A chip-fiber-chip quantum teleportation network node based on topology protection and a control method thereof

Abstract

The application discloses a chip-fiber-chip quantum teleportation network node based on topology protection and a control method thereof. The network node comprises a topology photon chip (a sending end, comprising a quantum state generation unit and an encoding unit), a topology structure fiber, a topology photon chip (a receiving end, comprising a decoding unit and a quantum state verification unit), a chip-fiber coupling interface, a projection geometry regulation module and a synchronous control module. The projection geometry regulation module regulates the projection angle θ (θ=arctan(β_s / β_r), β_r²+β_s²=1) of each topology photon crystal unit through an external field, realizes the encoding, topology protection transmission and reading of the quantum state, and guarantees the transmission reliability in real time through the whole-link topology stability criterion. The application realizes the topology protection quantum teleportation of the chip-fiber-chip whole link, the transmission distance is greater than or equal to 10 km, the whole-link fidelity is greater than or equal to 0.95, and is suitable for quantum communication network and quantum internet scenes.

Description

Technical Field

[0001] This invention relates to the fields of quantum communication network technology and integrated photonics technology, specifically to a chip-fiber-chip quantum teleportation network node based on topology protection and its control method. This invention can be applied to quantum communication networks, quantum repeater nodes, quantum internet, distributed quantum computing, intercity quantum communication, and other fields, and is particularly suitable for quantum network node applications that require quantum state generation at the chip level, topology-protected transmission via optical fiber, and quantum state reception and verification at the chip level. Background Technology

[0002] Quantum teleportation is a core protocol for quantum communication and quantum networks. By sharing quantum entanglement and using classical communication, it transmits quantum states from one node to another without the need to transport the physical carrier itself. In recent years, quantum teleportation has moved from laboratory demonstrations to system-level integration. In 2025, a team from Tsinghua University achieved inter-chip quantum teleportation over an optical fiber distance of 12.3 kilometers, increasing the transmission distance by three orders of magnitude. A team from the University of Science and Technology of China achieved inter-chip quantum controlled NOT gate teleportation with a gated state fidelity of 95.69% over a 5-meter optical fiber interconnection distance. Chip-fiber-chip quantum teleportation in star-topology quantum networks has been experimentally verified. The existing technology mainly has the following problems: (I) Quantum state decoherence in optical fiber transmission When quantum states are transmitted over long distances in optical fibers, they are affected by dispersion, nonlinear effects, and environmental disturbances, resulting in significant decoherence. Existing solutions rely on active feedback systems to suppress the effects of fiber length fluctuations, but lack passive immune mechanisms based on topology protection. (ii) Insufficient chip-fiber coupling efficiency The coupling between the quantum chip and the optical fiber suffers from mode mismatch and coupling loss, affecting the overall fidelity of quantum teleportation. Existing solutions lack chip-fiber coupling interface designs based on topology. (iii) Lack of end-to-end topology protection architecture In existing chip-fiber-chip quantum teleportation schemes, a unified topology protection mechanism is lacking for the generation, transmission, and reception of quantum states. Topology protection has been theoretically proven to effectively suppress decoherence, but it has not yet been implemented in a complete chip-fiber-chip link. (iv) Network nodes lack complete topology protection functionality integration Existing quantum network nodes typically only have a single quantum state generation or reception function, lacking a complete solution that integrates topological photonic chips, topological fiber transmission, and topological quantum state verification into the same node. To address the above problems, this invention provides a chip-fiber-chip quantum teleportation network node based on topology protection and its control method. Summary of the Invention

