14 results about "Vacuum state" patented technology

The present disclosure relates to a system and a method of performing Gaussian boson sampling via time multiplexing correlation of squeezed vacuum states for quantum information experiments. One embodiment relates to a method for performing Gaussian boson sampling comprising the steps of—generating a set of pulsed pairs of squeezed vacuum states,—performing time 2024 / 038212 multiplexed correlation of multiple of such pairs of squeezed vacuum states,—measuring, via a homodyne detection, a state from the pairs of generated squeezed vacuum states,—feed-forwarding the homodyne result of the measured states to a displacement unit,—performing displacement operations on the remaining state from the pairs of generated squeezed vacuum states, and—counting the states output from the displacement unit.

The application discloses a photon intensity control method and device of a BB84 decoy state quantum key distribution system, and relates to the technical field of quantum communication photon intensity control. The photon intensity control method comprises the following steps: detecting the photon intensity of the photon state of a first beam splitting ratio after beam splitting; determining the average photon number ratio of the photon state according to the photon intensity of the photon state and the trigger number of the photon state; determining the control signal of the photon state according to the average photon number ratio of the photon state; and controlling the photon intensity of the photon state of a second beam splitting ratio after beam splitting in response to the control signal of the photon state, so as to control the photon intensity of the photon state of the second beam splitting ratio of the BB84 decoy state quantum key distribution system. The photon intensity control method can accurately control the photon intensity of the signal state, the photon intensity of the decoy state and the photon intensity of the vacuum state, and improve the feedback control precision.

The invention belongs to the technical field of quantum radar detection, and relates to a turbulent atmosphere target detection method based on a dual-mode compressed vacuum state quantum illumination radar, and the method comprises the steps: selecting a TMSV state as an emission light field according to the working principle of the quantum illumination radar, and describing the TMSV state as a TMSV state density matrix; establishing a model for revealing a physical decoherence mechanism according to an influence mechanism of an atmospheric turbulence effect on signal mode light field propagation; in the propagation process of the signal mode light field in the turbulent atmosphere, a lost quantum state density matrix is obtained by acting a Kraus operator on the TMSV state density matrix; a density matrix of a diffused quantum state is obtained by acting a Kraus operator on the density matrix of the TMSV state; modeling a target as a beam splitter, and describing the interaction of a signal mode light field and background thermal noise at the target by using a unitary operator to detect the target; the detection error probability is reduced, and the detection sensitivity is improved.

A high-speed quantum random number generator based on a vacuum state fluctuation technology includes a laser light source (1), an unequal proportion optical splitter (2), a programmable logic device (3), n differential detectors (4), and n groups of amplifiers (5) and analog-to-digital converters (6) connected sequentially. A laser signal emitted by the laser light source (1) is divided into n first light beams and n second light beams by the unequal proportion optical splitter (2). Each of the first light beams and one corresponding second light beam are input to input ends of one of the differential detectors (4). An output end of each of the differential detectors (4) is correspondingly connected to an input end of one of the amplifiers (5). An output end of the analog-to-digital converter (6) is connected to an input end of the programmable logic device (3).

The present disclosure relates to a system and method for performing Gaussian boson sampling by time-multiple correlation of squeezed vacuum states for quantum information experiments. One embodiment relates to a method for performing Gaussian boson sampling, comprising the steps of generating a set of pulse pairs of squeezed vacuum states, performing time-multiple correlation of a plurality of such pairs of squeezed vacuum states, measuring states from the generated pairs of squeezed vacuum states by homodyne detection, feeding forward the homodyne results of the measured states to a displacement unit, performing a displacement operation on remaining states from the generated pairs of squeezed vacuum states, and counting the states output from the displacement unit.

The invention discloses a vacuum-state quantum random entropy source chip and a random number sequence generation method, and belongs to the technical field of vacuum-state quantum random entropy sources and quantum integrated chips. A monolithic integrated chip of a light source, a beam splitter module and a balanced homodyne detection module is designed, the beam splitter module is formed by connecting multiple stages of beam riffles in series, each beam riffle comprises a first port, a second port and two output ends, the first port of the first-stage beam riffle receives local oscillator laser emitted by the light source, and the second port of the second-stage beam riffle receives local oscillator laser emitted by the balanced homodyne detection module. The second port of each level of light beam riffle inputs a vacuum state, and split laser carrying a vacuum state signal output by the output end of each light beam riffle is used as an input signal of the first port of the next level of light beam riffle; in use, the multi-channel quantum random number sequence can be generated by starting the light source. The system can meet the application requirements of small size, low cost, stable performance and high reliability, has the advantages of high confidentiality, high speed, multiple channels, high integration and the like, and can meet more application scenes.

A high-speed quantum random number generator includes a laser light source, an unequal proportion optical splitter configured split a laser signal emitted by the laser light source into n first light beams and n second light beams, n differential detectors, n amplifiers, n analog-to-digital converters, and a programmable logic device. Input ends of each of the differential detectors is coupled to the unequal proportion optical splitter and configured to receive one of the first light beams and one of the second light beams. An input end of each of the amplifiers is coupled to an output end of a corresponding one of the differential detectors. An input end of each of the analog-to-digital converters is coupled to an output end of a corresponding one of the amplifiers. An output end of each of the analog-to-digital converters is connected to an input end of the programmable logic device.

