization correlated to a signal measured by a receiver, and two single-photon photodetectors configured to measure the polarization state of the gated probe photon.

A device and a method for directly measuring a photon polarization density matrix relate to a technology for directly measuring a photon polarization density matrix, and are disclosed in order to solve the problem that the quantum tomography fails to provide a method for directly getting the coherence in quantum physics. A to-be-measured signal enters a first state converter. The to-be-measured signal after conversion by the first state converter enters a diagonal polarization dependent displacement crystal. The to-be-measured signal after conversion by the diagonal polarization dependent displacement crystal enters a second state converter. The to-be-measured signal after conversion by the second state converter enters an imaging system. The to-be-measured signal output by the imaging system enters a third state converter. The to-be-measured signal after conversion by the third state converter is received by a CCD camera. The beneficial effects are as follows: the measuring method only needs three times of measurement of two substrates to determine arbitrarily selected density matrix elements without considering the system dimension (d), and is a very attractive and effective method to replace the tomography to detect the potential mixed state locally.

The invention provides a photon polarization state compensation method based on complete reconstruction. A transmitting end and a receiving end encode and decode the photon polarization state by randomly using three groups of non-orthogonal polarization bases; the photon polarization state to be received in expectation is expressed by a point on the poincare sphere; the error rate of the photon polarization state to the polarization state itself is calculated when the bases are matched, the uncertainty rate of the photon polarization state to one of the groups of non-orthogonal bases is calculated when the bases are not matched, the uncertainty rate of the photon polarization state to the other one of the groups of non-orthogonal bases is further calculated when the bases are not matched, so that the complete reconstruction of the photon polarization state is realized, a polarization control apparatus is adjusted, and the photon polarization state compensation of a quantum key distribution system is realized. According to the invention, without influencing the communication efficiency and distance of the quantum key distribution system and increasing the system cost, the bad influence of trail compensation is eliminated by complete reconstruction, and the timeliness and the accuracy of real-time compensation to the two non-orthogonal photon polarization states are further improved.

The invention relates to frequency lock of a laser device in the 1529 nm optical communication wave band, in particular to a method and device for stabilizing the 1529 nm optical fiber communication laser frequency to solve the technical problem that an existing laser frequency stabilization technology for the 1529 nm optical communication wave band is affected by noise brought by frequency modulation. The method for stabilizing the 1529 nm optical fiber communication laser frequency includes the following steps of firstly, converting a bundle of 780 nm laser locked by a polarization spectrum into a sigma+ circularly polarized light, and leading the circularly polarized light to a rubidium bubble filled with rubidium 87 steam; secondly, leading a bundle of linear polarization laser outputted by a 1529 nm semiconductor laser device to the rubidium bubble; thirdly, dividing a 1529 nm laser emitted from the rubidium bubble into two bundles of light with the perpendicular polarization directions, collecting magnitude signals of the two bundles of light, converting the magnitude signals into corresponding electrical signals respectively, and subtracting one of the electric signals from the other electrical signal to obtain a two-photon polarization spectrum signal; fourthly, feeding the two-photon polarization spectrum signal back to the 1529 nm semiconductor laser device. The method and the device can be applied to the superfine spectrum field, the frequency standard field, the precision measurement field and other fields.

The invention relates to a single-photon polarization state quantum imaging system based on a DMD micromirror array. The system comprises a laser transmitting device, a single-photon preparation system, a DMD control imaging device, and an EMCCD imaging receiving system; the laser transmitting device is a semiconductor laser and is used for emitting laser beams; the single-photon preparation system is used for converting the laser emitted by the laser transmitting device into single photon pulses in different polarization states; the MD control imaging device directly acts on the single photonpulses in different polarization states and reflects the single photon pulses to the EMCCD imaging receiving system; the EMCCD imaging receiving system images the single photons in different polarization states, performs statistical analysis on detected photon information, and also obtains an image measurement error rate and imaging reliability. The system is simple in structure, convenient to operate, accurate in measurement, high in feasibility and easy to apply.