[0003] (a) Purpose of the invention This invention aims to solve the technical problems in existing chip-fiber-chip quantum teleportation, such as severe decoherence in fiber transmission, insufficient chip-fiber coupling efficiency, lack of full-link topology protection architecture, and incomplete integration of network node functions. It provides a chip-fiber-chip quantum teleportation network node based on topology protection and its control method, which integrates the complete functions of topological quantum state generation, topological fiber transmission, and topological quantum state reception and verification in a single node. (II) Technical Solution This invention provides a chip-fiber-chip quantum teleportation network node based on topology protection, characterized in that it comprises: A topological photonic chip (transmitter) is disposed on a semiconductor substrate and includes a topological photonic crystal quantum state generation unit and a topological photonic crystal encoding unit, used to generate and encode the quantum state to be transmitted; A fiber with a topological structure is connected to the output end of the topological photonic chip (transmitter) for transmitting quantum state optical signals under topological protection; A topological photonic chip (receiver) is disposed on a semiconductor substrate and includes a topological photonic crystal decoding unit and a topological photonic crystal quantum state verification unit, used to receive and verify the transmitted quantum state; A chip-fiber coupling interface is provided at the output end of the topological photonic chip (transmitter) and the input end of the topological photonic chip (receiver) to achieve efficient optical coupling between the topological photonic chip and the optical fiber with topological structure. A projection geometry control module is connected to the topological photonic chip (transmitter) and the topological photonic chip (receiver) to control the projection angle of each topological photonic crystal unit through an external field, thereby realizing the encoding, transmission and reading control of quantum states; A synchronization control module is connected to the topological photonic chip (transmitter), the topological optical fiber, and the topological photonic chip (receiver) to coordinate the timing of quantum state transmission, transmission, and reception. Topological photonic chip (transmitter): The topological photonic chip (transmitter) includes: A topological photonic crystal quantum state generation unit is composed of two or more materials with different dielectric constants arranged periodically, and has a non-zero topological Chern number. It is used to generate entangled photon pairs or single photon sources. A topological photonic crystal encoding unit is connected to the quantum state generation unit and is used to encode the quantum information to be transmitted into the quantum state of the optical signal; A topological photonic crystal waveguide, connecting the quantum state generation unit and the encoding unit, is used to transmit optical signals under topological protection; A gate electrode array is disposed on each topological photonic crystal unit and is used to apply a control voltage to adjust the projection angle. Fiber optic topology: The topological structured optical fiber is at least one of topological insulator core fiber (SG00113) or topological photonic crystal cladding fiber (SG00114), and has a non-zero topological Chern number, used to provide topological protection for quantum state optical signals during optical fiber transmission. The optical fiber with the described topology supports a transmission distance of ≥10km, and the topology protection reduces transmission loss by more than 50% compared to ordinary optical fiber. Topological photonic chip (receiver): The topological photonic chip (receiver) includes: A topological photonic crystal decoding unit is connected to the chip-fiber coupling interface for decoding quantum states from received optical signals; A topological photonic crystal quantum state verification unit is connected to the decoding unit and is used to verify the fidelity of quantum teleportation through Bell state measurement; A topological photonic crystal waveguide connects the decoding unit and the verification unit, and is used to transmit optical signals under topological protection; A gate electrode array is disposed on each topological photonic crystal unit and is used to apply a control voltage to adjust the projection angle. Chip-fiber coupling interface: The chip-fiber coupling interface includes: A grating coupler or end-face coupler is disposed at the edge of the topological photonic chip to couple optical signals within the chip to an optical fiber; A mode conversion structure is used to match the mode distribution of topological photonic crystal waveguides and topological fiber optics; A coupling efficiency monitoring unit is used to monitor the coupling efficiency in real time and feed it back to the projection geometry control module. Mathematical framework for projection geometry control: Definition of projection angle: The projection angle θ is defined as: θ = arctan(β_s / β_r), β_r² + β_s² = 1 Definition of topological Chern number: The topological Chern number C of the topological photonic crystal unit is defined as: C = (1 / 2π) ∮ F · dS Where F is the Berry curvature and S is the closed surface of the Brillouin zone. Relationship between quantum state encoding and projection angle: The topological photonic crystal encoding unit encodes quantum states into topologically protected optical signals by adjusting the projection angle θ. The encoding fidelity F_encode satisfies the following relationship with the projection angle θ: F_encode(θ) = F_max · exp[-(θ - θ_enc)² / 2σ_enc²] Where F_max is the maximum coding fidelity, θ_enc is the optimal coding projection angle, and σ_enc is the coding bandwidth. End-to-end topology stability criterion: During operation, the projection geometry control module continuously monitors the rate of change of the projection angle of each topological photonic crystal unit in the network node. The following criteria are used to determine whether the entire link is in a stable topological state: Σ γ_i · _i² ≥ Σ |1 − k_i| · |∂C_i / ∂θ_i| · | _i| · h / 2 Where γ_i is the topology loss rate of the i-th cell. _i is the rate of change of the projection angle of the i-th element, C_i is the topological Chern number of the i-th element, k_i is the restitution coefficient, and h is Planck's constant. When the criterion is met, the entire link is in a stable topological state, and the fidelity of quantum teleportation is guaranteed; when the criterion is not met, feedback adjustment is triggered. Full-link quantum teleportation fidelity: The end-total quantum teleportation fidelity of the network nodes, F_total, is determined by the following formula: F_total = F_encode · F_fiber · F_decode · F_BSM Where F_encode is the encoding fidelity, F_fiber is the fiber optic transmission fidelity (protected by topology protection), F_decode is the decoding fidelity, and F_BSM is the Bell state measurement fidelity. When the end-total topology stability criterion is met, F_total ≥ 0.95. (III) Beneficial Effects Full-link topology protection: From quantum state generation and fiber transmission to quantum state reception and verification, the entire process is protected by the topology Chern number, effectively suppressing decoherence and transmission loss; High-efficiency chip-fiber coupling: The topological structure of the grating coupler and mode conversion structure enables high-efficiency optical coupling between the chip and the fiber, with a coupling efficiency of ≥90%. Chip-side integration: Both the transmitter and receiver are integrated into the topological photonic chip, which is small in size, highly stable, and suitable for large-scale deployment; End-to-end stability criteria: For the first time, a quantitative criterion for the topological stability of the entire chip-fiber-chip link has been established to ensure transmission reliability in real time; Synergy with SG series: Forms a complete fiber-chip-optical path synergy system with SG00111, SG00115, and SG00118; Long-distance transmission capability: Topology-protected optical fiber supports quantum state transmission of ≥10km, meeting the needs of intercity quantum communication. Attached Figure Description

