A practical anti-noise quantum correlation assisted multi-user entanglement distribution quantum network

Abstract

The application discloses a practical anti-noise quantum correlation auxiliary multi-user entanglement distribution quantum network, which comprises a network user shared entangled photon pair source, a wavelength distribution module, an optical fiber link and a polarization analysis module. The network user shared entangled photon pair source introduces frequency-related quantum correlation in a polarization entangled photon pair, and extracts entangled photons from noise through frequency correlation. The wavelength distribution module selects different frequency entangled photon pairs according to the frequency degree of freedom, and sends the entangled photon pairs to a specific user pair through a noise-containing optical fiber link, so that each user randomly selects a measurement base vector, and polarization encoding and decoding are performed by using the polarization analysis module to extract signal photons from noise photons, and a single-photon detector is used to detect photons to establish a secure key, and information is securely shared. The application can establish a secure key under limited key analysis, and realizes information security sharing among users.

Description

Technical Field

[0001] This invention belongs to the fields of quantum information, quantum communication, optical quantum technology, and integrated optical quantum technology, and specifically relates to a practical noise-resistant quantum correlation-assisted multi-user entanglement distribution quantum network. Background Technology

[0002] The properties of quantum entanglement and superposition in quantum mechanics guarantee that quantum information processing (such as quantum computing, quantum communication, and quantum metrology) is inherently more powerful than classical information processing. As carriers of quantum information, photons can be encoded in various degrees of freedom, including polarization, path, frequency, and orbital angular momentum. In particular, the frequency degree of freedom of photons is highly attractive for their compatibility with existing fiber optic infrastructure. Multiplexing of frequency degrees of freedom can not only improve data transmission rates in classical communication but also provide extensive connectivity for quantum networks. To date, various topologies of quantum networks with trusted relays or active / passive routing have been developed. Among these, quantum network schemes based on fully and simultaneously connected entangled networks shared among each user show potential promise due to their scalability and integrability.

[0003] However, most of these demonstrations are achieved by allocating additional dark fiber links to protect the fragile quantum states. Distributing entangled photons in real-world environments inevitably introduces noise from classical light. The interaction of this noise with the quantum states ultimately reduces channel capacity, becoming a limiting factor for key rates and distances in quantum communication, thus hindering the technology's scaling to larger scales. Therefore, constructing scalable and robust communication links between multiple users within existing fiber optic networks is one of the core tasks for realizing large-scale quantum communication. Summary of the Invention

[0004] Technical problem solved: This invention provides a practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network. It proposes introducing frequency-dependent quantum correlations into polarization-entangled photon pairs, thereby significantly enhancing the noise tolerance of entangled photons. Simultaneously, by designing and fabricating semiconductor chips with high mode overlap, broadband polarization entanglement is directly generated, and quantum correlations are used to significantly improve the noise tolerance of entangled photons in fiber optic links. Furthermore, time-division multiplexing is used to reduce detector resource consumption, thus realizing a practical noise-resistant multi-user entangled distribution quantum network. A secure key is established under finite key analysis, enabling secure information sharing among users.

[0005] Technical solution:

[0006] A practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network, the multi-user entangled distribution quantum network including a source of entangled photon pairs shared by network users, a wavelength allocation module, an optical fiber link, and a polarization analysis module;

[0007] The network user-shared entangled photon pair source introduces frequency-dependent quantum correlation in polarization-entangled photon pairs, and extracts entangled photons from noise through frequency correlation;

[0008] The wavelength allocation module selects entangled photon pairs of different frequencies according to the frequency degrees of freedom and sends them to specific user pairs through a noisy fiber optic link. Each user randomly selects a measurement basis vector, uses a polarization analysis module for polarization encoding and decoding, extracts signal photons from noisy photons, and uses a single-photon detector to detect photons to establish a security key for secure information sharing.