The present disclosure relates to a system for forming continuous variable cluster states and quantum correlations with microwaves comprising a cryogenic chamber (161) with a cryocooler, a superconducting parametric circuit (110), SPC, comprising a resonator (111), a pumping circuitry (140) arrange to pump said SPC (110) with three or more microwave signals (260) to form a pump field (280) in the resonator (111), control circuitry (180) arranged to control the pumping circuitry (140). The cryocooler is arranged to prepare a vacuum state inside the cryogenic chamber (161), and the control circuitry (180) is arranged to control the pumping circuitry (140) to pump the SPC (110) with microwave signals (260). The pump field in the resonator (111) mixes with frequency components of the quantum fluctuations (240) at the vacuum level to generate quadrature-squeezed states of microwave electromagnetic waves (290) which form a continuous variable cluster state.

The application provides a kind of quantum bit fast reading method based on resonant cavity field strength strict control, belong to quantum computing and quantum information processing technical field, this method includes: extracting the readout resonant cavity coupled with quantum bit, obtains the key parameter of readout resonant cavity;Set driving signal frequency and calculate the detuning of ground state and excited state;Design pulse-maintain two-section type driving signal, determine the matching relationship of two pulse amplitudes, generate two-section type microwave driving signal;Two-section type microwave driving signal is applied to readout resonant cavity, carry out the fast response of resonant cavity field strength;Establish strict stable condition, so that cavity field reaches stable value strictly;Based on the coupling effect of superconducting quantum bit and readout resonant cavity, determine quantum bit state through dispersion model;After reading, quickly empty the photon in cavity to vacuum state, realize fast reset.The application realizes resonant cavity field strength fast response and reset through field strength strict control, realizes the fast, accurate reading of quantum bit.

This invention relates to the field of quantum communication technology and discloses an anti-interference quantum key distribution protocol optimization method, comprising: acquiring the single-photon counter count statistics output by the measurement end during the key screening stage, including signal state, decoy state, and vacuum state count values; calculating the instantaneous variance of the vacuum state count value and determining a counting correction parameter based on the ratio of the variance to the signal state count value; using the parameter to correct the gain deviation of the single-photon counter count statistics; extracting the polarization deviation feature vector from the corrected statistics and determining the bit offset parameter; and performing bit-level logic remapping on the key screening sequence based on the bit offset parameter to compensate for channel disturbances when the polarization control voltage at the measurement end is constant. This invention converts the basis vector deflection into an address offset through protocol layer logic mapping, eliminates the occupation of the link by hardware calibration, ensures the continuity of key generation under environmental disturbances, avoids background noise introduced by strong light pilots, and improves quantum key distribution efficiency.

The invention provides a quick quantum bit reading method based on strict control of resonant cavity field intensity, and belongs to the technical field of quantum calculation and quantum information processing.The method comprises the steps that a reading resonant cavity coupled with quantum bits is extracted, and key parameters of the reading resonant cavity are obtained; setting a driving signal frequency and calculating detuning amounts of a ground state and an excitation state; designing a pulse-maintaining two-section type driving signal, determining a matching relation of two sections of pulse amplitudes, and generating a two-section type microwave driving signal; the two-section type microwave driving signal is applied to the read-out resonant cavity, and quick response of the field intensity of the resonant cavity is carried out; a strict stable condition is established, so that the cavity field strictly reaches a stable value; based on the coupling effect of the superconducting quantum bit and the read-out resonant cavity, the quantum bit state is judged through a dispersion model; after reading is completed, photons in the cavity are rapidly emptied to a vacuum state, and rapid reset is achieved. Rapid response and reset of the field intensity of the resonant cavity are realized through strict control of the field intensity, and rapid and accurate reading of quantum bits is realized.

The application discloses a kind of based on the method and system of quantum random number generation of decoy state of ubiquitous light source, the method can be applied in quantum random number generator system not depending on specific light source distribution.This method is prepared by party Alice, and the received optical pulse is randomly modulated into signal state, decoy state and vacuum state, then the modulated optical pulse is randomly prepared into one of four different encoding states, and is sent to measuring party Bob;Measuring party Bob randomly selects base vector to project the encoding state sent to carry out measurement, and obtains output result;Gain under corresponding optical pulse intensity is calculated, and channel parameters and randomness size are estimated based on the calculated gain using decoy state method;According to the randomness size, random number is extracted in measurement result.The application does not depend on specific light source distribution, and has universality.

There is provided a method for resetting an arbitrary state, hosted in a quantum system, to the vacuum Fock state or a coherent state, wherein the quantum system comprises: (I) at least one resonant portion configured to have a first mode having a first resonant frequency and wherein the arbitrary state is hosted in the first mode, (II) a non-linear element coupled to the at least one resonant portion so as to non-linearly couple to the first mode, and (III) one or more signal generator(s) coupled to the at least one resonant portion and / or to the non-linear element and configured to input control signals to physically stabilize a cat qubit subspace in the first mode having a cat phase angle. The method comprises: (i) physically stabilizing for a first period of time, with the one or more signal generator(s), a first cat qubit subspace having a first cat phase angle and first cat size ΙαΙ2, wherein α is a first amplitude which is the amplitude of the superposed coherent states Ι ± α > defining the first cat qubit subspace (702); (ii) after the first period of time, physically performing for a second period of time, with the one or more signal generator(s), a first parallel displacement drive by inputting electromagnetic radiation having a first phase substantially equal with the first cat phase angle, a frequency substantially equal to the first resonant frequency, and a first displacement amplitude greater than or equal to the first amplitude (704); (iii) after the second period of time, physically stabilizing for a third period of time, with the one or more signal generator(s), a second cat qubit subspace having a second cat phase angle which is substantially equal to the first cat phase angle and second cat size ΙβΙ2, wherein β is a second amplitude which is the amplitude of the superposed coherent states Ι ± β > defining the first cat qubit subspace, such that a coherent state Ιβ> with the second amplitude β is stabilized in the first mode (706). There is also provided a corresponding quantum processor, a computer program product, and a computer-readable medium.