18 results about "Density matrix" patented technology

The invention discloses a quantum phase-locked detection method based on entanglement enhancement, and the method comprises the steps: encoding quantum bits in a ground state and an excited state, and preparing the quantum bits into an initialized quantum state; loading a periodic multi-pulse sequence to act on the quantum bits; and loading a carrier pulse resonating with the ground state and the excited state, detecting the final quantum state of the quantum bit, and comparing curves of each component of the measurement density matrix and the theoretical density matrix changing along with the pulse time interval of the periodic multi-pulse sequence to obtain the half cycle and the amplitude of the sine wave to be measured. According to the method, measurement noise under the condition that the rotation angle and the detuning error exist can be effectively restrained, high measurement precision is kept under the condition that the rotation angle and the detuning error exist, and the robustness enables the method to be more reliable in practical application.

The application discloses a quantum phase-locked detection method based on entanglement enhancement, encodes quantum bits in a ground state and an excited state, and prepares the quantum bits as initial quantum states; a periodic multi-pulse sequence is loaded on the quantum bits; a carrier wave pulse resonating with the ground state and the excited state is loaded; a final quantum state of the quantum bits is detected; curves of each component of a measured density matrix and a theoretical density matrix changing with a pulse time interval of the periodic multi-pulse sequence are compared; and a half period and an amplitude of a to-be-measured sinusoidal wave are obtained. The application can effectively suppress measurement noise under the condition of existing rotation angles and detuning errors, and can maintain high measurement precision under the condition of existing rotation angles and detuning errors. The robustness makes the application more reliable in practical application.

The application discloses a kind of target system energy calculation method, device and storage medium, method includes: first according to the electronic integration in the target system to be simulated and initial density matrix determines Fock matrix, then according to Fock matrix, iteration operation to initial density matrix is executed, until the difference of density matrix obtained in front and back two times meets preset accuracy when iteration process appears, current density matrix obtained in back is as target density matrix, finally based on the energy of the target system to be simulated is calculated based on the target density matrix obtained, it is determined by target density matrix, and the target system energy is calculated, so that the calculation accuracy of target system energy is improved, applicable to the quantum calculation simulation of complex system, further promote the development of quantum chemistry simulation application.

The invention relates to the technical field of bridge construction safety monitoring, and discloses a road and bridge construction multi-sensor data fusion safety early warning system. The system comprises a data preprocessing and quantum state characterization module, a heterogeneous tensor field construction and quantum correlation analysis module, a quantum topological structure analysis and risk area identification module, a non-equilibrium tensor field evolution and risk early warning module and an early warning output and visualization module. The method comprises the following steps: uniformly mapping multi-source heterogeneous sensor data into a density matrix in a high-dimensional Hilbert space, calculating quantum correlation degree quantity among the data to construct a multi-dimensional heterogeneous tensor field and a quantum correlation topological graph, and identifying a risk area and a propagation path by calculating topological invariants of the topological graph. And the risk critical point is predicted by monitoring entropy generation rate evolution of the tensor field. According to the method, the heterogeneous data can be deeply fused, the weak links of the structure can be identified from the system level, the risk evolution trend can be prospectively pre-judged, and the early-stage and interpretable early warning of the construction risk can be realized.

The invention relates to the field of visual detection, discloses a multispectral fusion dynamic defect visual detection method and system, and solves the defects in the prior art through quantization spectrum fusion, curvature manifold embedding, soliton packet generation and topological mark extraction. Comprising the following steps: converting multispectral data into a Compton wavelength ratio tensor, eliminating physical characteristics of a sensor through Planck scale normalization, establishing a defect quantum tunneling probability model based on a Fermi golden rule, quantifying an electron transition behavior of a defect tip, embedding defect probability distribution into a Riemannian manifold, and establishing a defect quantum tunneling probability model based on the Riemannian manifold. And a curvature scalar invariant field is extracted by using conformal mapping, topological feature continuous tracking of defect evolution is realized, and a defect life cycle is analyzed and predicted based on a quantum state density matrix and a de-coherence process. The method has the characteristics of high sensitivity, strong anti-interference capability and accurate prediction, and can be widely applied to the fields of high-end equipment manufacturing, material science, industrial nondestructive testing and the like.

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.

The present application relates to the technical field of quantum state preparation, and particularly relates to a multi-quantum state preparation method, comprising: S1, randomly initializing an Ansatz circuit parameter; S2, inputting an initial quantum state into a variational quantum circuit under a current circuit parameter configuration to obtain a corresponding output state density matrix; S3, calculating a loss value between the output state density matrix and a target state according to the output state density matrix, feeding back the loss value to a classical optimizer, updating the Ansatz circuit parameter, returning to S2 until a preset condition is reached, and obtaining a trained variational quantum circuit; and S4, using the trained variational quantum circuit to realize preparation of multiple groups of target quantum states. The present application learns and approximates to prepare any target quantum state by constructing a quantum neural network structure with expression capability.