[0009] Furthermore, the network user-shared entangled photon pair source includes a laser, a single-mode fiber, a polarization controller, a wavelength division multiplexer, a dense wavelength division multiplexer, and an entangled photon pair source chip;

[0010] The single-mode fiber-coupled laser's power is partially allocated to a spectral analyzer for wavelength calibration. The polarization controller adjusts the polarization of the pump light before injecting the entangled photon pair source chip, so that the laser pumping the entangled photon pair source chip generates entangled photon pairs with varying frequencies and polarization degrees of freedom. The resulting quantum state is as follows:

[0011]

[0012] In the formula, N is the total number of frequency pairs generated, |H> / |V> represents the horizontal or vertical polarization state, and |ω s，n >|ω i，n > represents the frequency state of the signal or idler photon of the nth frequency pair, and satisfies the energy conservation condition; n = 1, 2, ..., N;

[0013] The wavelength division multiplexer filters out the pump light from the entangled photon pair source chip output as the feedback signal for the motor, and uses a ramping algorithm to optimize the coupling under unstable laboratory conditions; entangled photons and external noise are multiplexed into the same optical fiber link through a dense wavelength division multiplexer; the transmission of entangled photon pairs on noisy optical fiber links is considered as each frequency photon in a frequency-correlated photon pair having a separate transmission link and being measured separately.

[0014] Furthermore, the entangled photon pair source chip employs a non-ideal quarter-wavelength Bragg reflection waveguide, including silicon-on-insulator, silicon oxide, silicon nitride, lithium niobate, gallium arsenide, and aluminum gallium arsenide;

[0015] The structure is an Al with a thickness of 230 nm. 0.17 Ga 0.83 The core layer is alternately filled with 127nm thick Al. 0.28 Ga 0.72 As layer, 622nm thick Al 0.72 Ga0.28 A six-period Bragg structure composed of As layers is sandwiched in the middle, with a width of 5.1 μm, an etching depth of 4.15 μm, and a length of 4 mm.

[0016] Furthermore, the noise on the fiber optic link includes multiphoton pair generation, background photons, classical light, Raman scattering, and imperfect measurements.

[0017] Furthermore, the wavelength allocation module includes interconnected wavelength selection switches and wavelength division multiplexing devices, used to perform post-selection of the spectra of the photon pair source signal photon and idler photon, and modulate the bandwidth and wavelength interval of the spectrum according to different requirements.

[0018] Furthermore, the user can select the measurement basis vector in two ways: active selection using an optical switch and passive selection using a beam splitter.

[0019] Furthermore, the polarization analysis module includes a quarter-wave plate, a half-wave plate, an unequal-arm polarization-maintaining interferometer, a single-photon detector, and a time stamp module; the half-wave plate and the quarter-wave plate project photons onto two sets of basis vectors, Z-based or X-based; the eigenvectors of the Z-based basis are |H> / |V>, and the eigenvectors of the X-based basis are |A> / |D>.

[0020] In an unequal-arm polarization-maintaining interferometer, two orthogonal polarization states are connected to polarization-maintaining fibers of different lengths, converting them into |H> photons and |V> photons with different arrival times. The fundamental correlation delays of the Z-based and X-based polarization-maintaining interferometers, introduced by the two unbalanced fibers of different lengths, are converted into time delays, allowing a single-photon detector to obtain coincidence counts in four configurations within a single data accumulation. Each wavelength channel has an added delay, enabling each user to perform frequency-resolved detection using only one single-photon detector.

[0021] The time stamp module is used to collect and record single-photon detector signals.

[0022] Furthermore, the single-photon detector includes a photomultiplier tube, an avalanche photodetector, and a superconducting single-photon detector.

[0023] Furthermore, the time stamp module includes two types: a time stamp module based on a field-programmable gate array (FPGA) and a time stamp module based on an application-specific integrated circuit (ASIC).

[0024] Furthermore, the types of information that can be securely shared include quantum image encryption, quantum secret sharing, quantum meetings, and quantum digital signatures.

[0025] Beneficial effects:

[0026] First, the practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network of the present invention addresses the problem of entangled photon distribution in noisy fiber optic links by proposing the introduction of frequency-dependent quantum correlations into polarization-entangled photon pairs. Through frequency correlation, entangled photons can be extracted from noise, which can significantly enhance the tolerance of long-distance entangled photon distribution to noise in fiber optic links.

