88 results about "Quantum noise" patented technology

A quantum noise random number generator system that employs quantum noise from an optical homodyne detection apparatus is disclosed. The system utilizes the quantum noise generated by splitting a laser light signal using a beamsplitter having four ports, one of which receives one of which is receives the laser light signal, one of which is connected to vacuum, and two of which are optically coupled to photodetectors. Processing electronics process the difference signal derived from subtracting the two photodetector signals to create a random number sequence. Because the difference signal associated with the two photodetectors is truly random, the system is a true random number generator.

The invention provides a bivariate nonlocal average filtering de-noising method for an X-ray image. The method is characterized by comprising the following steps: 1) a selecting method of a fuzzy de-noising window; and 2) a bivariate fuzzy adaptive nonlocal average filtering algorithm. The method has the beneficial effects that in order to preferably remove the influence caused by the unknown quantum noise existing in an industrial X-ray scan image, the invention provides the bivariate nonlocal fuzzy adaptive non-linear average filtering de-noising method for the X-ray image, in the method, a quantum noise model which is hard to process is converted into a common white gaussian noise model, the size of a window of a filter is selected by virtue of fuzzy computation, and a relevant weight matrix enabling an error function to be minimum is searched. A particle swarm optimization filtering parameter is introduced in the method, so that the weight matrix can be locally rebuilt, the influence of the local relevancy on the sample data can be reduced, the algorithm convergence rate can be improved, and the de-noising speed and precision for the industrial X-ray scan image can be improved, so that the method is suitable for processing the X-ray scan image with an uncertain noise model.

The invention discloses a quantum key agreement protocol based on GHZ state, comprising the following steps that: step 1, Alice and Bob randomly generate respective classical keys; step 2, Alice prepares the GHZ state and divides all particles into sequences, inserts decoy photons into one of the sequences and then transmits the sequence to Bob; step 3, Bob measures the decoy photons, Alice calculates an error rate, if the error rate is low, a step 4 is executed, otherwise, the step 2 is executed again; step 4, Alice and Bob respectively perform measurement and obtain the measurement result of each other; step 5, Alice executes unitary transformation and obtains a new sequence, and Alice transits the sequence with the inserted decoy photons to Bob; step 6, Bob measures the decoy photons, and Alice calculates the error rate, if the error rate is low, a step 7 is executed, and otherwise, the step 2 is executed again; step 7, Alice calculates a shared key of both sides; step 8, Bob generates the shared key. The quantum key agreement protocol based on GHZ state can resist participant attack, outside attack and Trojan horse attack. The quantum key agreement protocol based on GHZ state is safe in both a noiseless quantum channel and a quantum noisy channel. Moreover, quantum bit efficiency of the quantum key agreement protocol based on GHZ state is higher than the existing protocols.

The invention belongs to the field of the secret communication, and provides the chaotic signal production method and device based on the uncertainty quantum noise. The method comprises the followingsteps: S1, preparing a chaotic light source, a slave laser and a signal laser; S2, injecting the chaotic light field into the slave laser, observing an output light field of the slave laser through aspectrum analyzer, and regulating the intensity and the polarization state of the chaotic light field injected into the slave laser until the output light field of the slave laser is the chaotic lightfield; S3, enabling the light emitted from the signal laser to be incident to a balance homodyne detection system to produce the quantum noise signal, performing frequency mixing on the signal and the radio frequency signal, injecting into a modulation port of the slave laser after passing through the low-pass filter, modulating the slave laser, thereby enabling the output light field of the slave laser to be the chaotic signal with the uncertainty. The delay feature of the chaotic signal can be inhibited, and the method can be extensively applied to the chaotic signal production field.

Structural noise is accurately removed by a radiographic image correcting apparatus. A correction image data set, generated from a reference image data set obtained from a stimulable phosphor sheet onto which radiation has been uniformly irradiated, that includes at least four times the amount of structural noise compared to quantum noise, is recorded in a memory means. A correcting means corrects a radiographic image data set, employing the correction image data set recorded in the memory means.

The invention relates to a high-speed true random quantum number generating method, in particular to a method for producing random quantum number at high speed based on vacuum state quantum fluctuation. The problem that the production speed of an existing vacuum random quantum number generator is lower is solved. According to the specific scheme, the high-speed true random quantum number generating method mainly comprises the following steps that the translation effect of Gaussian distribution is firstly exerted to a vacuum state in a phase space, amplification of vacuum-state orthogonal amplitude component noise in the phase space is achieved, and the entropy content introduced by quantum noise in a system is increased; the true random bits which can be extracted in data postprocessing are increased; the background light of a homodyne detection system is strengthened, the sensitivity of the detection system to vacuum noise is improved, and a vacuum noise measurement value is amplified, so that the framing amount of vacuum noise statistics, namely sampling quantization bits are remarkably increased. By adopting the method, the vacuum random quantum number generating rate is effectively improved, and a new means is provided for manufacturing of high-speed random quantum number generators.