The application discloses a method for calculating an interplanetary cross scaling coefficient according to particle phase space density correlation characteristics, comprising the following steps: obtaining particle flux sequences of a standard A star and a to-be-scaled B star; under a T89c external magnetic field model, respectively calculating a modified third adiabatic invariant and a second adiabatic invariant of the A star and the B star, and calculating a local magnetic field intensity; performing uniform grid division on time and the third adiabatic invariant, and performing logarithmic uniform grid division on the first adiabatic invariant and the second adiabatic invariant; obtaining a local pitch angle and energy in the grid; screening out points with data in the same grid to obtain particle phase space densities of the A star and the B star respectively; calculating a particle phase space density average in the grid; respectively establishing particle phase space density matrices of the A star and the B star; screening out points with data in the same grid of the particle phase space density matrices of the two stars to obtain a cross scaling coefficient of the B star.

The invention belongs to the technical field of quantum information, and particularly relates to a quantum key distribution method based on a density matrix equivalence thought, and the method comprises the following steps: S1, preparing a quantum state; step S2, quantum channel transmission; s3, comparing basis vectors; s4, estimating the bit error rate; step S5, parameter evaluation; and S6, error correction and confidentiality amplification are carried out to obtain a security key. According to the invention, the cost and complexity of the QKD system can be reduced without influencing the code rate only by performing simple statistical calculation on the unmatched basis vectors and without modifying the quantum state preparation and measurement device.

The invention relates to the technical field of quantum state preparation, in particular to a multi-quantum state preparation method, which comprises the following steps: S1, randomly initializing Ansatz circuit parameters; s2, inputting the initial quantum state into a variable component sub-circuit under the current circuit parameter configuration, and obtaining a corresponding output state density matrix; s3, calculating a loss value with a target state according to the output state density matrix, feeding back the loss value to a classic optimizer, updating the Ansatz circuit parameter, returning to S2 until a preset condition is reached, and obtaining a trained variable component sub-circuit; and S4, realizing preparation of multiple groups of target quantum states by using the trained variable component sub-circuit. According to the method, any target quantum state is learned and approximately prepared by constructing a quantum neural network structure with expression ability.

The application discloses a kind of main distribution network power flow model no solution traceability and correction method, it is related to power system dispatching technical field, including, acquisition real-time measurement data pre-processing, obtain quantum noise intensity coefficient;Quantum state density matrix is generated based on quantum noise intensity coefficient, and quantum fidelity is obtained by characteristic decomposition mapping;Based on quantum fidelity, the minimum eigenvalue is extracted, and the fault node coordinates are located by no solution traceability mapping, and the fault severity index is obtained by negative exponential mapping;Based on fault severity index, no solution traceability grade is divided, and fault scene is output;Based on fault scene, the set of power flow inversion control instructions is obtained, and the power flow no solution risk early warning value is corrected.The quantum fidelity mapping accurately locates the power grid fault source, eradicates the main distribution network model no solution problem, promotes the landing of quantum sensing industry and improves the fault response speed.

The present invention provides a method and apparatus for obtaining the steady state of an open physical system. The method comprises: determining the target quantum mixed state based on the spectral decomposition of the density matrix of the target quantum mixed state, using the evolution of a d-dimensional quantum pure state with n qubits in a quantum circuit and the quantum state after intermediate measurements, so that the target quantum mixed state has initialized circuit parameters; constructing a corresponding loss function based on selected observables, and calculating the loss function and its gradient using quantum shadow tomography; and adjusting the circuit parameters of the target quantum mixed state using a gradient descent method until the loss function is minimized, thereby obtaining the steady state. This method significantly reduces the number of qubits required for calculation, making it easier to implement under current technical conditions and having broad application prospects.

The application discloses a two-bit and three-bit unknown state entanglement determination method based on a variational quantum circuit, and comprises the following steps: generating quantum states of a plurality of known state labels based on uniform sampling of a random matrix to obtain a quantum state data set containing a two-bit data set and a three-bit data set; extracting observable operator expectation values from the quantum state data set to generate a classical feature vector; encoding the classical feature vector to an initial quantum state through a parameterized quantum gate; constructing a variational quantum circuit, and making the initial quantum state evolve through the variational quantum circuit to obtain an output state; constructing an objective function based on quantum measurement results of the output state, and outputting an entanglement determination result of the quantum state data according to the objective function value. Compared with a quantum state tomography method which depends on complete density matrix reconstruction, the method only uses observable operator expectation values highly related to entanglement determination as input, and thus significantly reduces measurement resource consumption and classical post-processing burden.