[0027] Secondly, the practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network of this invention utilizes frequency correlation to achieve noise resistance of entangled photons based on frequency-correlated polarization entangled photon pairs, thus realizing a noise-resistant multi-user entangled distribution quantum network. Compared with other entangled distribution quantum networks, its superior noise resistance makes this quantum network more adaptable to the complex environments in practical deployments, achieving a wider coverage range.

[0028] Third, the practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network of the present invention, by combining frequency reuse and time reuse technology, converts polarization states of different frequencies into different time-delay states, which can reduce the number of single-photon detectors for each user in the network to one, greatly reducing the resource consumption and cost of network deployment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a multi-user entangled distribution quantum network for practical noise-resistant quantum correlation assistance according to the present invention.

[0030] Figure 2 The figure shows the simulation results of the variation of entangled negative modes with noise ratio in the frequency quantum correlation-assisted multi-user entanglement distribution of the present invention.

[0031] Figure 3 This is a diagram showing the polarization entangled photon pair source and the noise immunity test setup for entangled photons in Embodiment 1 of the present invention.

[0032] Figure 4 This is a graph showing the variation of correlation spectrum intensity and lower bound of Bell state fidelity for entangled photons of six frequencies under Z-based and X-based classical optical noise for different intensities in Embodiment 1 of the present invention.

[0033] Figure 5 This is a graph showing the variation of average quantum bit error rate (QBER) and entanglement concurrency (I-concurrence) with the number of measurement frequency groups for different intensities of classical optical noise in Embodiment 1 of the present invention.

[0034] Figure 6 This is a diagram showing the experimental setup of a quantum-correlation-assisted three-user entanglement distribution noise-resistant quantum network in Embodiment 2 of the present invention.

[0035] Figure 7 This is a histogram showing the temporal correlation of detection events between any two users in the network in Embodiment 2 of the present invention.

[0036] Figure 8 These represent the bit error rate and key rate of different user links in the network in Embodiment 2 of the present invention.

[0037] Figure 9 This is a flowchart and result diagram of a user using a key to encrypt a quantum image in a network in Embodiment 2 of the present invention.

[0038] Figure 10 This is a flowchart and result diagram of users sharing quantum secrets using keys in a network in Embodiment 2 of the present invention. Detailed Implementation

[0039] The following embodiments are provided to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0040] like Figure 1 As shown, this invention discloses a practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network, which includes a source of entangled photon pairs shared by network users, a wavelength allocation module, an optical fiber link, and a polarization analysis module.

[0041] The network user-shared entangled photon pair source introduces frequency-dependent quantum correlation in polarization-entangled photon pairs, and extracts entangled photons from noise through frequency correlation;

[0042] The wavelength allocation module selects entangled photon pairs of different frequencies according to the frequency degrees of freedom and sends them to specific user pairs through a noisy fiber optic link. Each user randomly selects a measurement basis vector, uses a polarization analysis module for polarization encoding and decoding, extracts signal photons from noisy photons, and uses a single-photon detector to detect photons to establish a security key for secure information sharing.

[0043] Specifically, in a network, entangled photon pairs that generate entangled photon pairs with varying frequencies and polarization degrees of freedom produce quantum states of the following form: Where N is the total number of frequency pairs generated, |H> / |V> represents the horizontal or vertical polarization state, and |ω s > / |ω i > represents the frequency state of a signal or idler photon and satisfies the energy conservation condition. Based on the frequency degrees of freedom, wavelength-selective switches are used to select entangled photon pairs of different frequencies and transmit them to a specific user pair via a noisy fiber optic link, |ψ NTransmission over noisy fiber optic links can be viewed as frequency-correlated photon pairs where each frequency photon has its own transmission link and is measured individually. By selecting appropriate frequency channels and using polarization analysis modules for polarization encoding and decoding, users can extract signal photons from noisy photons. The probability of false coincidences between noise-noise photons or between noise-signal photons is reduced, while the probability of true coincidences between correlated photons remains essentially unchanged. Therefore, additional quantum correlations at frequencies can be used to extract signal photons from noisy photons, thus avoiding the influence of noise.