[0004] Figure 1 This is a schematic diagram of the overall structure of a chip-fiber-chip quantum teleportation network node based on topology protection, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the internal structure of a topological photonic chip (transmitter) provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the chip-fiber coupling interface provided in an embodiment of the present invention. Figure 4 The flowchart of the end-to-end topological stability criterion and quantum teleportation control provided for embodiments of the present invention. Detailed Implementation

[0005] Example 1: Chip-Fiber-Chip Quantum Teleportation Network Node Based on Topology Protection Step 1: Fabrication of a topological photonic chip (transmitter) A topological photonic chip (transmitter) is fabricated on an SOI substrate. The chip comprises a topological photonic crystal quantum state generation unit (honeycomb lattice structure, lattice constant a = 440 nm) and a topological photonic crystal encoding unit, both with a non-zero topological Chern number C = 1. The operating wavelength is 1550 nm. The projection angle θ is defined as θ = arctan(β_s / β_r), satisfying β_r² + β_s² = 1. Step 2: Fabrication of a topological photonic chip (receiver) A topological photonic chip (receiver) is fabricated on an SOI substrate, comprising a topological photonic crystal decoding unit and a topological photonic crystal quantum state verification unit, with a non-zero topological Chern number C=1. Step 3: Fabrication of topological fiber It adopts topological insulator core fiber (SG00113) or topological photonic crystal cladding fiber (SG00114), with a length ≥10km and a non-zero topological Chern number. Step 4: Configure the chip-fiber coupling interface A grating coupler is fabricated at the edge of the transmitting and receiving chips to achieve efficient coupling between the chip waveguide and the optical fiber. The coupling efficiency is ≥90%. Step 5: Configure the projection geometry control module and synchronization control module The projection geometry control module is connected to the gate electrode arrays of the transmitting and receiving chips, independently controlling the projection angle of each unit. The synchronization control module coordinates the timing of quantum state transmission, transmission, and reception. Step 6: Verification of Quantum Teleportation The transmitting chip generates and encodes quantum states, which are transmitted to the receiving chip via a fiber optic topology. The receiving chip then performs decoding and Bell state measurement. The measured end-to-end fidelity F_total ≥ 0.95, and the transmission distance ≥ 10 km. Example 2: Deployment of Star Topology Quantum Network Nodes Step 1: Deploy multiple network nodes Multiple Q00142 network nodes are deployed in a star-topology quantum network, including user nodes, relay nodes, and a central node. Step 2: Quantum teleportation between nodes User nodes are connected to relay nodes via fiber optic topology, and relay nodes are connected to the central node via fiber optic topology, enabling multi-hop quantum teleportation. Step 3: Proactive Feedback and Stability Optimization The synchronization control module of each node adopts an active feedback system to suppress the influence of fiber length fluctuations and ensure the stability of quantum interference. Step 4: Network-level fidelity verification After multi-hop transmission, the overall network fidelity is ≥0.90. Terminology Explanation

[0006] Terminology Meaning Chip-Fiber-Chip Quantum Teleportation: A complete teleportation link in which the quantum state is generated at the transmitting chip, transmitted through the optical fiber, and received at the receiving chip. Topological photonic chips are optical quantum chips based on topological photonic crystal structures, supporting topologically protected quantum state generation, encoding, decoding, and verification. Topologically protected optical fibers (topologically insulator-core fibers or topologically photonic crystal clad fibers) are fibers with non-zero topological Chern numbers that support topology-protected optical signal transmission. Chip-fiber coupling interface realizes an interface structure for efficient optical coupling between topological photonic chips and optical fibers. The projection angle (θ) is a geometric parameter describing the projection direction in fiber bundle projection mapping, where θ = arctan(β_s / β_r). End-to-end topology stability criteria: Quantitative criteria for determining whether the entire chip-fiber-chip link is in a stable topological state. A star-topology quantum network is a quantum network topology structure consisting of a central node as the core and multiple user nodes connected by optical fibers.