This invention discloses a method and system for hydrological uncertainty analysis based on probability density envelopes, relating to the field of hydrology and water resources technology. The method includes: collecting time series data of hydrological elements and preprocessing them; generating a uniform grid and performing kernel density estimation at the grid points to obtain density estimates; resampling each series to obtain the density matrix of the samples; calculating the standard error of the grid points; constructing candidate subsets, prioritizing the minimization of the probability density envelope area and minimizing the difference between upper and lower overprobabilities as secondary objectives, and optimizing the selection of the optimal multiplier; using the optimal multiplier to calculate the lower and upper probability density envelopes at the grid points and calculating the overprobabilities; extracting feature parameters; and comparing and analyzing the uncertainties of hydrological elements at different stations based on the feature parameters. This invention does not require a pre-defined distribution, can adaptively construct the minimum area simultaneous confidence band, and provides multi-dimensional uncertainty indicators, providing a scientific basis for watershed hydrological analysis and risk management.

This application proposes a quantum state tomography method, apparatus, and storage medium. The quantum state tomography method includes: receiving quantum system specifications and measurement constraints; preparing multiple quantum state replicas based on the quantum system specifications and measurement constraints; analyzing the multiple quantum state replicas based on Hamiltonian evolution to obtain a manifold of a predetermined quantum state; selecting an optimal measurement basis according to the manifold of the predetermined quantum state; acquiring measurement data of the multiple quantum state replicas under the optimal measurement basis to form a compressed measurement set; and generating a compressed measurement protocol based on the compressed measurement set, including: selecting a preset reconstruction algorithm and reconstructing the quantum state density matrix based on the compressed measurement set and the preset reconstruction algorithm. Based on this, this application can exponentially reduce the amount of measurement data, achieve complete state reconstruction of large-scale quantum systems, and ensure reconstruction fidelity.

The application discloses a pseudo-pure state preparation method and device based on radio frequency field inhomogeneity. The pseudo-pure state preparation method comprises the following steps: performing a first unitary operation on a thermal equilibrium state of a nuclear magnetic resonance sample to obtain a first quantum state; performing a second unitary operation on the first quantum state, so that diagonal elements corresponding to nuclear spin polarization components in a density matrix of the first quantum state are rotated to a preset direction, and off-diagonal elements corresponding to nuclear spin polarization components are rotated to a direction perpendicular to the preset direction, to obtain a second quantum state; applying a radio frequency field with predetermined parameters to the second quantum state by using a radio frequency coil to perform a non-unitary operation, to obtain a third quantum state; and performing a third unitary operation on the third quantum state to rotate nuclear spin polarization components in the third quantum state to an initial direction, to obtain a pseudo-pure state of the nuclear magnetic resonance sample. The method does not need to use a gradient field, so that the preparation difficulty is reduced, and the preparation time is shortened.

The application discloses a state tomography method and system for path-spin-orbit angular momentum-classical inseparable states. The method and system of the application comprise an amplitude measurement part and a phase identification part. The amplitude measurement part adopts each orthogonal basis projected to a Hilbert space by an optical stop, a circularly polarized analyzer, a spiral phase, etc., combines a surface array detector to receive a far-field diffraction light field distribution, and calculates a relative amplitude through a gray scale algorithm; the phase measurement part adopts a focusing lens to make different path beams in a to-be-measured light field interfere, inputs a two-dimensional distribution of a light field on an interference surface into a convolutional neural network built by the application, and directly obtains a phase difference between each path degree of freedom. Thus, complex coefficients of each orthogonal basis of the to-be-measured light field can be measured, a density matrix reconstruction is completed, and a state tomography result is obtained. The working principle of the application is completely developed according to the definition of classical inseparable state light fields of quantum-like states, the system structure is simple, the operation is simple, and the measurement precision is high.

The application discloses a quantum physics twin method and system, the method comprises the following steps: measuring a completely closed microcosmic dynamics system to be researched, obtaining a digitized initial state of the microcosmic dynamics system described by a density matrix; for a Markov approximation case, adopting a lindblad master equation to describe evolution of the microcosmic dynamics system based on the initial state, obtaining a result state of the microcosmic dynamics system; and applying the initial state and the result state. The application proposes a quantum physics twin system corresponding to a microcosmic system, and the idea of twinning is used to research dynamic processes in microcosmic systems such as quantum optics, quantum biology and quantum statistical mechanics in a digital world, the microcosmic system is researched as a digital model, and application of the microcosmic system is considered.