[0044] The quantum state transmission process described above was numerically simulated, with white noise introduced and amplitude damping coefficient Y∈[0.1, 0.3]. Entangled negative modes were used as the entanglement measure. Figure 2 Simulation results show the variation of entangled negative modes with noise ratio in frequency-quantum correlation-assisted multi-user entanglement distribution. When the number of frequencies N=1, the entangled negative modes decrease rapidly as the proportion of white noise increases. As the number of frequencies increases, the decreasing trend of entangled negative modes becomes more slow, indicating that frequency correlation assistance can improve the noise resistance in quantum state transmission.

[0045] Example 1

[0046] This embodiment is a test of polarization entangled photon pair source and entangled photon noise immunity, such as Figure 3As shown, in the entangled photon pair source section, 1% of the power of a single-mode fiber-coupled continuous wave (CW) laser with a center wavelength of 780.08 nm is allocated to a spectrometer for wavelength calibration, and a fiber polarization controller (PC) is used to adjust the polarization of the pump light before injection into the AlGaAs / GaAs semiconductor chip. The AlGaAs / GaAs semiconductor chip is a non-ideal quarter-wavelength Bragg reflection waveguide (BRW) sample. Its structure consists of a 230 nm thick Al0.17Ga0.83As core layer sandwiched between alternating 127 nm thick Al0.28Ga0.72As layers and 622 nm thick Al0.72Ga0.28As layers, with a width of 5.1 μm, an etching depth of 4.15 μm, and a length of 4 mm. Due to the low birefringence of the material, broadband polarization-entangled photon pairs can be directly generated via degenerate Type-II spontaneous parametric down-conversion (SPDC). In essence, a TE-polarized pump photon at frequency ωp is converted into a cross-polarized signal and an idler photon pair at frequencies ωs and ωi, where ωp = ωs + ωi. This design fully leverages the advantages of AlGaAs / GaAs semiconductor materials, which are well-suited for devices such as lasers and modulators and offer considerable second-order nonlinearity. A BRW structure is employed, achieving mode phase matching (PM) through bounded total internal reflection (TIR) ​​modes and quasi-bounded BRW modes. TIR modes are typically formed between high and low refractive index sandwiches, while BRW modes are propagated via transverse Bragg reflections between the core and periodic sandwiches. The pump light is coupled into the chip via a lens-tipped fiber mounted on a high-precision servo motor, and entangled photon pairs are coupled out from the other end. The total insertion loss of the chip is approximately 11 dB, including input-output coupling loss and propagation loss of the total internal reflection mode within the chip. To stabilize chip coupling, a 980 / 1550 wavelength division multiplexer (WDM) was used to filter out the pump light from the chip output as the feedback signal for the motor, and a ramp-up algorithm was employed to optimize coupling under unstable laboratory conditions. Due to energy conservation in the SPDC process, polarized entangled photons are anticorrelated in frequency. Then, the entangled photons and external noise are multiplexed into the same fiber link via a dense wavelength division multiplexer (DWDM).

[0047] In this embodiment, noise is introduced by transmitting a classical laser at 1591.26 nm along with a quantum signal into a 3 km long optical fiber. This is a realistic scenario for quantum communication systems operating on public DWDM networks. The simultaneous presence of classical and quantum signals in the same optical fiber can lead to several problems affecting quantum communication performance. The main sources of noise are crosstalk from classical light when the DWDM isolation is insufficient, and Raman scattering due to inelastic photon-phonon interactions. Since the wavelength of classical light is far from that of the quantum signal, appropriate filters can be used at the user end to remove crosstalk from non-adjacent channels. However, broadband Raman noise cannot be filtered out spectrally because it is in the same frequency band as the quantum signal. Raman cross-sections at different wavelengths were obtained using measurements of a 1555 nm center wavelength laser in a standard single-mode optical fiber as a reference. By using a wavelength selective switch (WSS), the spectra of signal photons (ranging from 1554.1 nm to 1557.1 nm) and idler photons (ranging from 1563.4 nm to 1566.4 nm) are post-selected to select 6 pairs, each with a full width at half maximum (FWHM) bandwidth of 0.4 nm and a wavelength spacing of 0.6 nm.