One or more embodiments relate generally to the field of photoelectron spin and, more specifically, to a method and system for creating a controllable spin-polarized electron source. One preferred embodiment of the invention generally comprises: method for creating a controllable spin-polarized electron source comprising the following steps: providing one or more materials, the one or more materials having at least one surface and a material layer adjacent to said surface, wherein said surface comprises highly spin-polarized surface electrons, wherein the direction and spin of the surface electrons are locked together; providing at least one incident light capable of stimulating photoemission of said surface electrons; wherein the photon polarization of said incident light is tunable; and inducing photoemission of the surface electron states.

A cryptography method using a quantum phenomenon, which performs a multi-staged polarization process between a transmitter and a receiver to prevent a third party from knowing the polarization value of a photon. A transmitter rotates a photon flux by arbitrary angle θ and transmits it to a receiver. The receiver rotates the received photon flux by arbitrary angle φ and transmits it to the transmitter. The transmitter rotates the received photon flux by the reverse angle −θ of an angle, by which the transmitter 10 rotated it, then rotates it by polarization corresponding to an information bit, and transmits it to the receiver which rotates the received photon flux by the reverse angle −φ of an angle, and measures the polarization of the photon flux corresponding to the information bit, and recovers the information bit transmitted by the transmitter. Cryptography information may be transmitted using a plurality of photon fluxes.

The invention relates to the technical field of quantum encryption, in particular to a quantum technology-based encryption algorithm, which comprises the following steps of: step 1, setting three groups of base vectors, step 2, generating a binary quantum sequence and a measurement base vector, and respectively representing six polarization states corresponding to the measurement base vector by utilizing three variable combinations; step 3, encrypting the information M, converting the binary quantum sequence and recoding the binary quantum sequence; 4, detecting whether the first segment of the measurement base sequence is a random number or not; step 5, when the Eve does not exist, decrypting the data; and 6, when the Eve exists, reselecting other quantum channels. The encryption algorithm has the beneficial effects that the oblique basis of photon polarization and the horizontal plane is recoded into the first segment of the binary quantum sequence, so that Bob can quickly detect whether the confidence is eavesdropped or not, the data processing amount is reduced, corresponding information is encrypted through an encryption algorithm, the eavesdropping difficulty is increased, and the security of encrypted transmission is improved.

The invention discloses a high-performance straight-waveguide-type electro-optic phase modulator and a preparation method thereof. The electro-optic phase modulator has a plate-capacitor-type structure, and comprises a single crystal which is equivalent to a dielectric layer and electrode layers on the upper and lower surfaces of the single crystal. The single crystal is a binary (1-x)Pb(Mg1 / 3Nb2 / 3)O3-xPbTiO3 system or a ternary (1-x-y)Pb(In1 / 2Nb1 / 2)O3-xPb(Mg1 / 3Nb2 / 3)O3-yPbTiO3 system. The straight-waveguide-type electro-optic phase modulator is capable of using the domain steering and the difference of birefringence of a ferroelectric, inducing the domain steering through a prefabricated electric field applied to coplanar electrodes, producing the change of the refractive index which is up to 3% in the local section, and effectively constructing a simple optical waveguide structure which is easily processed and manufactured. The high-performance straight-waveguide-type electro-optic phase modulator has the characteristics of very low half-wave voltage, low insertion loss, high bandwidth and excellent phase modulation ability. The ferroelectricity and the strong optical nonlinearity are combined, various optical information conversion devices can be designed, and the effective control of the photon polarization state, the detection of a weak signal and the generation and control of a phased array signal are realized. The high-performance straight-waveguide-type electro-optic phase modulator is suitable for the quantum secret communication technology and microwave photonics radar technology fields.

The invention discloses an automatic basic vector regulation system and an automatic basic vector regulation method for a quantum communication system. The system is mainly applied in quantum communication to realize the automatic control of basic vector regulation, and is applicable to various laser communication systems requiring basic vector regulation. A specific orthogonal two-dimensional coordinate system which is called basic vector is introduced into the system as a standard for judging photon polarization state, and moreover, the coordinate system for judging the polarization state of signal light in the whole communication system is consistent. The automatic basic vector regulation system can solve the problem that the polarization direction of the signal light in quantum communication is changed because the direction of a telescope is changed during tracking, thus ensuring that a receiving end can correctly detect the polarization state of the signal light under the specific basic vector standard and that space scale quantum communication can be freely and smoothly carried out.