The invention discloses a four-particle x state-based two-party quantum key agreement protocol. The protocol includes following steps that: step 1, Alice and Bob negotiate on quantum-state codes; step 2, Alice prepares n x-state|x<00>>ABCD, and divides all the particles into four ordered sequences, and selects out 2m decoy photons and inserts the decoy photons into the sequences and transmits the sequences to Bob; step 3, Bob measures corresponding decoy photons with a correct measurement base, and informs Alice of measurement results; Alice compares the measurement results and the initial states of the decoy photons, and calculates an error rate, and executes step 4 if the error rate is low, otherwise, executes step 2; and step 4, Alice performs Bell measurement on the particles, Bob executes Z convolution Z-base measurement on the sequences, and Alice and Bob both obtain a shared key. The protocol of the invention can resist existing participant attacks, external attacks and Troy Trojan horse attacks; and the protocol is safe in a noise-free quantum channel and a quantum noise channel. The quantum bit efficiency of the protocol of the invention is higher than that of an existing secure multi-particle entangled state-based quantum key agreement protocol.

The invention relates to a passive mode-locked fiber laser device which includes a laser pumping source and a unidirectional annular resonant cavity. The unidirectional annular resonant cavity includes a wavelength division multiplexer, an Er doped fiber, a first optical-fiber collimator, a second optical-fiber collimator, a first 1/4 glass slide, a second 1/4 glass slide, a photoisolator, a bandpass filter, a polarization beam splitter and a 1/2 glass slide. The passive mode-locked fiber laser adopts nonlinear polarization rotation mode locking and utilizes the highly doped optical fiber as a gain medium so that the length of a laser cavity is reduced and the repeating frequency of the laser device is increased. Through introduction of the bandpass filter into the laser cavity, stray components and noises in the cavity are filtered so that clock jitter resulted from quantum noises is reduced. Through management of chromatic dispersion of the laser cavity, narrower pulses can be generated and wider frequency spectrum can also be obtained and intensity noises of the laser device are also reduced so that the passive mode-locked laser device is widely applicable to the field of optical-analog-digital system (OAD).

The invention provides a low-frequency balanced zero beat photodetector, which can be used for detecting quantum noises of a laser at the frequency of 50Hz-200kHz and measuring the compression noise spectrum of a non-classical light field in this band. The photodetector comprises a first PIN photodiode (1) and a second PIN photodiode (2) which are of high quantum efficiency, an AC coupling capacitor (3), a low-frequency transimpedance amplifying circuit (4), a DC sampling resistor (5) and a DC same direction proportion amplifying circuit (6). The AC output of the photodetector has the advantages of high gain, low noise, high common mode rejection ratio and so forth, and the photodetector also has a DC output and can monitor the change in the light intensity.

The invention discloses a laser Doppler velocity-measuring system with all-optical fiber light-frequency modulation. The system comprises a laser emission unit, a transceiving isolator, a laser lens, a beam combiner, a receiving detector and a computation unit, and the all optical functional units or devices are connected mutually by optical fibers. By using the system, the detection sensitivity of a laser Doppler velocity-measuring technology reaches quantum noise theory limit, and an optical system of the laser Doppler velocity-measuring technology is upgraded completely. A laser Doppler velocity-measuring meter using a new technology has the advantages that the power consumption is lower, the volume is smaller, the weight is lighter, the structure layout is more reasonable, the construction is more convenient, a transmitting lens and a receiving lens become one, no sensitiveness to impact vibration and high-low temperature changes exists, and requirement for cleanness degree of environment is low.

The present invention discloses a two-party quantum key negotiation protocol based on a three-particle GHZ state, comprising the following steps: step 1: Alice and Bob negotiate codes of quantum states; step 2: Alice prepares n+q GHZ states and divides all the particles into sequences; Alice sends a sequence SC to Bob; step 3: Bob selects and measures q sample particle(s); Alice selects measurement bases to measure corresponding particles; Bob calculates an error rate; and if the error rate is low, step 4 is performed, otherwise step 2 is performed; step 4: Alice performs a Bell measurement on two particles with the same sequence number in the sequences; Bob performs X-base measurement on the particles in the sequences; and Alice and Bob respectively obtain the same shared key according to measurement results and the codes of the quantum states. According to the present invention, the two-party quantum key negotiation protocol can resist existing participant attacks and external attacks as well as Trojan horse attacks, is safe in noiseless quantum channels and quantum noise channels, and can achieve a relatively high quantum bit efficiency.

A device for the non-contacting measurement of an object to be measured, particularly for distance and/or vibration measurement, has at least one laser light source, optical devices for splitting the light into object light (4) and reference light (5) for interacting with the object to be measured and for superimposing object light and reference light following the interaction of the object light with the object to be measured, preferably a frequency shift device in the form of a Bragg cell for producing a frequency shift between the object light and the reference light and a detecting device (15) for converting reference light and object light into electrical signals suitable for further processing. The detecting device has at least two series-connected optoelectronic transducers in the form of photodiodes (30, 31). Between the transducers is located a tap (32) for tapping a difference signal which, for further processing, is supplied to a transimpedance circuit (33) associated with one of the transducers. Thus, there is a subtraction of photodiode currents prior to processing in an amplifier circuit in a balanced detection arrangement. This inexpensively permits measurements at high reference light power with resolutions in the quantum noise limit range.