[0048] The polarization analysis module comprises a quarter-wave plate, a half-wave plate, an unequal-arm polarization-maintaining interferometer (UPMI), and a single-photon detector (SPD). The detector is an InGaAs avalanche-type SPD with a detection efficiency of 10%, a dark count rate of 800 Hz, and a dead time of 17 μs. In the interferometer, two orthogonal polarization states are connected to polarization-maintaining fibers of different lengths, thus converting them into differences in the arrival times of |H> and |V> (|A> and |D>). The fundamental correlation delays for Z and X are introduced by the difference in fiber length between the two unbalanced polarization-maintaining interferometers, converting the four polarization states into time-delayed states. Therefore, a single-photon detector can obtain coincidence counts in four configurations in a single data accumulation. Single-photon detection events are recorded by FPGA-based time-stamping units. Single-photon counts and coincidence counts are then extracted from these time-stamped records.

[0049] exist Figure 4 The paper presents the 6×6 joint spectral intensity in the Z={H, V} and X={A, D} bases at four classical laser powers, with an input pump power of 30 mW, a coincidence window of 0.5 ns, and an integration time of 120 s. The results are consistent with expectations; increasing the classical laser power leads to an increase in noise photons that randomly spread across the entire spectrum, while the correlation signal distributed in the diagonal elements remains unchanged. A lower bound for the fidelity of the Bell states can be estimated by projecting measurements onto two mutually unbiased bases. This decrease in fidelity can be seen as an intuitive explanation for the increased mixing of quantum states in noisier channels.

[0050] Figure 5 The average qubit error rate (QBER) of the Z and X bases is shown under different classical optical powers and with varying numbers of measurement frequencies. QBER is determined by using primitive coincidence counts on each base: QBERz = (CHH + CVV) / (CHH + CHV + CVH + CVV), QBERx = (CDA + CAD) / (CDA + CDD + CAD + CAA). To investigate the effect of different measurement frequencies, i.e., the coarseness of frequency partitioning (FD), QBER was estimated using 1×1, 2×2, 3×3, and 6×6 matrices. The results show that QBER decreases significantly with increasing measurement frequency number. This indicates that in quantum networks, especially in high-noise quantum channels, using a larger number of frequencies N provides greater noise resilience. Figure 5 It also gives the results for four classical noise power conditions based on C≥V. D / A +V H / V -1 represents the result of calculating the lower bound of the entanglement measure I-concurrence. All experimental results indicate that selecting more frequencies for measurement improves the resistance to noise in entangled photon transmission.

[0051] Example 2

[0052] This embodiment, as a complete demonstration of the full utilization of broadband entanglement and noise resilience in quantum communication networks, realizes a fully connected three-user entangled distribution quantum network. Figure 6 In this method, network users share a source of entangled photon pairs, generating broadband polarization-entangled photon pairs. Three channels {CH32, CH13}, {CH11, CH09}, and {CH34, CH30} are selected through multiplexing and demultiplexing and assigned to different users. Users perform measurements using the same polarization analysis module as in Example 1. Noise in the fiber channels is again introduced using classical lasers, with the laser power in each fiber set to -23 dBm to achieve a receiving sensitivity of 10 Gbps classical signals. In the network, users Alice, Bob, and Charlie are connected using 4.075 km (loss 1.9 dB), 4.072 km (loss 1.8 dB), and 3.054 km (loss 1.2 dB) of fiber, respectively. During the receiving phase, photons incident on the polarization analysis module are passively selected by a 50:50 beam splitter (BS) to measure the basis vectors. Figure 6The polarization analysis module uses an HV basis vector as the upper output and an AD basis vector as the lower output. For each measurement basis, UPMI is used to identify polarization via the relative arrival time of photons. An additional delay is added between the two basis vectors to further differentiate the basis vector information. The two outputs are connected via a 50:50 coupler (BS) to reduce the number of single-photon detectors required, at the cost of an additional 3dB of loss. Due to the lack of an additional SPD, only two users operate the system at a time, and a relative delay is added to distinguish between different user combinations.