The invention provides a photon polarization state compensation method based on evolutionary historical reconstruction; a novel nyquist method for performing polarization state evolution reconstruction in quantum key distribution is applied to polarization state real-time prediction and compensation, so that the precision of polarization state compensation based on the measurement result of a quantum optical signal and the capability of tracking fast polarization change are improved.

The invention discloses an accurate target material identification system. The accurate target material identification system comprises a polarized light emitting system and a polarized light detecting system. The polarized light emitting system comprises a pulse laser, an optical splitter, an emitting system and a PIN detector connected with the optical splitter, wherein the pulse laser, the optical splitter and the emitting system are sequentially arranged. The polarized light detection system comprises a receiving system, a four-way Stokes photon polarization detection system, a photon counting data acquisition system and a data processing system which are sequentially connected, wherein the PIN detector is connected with the photon counting data acquisition system, and the Stokes vector of reflected photons is calculated by using the photon count distribution measured by Gm-APD, and the purpose of target material identification is achieved through the change of the Stokes vector.

The invention relates to a superconducting nanowire-based single-photon polarization detection device and an implementation device thereof. The superconducting nanowire-based single-photon polarization detection device comprises a substrate and a pixel layer arranged on the substrate, wherein the pixel layer comprises one or more super pixel units, each super-pixel unit comprises at least four pixel units, and each pixel unit is composed of a zigzag superconducting nanowire; the angles of the superconducting nanowire structures of the pixel units in the parallel direction are different, and the polarization state of the linearly polarized light can be solved by counting the light response of the four superpixels to the polarization angle of the polarized light. Compared with an existing semiconductor polarization detection device, the superconducting nanowire structure has dual functions of a linear polarizer and a photon detector, not only integrates the advantages of a superconducting nanowire structure single photon detector, but also has the characteristics of expandable device scale, simple structure and the like, so that the superconducting nanowire-based single-photon polarization detection device is expected to be applied to the polarization detection and imaging, quantum communication, astronomical observation and the like in a weak light environment.

The disclosure provides a binary iterative clock synchronization system based on polarization entanglement GHZ state comprising a first synchronization party, a second synchronization party and an emitting party; the first synchronization party is connected with the second synchronization party through a classical channel, the emitting party is connected with the first synchronization party through a quantum channel, and the emitting party is connected with the second synchronization party through a quantum channel and a classical channel; the emitting party realizes the preparation of three-photon polarization entangled GHZ states and measures one of the photon polarization states; the first synchronization party and the second synchronization party perform measurement on the polarization states of the other two photons, and the second synchronization party and the emitting party compare the measurement results to obtain the measurement sequence information between the first synchronization party and the second synchronization party.

The invention provides a multi-user measurement equipment unrelated QKD system and method based on a GHZ entangled state. The multi-user measurement equipment unrelated QKD system comprises N + 1 senders and N measurement parties, wherein the first sender, the second sender,..., and the Nth sender are connected with each other through a classical channel, the Nth sender and the Nth measurer are connected one by one through quantum channels, and the (N + 1)th sender is connected with the first measurer, the second measurer,..., and the Nth measurer through quantum channels. And the first sender, the second sender,..., and the Nth sender send the single photon polarization state, and the (N + 1)th sender sends the GHZ entangled state. Particles prepared by the first, second,..., Nth and (N +1)th sending parties interfere with each other in the first, second,..., Nth measuring parties, Bell state measurement is carried out, and a code value is formed. According to the invention, the communication distance is greatly increased, the attack on the measurement equipment can be resisted, and the first, second,..., and Nth measurement parties in the invention can be non-trusted parties.

The invention discloses a method for setting a GHZ state generation chip based on a quantum frequency comb. The chip structurally comprises a quantum frequency comb light source and a path polarization converter, the quantum frequency comb light source comprises 2-3 independent and coherent nonlinear optical parameter conversion units capable of generating frequency comb associated photon pairs and a wavelength division multiplexing unit. The quantum frequency comb light source generates two sets of photon pairs covering all frequencies, the photon pairs are output from an upper path and a lower path respectively, two photons output from each path are paired due to energy conservation in frequency, but the upper path and the lower path correspond to two completely different pairing modes to form two items of a GHZ state, and when only one photon exists in each frequency, a frequency-marked multi-photon path coding GHZ state is obtained; and the path polarization converter transfers thepath information of the photons to the polarization degree of freedom to obtain a multi-photon polarization coding GHZ state.