The invention provides a Y-00 quantum noise stream encryption transmission method with a low bit error rate. The method comprises the steps that a transmitting end carries out the forward error correction coding of an information sequence modulated by BPSK through a generation matrix of a low-density parity check code, and obtains a coded information sequence; the sending end performs Y-00 encryption on bits in the coded information sequence bit by bit through the base sequence to obtain a plurality of encrypted coded information sequences; the sending end performs QAM modulation on the plurality of encrypted coded information sequences; the sending end performs OFDM modulation and parallel-serial conversion on each orthogonal subcarrier and transmits the orthogonal subcarriers; a receiving end receives the signals, and performs serial-parallel conversion and OFDM demodulation; the receiving end demodulates the plurality of orthogonal subcarriers QAM to obtain a plurality of encryptedcoded information sequences; the receiving end performs Y-00 decryption on the plurality of encrypted coded information sequences through the base sequence to obtain an information sequence subjectedto BPSK modulation; and the receiving end performs iterative computation through an LDPC FEC decoder to obtain an information sequence to be transmitted.

The invention relates to the field of squeezed state optical field quantum noise measurement. A low-frequency low-noise balanced homodyne detector includes a differential circuit composed of two photodiodes, a bootstrapping current-voltage conversion circuit composed of two bumpers and a trans-impedance operation amplifier (5), and an AC and a DC output circuit composed of a first capacitor (6) and a first resistor (7) separately. According to the invention, through quantitative analysis of input current total noise of the low-frequency low-noise balanced homodyne detector in a low frequency band and since a sampling resistor in a traditional detector is removed and the bootstrapping current-voltage converter is adopted, the electronic noise of the low-frequency low-noise balanced homodynedetector within a frequency of 20 Hz to 200kHz is reduced substantially and requirements for high gain, high common-mode rejection ratio, simple structure and low cost are met.

The invention relates to a quantum noise stream encryption system based on a one-dimensional chaotic sequence and a coding and decoding method. The method comprises the following steps: obtaining a binary chaotic sequence; respectively carrying out one-by-one exclusive-or operation on the binary chaotic sequence and the I/Q component of the binary plaintext information, and mapping to obtain a low-order QAM ciphertext; increasing the digits of the low-order QAM ciphertext by using a QNSC technology, and mapping to obtain a high-order QAM ciphertext; performing offline digital signal processing on the high-order QAM ciphertext, and transmitting the high-order QAM ciphertext to a receiving end through a first optical fiber channel. The coding and decoding method is improved, the effect of a state base during decoding is expanded, the bit error rate is reduced, and the safety is high.

The present invention presents a device and method for managing the performance of a quantum noise-based random number generator, the device ensuring the performance stability of a random number generator on the basis of an output value for each pixel, which is outputted in correspondence to an optical strength value of an optical signal emitted from a light source and inputted into each pixel, so as to be capable of outputting, within a certain range regardless of devices, a value of an entropic signal outputted from an image sensor, thereby enabling sufficient randomness to be continuously maintained while minimizing deviation between pixels.

The invention relates to chaotic laser, in particular to a method and a device for suppressing chaotic delay by using broadband spontaneous emission quantum noise, which solves the problem that the existing chaotic signal generation system has delay characteristics. The device for suppressing chaotic delay by using broadband spontaneous emission quantum noise comprises a broadband spontaneous emission quantum noise system and a continuous chaotic laser signal generation system to construct a broadband spontaneous emission quantum noise preparation system. Chaos is modulated by generating continuous chaotic laser signals and broadband spontaneous emission quantum noise. The broadband spontaneous emission quantum noise adopted by the invention can provide uncertain initial values for chaoticsignals, so that the final chaotic signals cannot be predicted and become chaotic signals with uncertainty, chaotic laser delay characteristics can thus be effectively suppressed, and the method andthe device can be used in the field of secure communication.

The embodiment of the invention provides a method for determining quantum circuit noise and a quantum state estimation method, and the method comprises the steps: carrying out N1 rounds of random measurement for a plurality of quantum units whose initial states are ground states, wherein each round of random measurement comprises the steps: inputting the plurality of quantum units into a pre-established random quantum circuit, measuring the plurality of quantum units evolved by the random quantum circuit, determining a first measurement result corresponding to the round of random measurement, and determining a random unitary matrix corresponding to the round of random measurement according to the state of the random quantum circuit; and determining noise parameters of the random quantum circuit based on N1 first measurement results corresponding to N1 rounds of random measurement and N1 random unitary matrixes. And determining a plurality of random samples of the to-be-measured state of the plurality of quantum units based on the noise parameter and N2 second measurement results and N2 random unitary matrixes obtained by random measurement of N2 rounds on the plurality of quantum units of the to-be-measured state.