[0053] Figure 7 The histograms corresponding to the time correlations in the three sets of user communications are displayed, with sixteen coincident events marked, representing real-time projected measurements on the basis of Z and X. Figure 8 The figure shows the variation in average QBER and filtered key rate per minute using a 100 GHz DWDM splitting frequency during laboratory testing over 65 hours, with average QBERs of 5.63%, 6.58%, and 7.21%, respectively. The steep spikes in the figure are primarily caused by room temperature variations, which lead to perturbations in coupling efficiency and polarization states transmitted in the fiber. For comparison, half-hour data were also recorded using a 200 GHz DWDM splitting frequency, with average QBERs of 11.07%, 13.51%, and 12.67% (indicated by black dashed lines), which are above the 11% QBER threshold and significantly higher than the QBER at 100 GHz DWDM. Clearly, quantum correlation-assisted multi-user entanglement distribution is practically deployable in real-world fiber optic communication networks.

[0054] During key negotiation, this embodiment employs low-density parity-check (LDPC) codes combined with the belief propagation (BP) algorithm for error correction, which offers near-capacity performance and low complexity. The BP algorithm provides optimal decoding when the LDPC code is free of cycles, making cycle reduction crucial. Algorithms based on the edge-by-edge growth (PEG) pattern are used to construct LDPC codes with large perimeters. To maximize the security of a finite key length, for the standard QKD security definition, a protocol can be defined as ε if ε1 is correct and ε2 is secret. QKD It is safe, where 0 < ε1 + ε2 ≤ ε QKD Satisfying 2 -t +2ε pe (v,ξ)+ε pa (v)≤ε QKD Assume the implemented finite key length is... Where m is the screening key length, 0 < α < 1. The parameter estimation (pe) and privacy amplification (pa) error functions can be defined as follows: The correctness error is 2.-t =10 -(s+2) The safety parameter is ε QKD =10 -s Therefore, by following the above inequality under a fixed block length and security level s=9, the finite key length l is maximized through optimization of {α, β, v, ξ}. By optimizing {α, β, v, ξ}, parameter values ​​{0.262, 0.080, 0.015, 0.013} were found for Alice and Bob, {0.149, 0.100, 0.014, 0.012} for Bob and Charlie, and {0.191, 0.09, 0.015, 0.013} for Alice and Charlie, allowing for maximum keys of 388.56kb, 199.72kb, and 254.63kb respectively. These keys can be used for quantum image encryption and quantum secret sharing.

[0055] Many studies utilize quantum keys to encrypt raw images via direct XOR operations. However, while quantum keys provide unconditional security, this encryption strategy is vulnerable to image-specific attacks due to strong redundancy and correlation among adjacent pixels. For example, an attacker could use a cropping attack to compromise the integrity of the encrypted image, preventing legitimate users from obtaining the correct information. Unlike the direct XOR operation commonly used in quantum image encryption, a Shannon confusion-diffusion architecture is employed to protect encrypted images from image-specific attacks, such as cropping attacks. In this architecture, confusion involves shuffling pixel positions without changing their values, while diffusion involves sequentially modifying pixel values ​​using a secret key. Figure 9 As shown, each sender performs three rounds of obfuscation, followed by two rounds of diffusion and obfuscation to encrypt the original image. The sender then transmits the encrypted image to the receiver via a classic channel, where the receiver performs the inverse encryption transformation to obtain the decrypted image.

[0056] Unlike many quantum secret-sharing protocols that rely on the sequential transmission of quantum states between players, each player encodes their data into a state using quantum transformations. The proposed strategy can generate a set of unconditionally secure keys between any two users. This facilitates the direct establishment of a quantum secret-sharing network, enabling dealers to share secret messages with any chosen player, thereby enhancing the practical feasibility and commercial potential of quantum secret sharing. Figure 10 As shown, dealer Alice executes The secret message M is encrypted, and then the resulting encrypted message C is transmitted to two players, Bob and Charlie, via a classic channel. Players can share their keys and use equations... The received message is decrypted, thereby independently reconstructing the secret message.