Claims

1. A chip-fiber-chip quantum teleportation network node based on topology protection, characterized in that, include: A topological photonic chip (transmitter) is disposed on a semiconductor substrate and includes a topological photonic crystal quantum state generation unit and a topological photonic crystal encoding unit, used to generate and encode the quantum state to be transmitted; A fiber with a topological structure is connected to the output end of the topological photonic chip (transmitter) for transmitting quantum state optical signals under topological protection; A topological photonic chip (receiver) is disposed on a semiconductor substrate and includes a topological photonic crystal decoding unit and a topological photonic crystal quantum state verification unit, used to receive and verify the transmitted quantum state; A chip-fiber coupling interface is provided at the output end of the topological photonic chip (transmitter) and the input end of the topological photonic chip (receiver) to realize optical coupling between the topological photonic chip and the optical fiber of the topological structure. A projection geometry control module is connected to the topological photonic chip (transmitter) and the topological photonic chip (receiver) to control the projection angle of each topological photonic crystal unit through an external field, thereby realizing the encoding, transmission and reading control of quantum states; A synchronization control module is connected to the topological photonic chip (transmitter), the topological optical fiber, and the topological photonic chip (receiver) to coordinate the timing of quantum state transmission, transmission, and reception.

2. The network node according to claim 1, characterized in that: The topological photonic crystal unit is composed of two or more materials with different dielectric constants arranged periodically, and has a non-zero topological Chern number; the topological structure fiber is at least one of topological insulator core fiber or topological photonic crystal cladding fiber.

3. The network node according to claim 1, characterized in that: The projection angle θ is defined as θ = arctan(β_s / β_r), where β_r and β_s satisfy the projection constraint β_r² + β_s² = 1; the topological Chern number C is controlled by the projection angle θ, C(θ) = C_max · sin(θ - θ0).

4. The network node according to claim 1, characterized in that: The topological photonic crystal encoding unit encodes the quantum state into a topologically protected optical signal by adjusting the projection angle θ, with an encoding fidelity of F_encode(θ) = F_max · exp[-(θ - θ_enc)² / 2σ_enc²].

5. The network node according to claim 1, characterized in that: The chip-fiber coupling interface includes a grating coupler or end-face coupler, a mode conversion structure, and a coupling efficiency monitoring unit, with a coupling efficiency ≥90%.

6. The network node according to claim 1, characterized in that: During operation, the projection geometry control module continuously monitors the rate of change of the projection angle of each topological photonic crystal unit in the network node. _i, according to the end-to-end topology stability criterion Σ γ_i· _i² ≥ Σ |1−k_i|·|∂C_i / ∂θ_i|·| _i|·h / 2 determines whether the entire link is in a stable topology state. If the criterion is not met, feedback adjustment is triggered.

7. The network node according to claim 1, characterized in that: The end-total quantum teleportation fidelity of the network node is F_total = F_encode · F_fiber · F_decode · F_BSM, and F_total ≥ 0.95 when the end-total topology stability criterion is satisfied.

8. The network node according to claim 1, characterized in that: The optical fiber with the described topology supports a transmission distance of ≥10km, and the topology protection reduces transmission loss by more than 50% compared to ordinary optical fiber.

9. A control method for a chip-fiber-chip quantum teleportation network node based on topology protection, characterized in that, Includes the following steps: (1) Configure the projection angle of the topological photonic chip (transmitter) through the projection geometry control module to encode the quantum state into a topologically protected optical signal; (2) The encoded optical signal enters the optical fiber of the topology structure through the chip-fiber coupling interface and is transmitted under topology protection; (3) After the optical signal is transmitted through the optical fiber of the topology structure, it enters the topology photonic chip (receiver) through the chip-fiber coupling interface. (4) Configure the projection angle of the topological photonic chip (receiver) through the projection geometry control module to decode the received optical signal; (5) Verify the fidelity of quantum teleportation by performing Bell state measurements using a topological photonic crystal quantum state verification unit; (6) The synchronization control module coordinates the timing of quantum state transmission and reception to ensure synchronization of each link.

10. The method according to claim 9, characterized in that: The transmission distance of the optical fiber with the topology structure described in step (2) is ≥10km; the fidelity of the full-link quantum teleportation described in step (5) is ≥0.95.

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