[0057] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A practical, noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network, characterized in that, The multi-user entangled distribution quantum network includes a source of entangled photon pairs shared by network users, a wavelength allocation module, an optical fiber link, and a polarization analysis module; The network user-shared entangled photon pair source introduces frequency-dependent quantum correlation in polarization-entangled photon pairs, and extracts entangled photons from noise through frequency correlation; The network user-shared entangled photon pair source includes a laser, a single-mode fiber, a polarization controller, a wavelength division multiplexer, a dense wavelength division multiplexer, and an entangled photon pair source chip; The single-mode fiber-coupled laser allocates a portion of its power to a spectral analyzer for wavelength calibration. The polarization controller adjusts the polarization of the pump light before injecting the entangled photon pair source chip, ensuring that the laser pumps the entangled photon pair source chip to generate entangled photon pairs with varying frequencies and polarization degrees of freedom. The resulting quantum state is as follows: ； In the formula, N is the total number of frequency pairs generated. Indicates horizontal or vertical polarization state. Indicates the first The frequency states of a pair of signal or idler photons, and satisfy the energy conservation condition; ; The wavelength division multiplexer filters out the pump light from the source chip output of the entangled photon pair as the feedback signal of the motor, and uses a ramping algorithm to optimize the coupling under unstable laboratory conditions; the entangled photons and external noise are multiplexed into the same optical fiber link through a dense wavelength division multiplexer. The transmission of entangled photon pairs over noisy fiber optic links is considered as each frequency photon in a frequency-correlated photon pair having its own transmission link and being measured separately. The wavelength allocation module selects entangled photon pairs of different frequencies according to the frequency degrees of freedom and sends them to specific user pairs through a noisy fiber optic link. Each user randomly selects a measurement basis vector, uses a polarization analysis module for polarization encoding and decoding, extracts signal photons from noisy photons, and uses a single-photon detector to detect photons to establish a security key for secure information sharing.

2. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, The entangled photon pair source chip uses a non-ideal quarter-wavelength Bragg reflection waveguide, including silicon-on-insulator, silicon oxide, silicon nitride, lithium niobate, gallium arsenide, and aluminum gallium arsenide; The structure is an Al with a thickness of 230 nm. 0.17 Ga 0.83 The core layer is alternately filled with 127 nm thick Al. 0.28 Ga 0.72 As layer, 622 nm thick Al 0.72 Ga 0.28 A six-period Bragg structure composed of As layers is sandwiched in the middle, with a width of 5.1 μm, an etching depth of 4.15 μm, and a length of 4 mm.

3. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, Noise on the fiber optic link includes multiphoton pair generation, background photons, classical light, Raman scattering, and imperfect measurements.

4. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, The wavelength allocation module includes interconnected wavelength selection switches and wavelength division multiplexing devices, used to perform post-selection of the spectra of the photon pair source signal photon and idler photon, and modulate the bandwidth and wavelength interval of the spectrum according to different requirements.

5. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, The user selects the measurement basis vector in two ways: active selection using an optical switch and passive selection using a beam splitter.

6. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, The polarization analysis module includes a quarter-wave plate, a half-wave plate, an unequal-arm polarization-maintaining interferometer, a single-photon detector, and a time-stamping module; the half-wave plate and quarter-wave plate project photons onto two sets of basis vectors, either Z-based or X-based; the eigenvectors of the Z-based basis are... The eigenvalues ​​of the X-base are ; In an unequal-arm polarization-maintaining interferometer, two orthogonal polarization states are connected to polarization-maintaining fibers of different lengths, and are converted into polarization states with different arrival times. photon sum Photons, and introduce fundamental correlation delays of Z-based and X-based through two unbalanced polarization-maintaining interferometers of different fiber lengths, convert the four polarization states into time delays, enabling single-photon detectors to obtain coincidence counts in four configurations in a data accumulation; wherein, a delay is added to each wavelength channel, so that each user uses only one single-photon detector for frequency-resolved detection. The time stamp module is used to collect and record single-photon detector signals.

7. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 6, characterized in that, The single-photon detectors include photomultiplier tubes, avalanche photodetectors, and superconducting single-photon detectors.

8. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 6, characterized in that, The time stamp module includes two types: a time stamp module based on a field-programmable gate array (FPGA) and a time stamp module based on an application-specific integrated circuit (ASIC).

9. The practical noise-resistant quantum correlation-assisted multi-user entangled distribution quantum network according to claim 1, characterized in that, Securely shared information types include quantum image encryption, quantum secret sharing, quantum meetings, and quantum digital signatures.

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