An on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array and a preparation method thereof

Abstract

The application discloses a kind of based on topological photonic crystal waveguide array integrated quantum state transmission device and preparation method thereof on chip.It includes SOI substrate, topological photonic crystal waveguide array (containing sending end waveguide and receiving end waveguide, with same nonzero topological Chen number C_A=C_B ≠0), projection geometry control module, quantum state encoding / decoding unit, fiber-chip coupling interface and topological photon dynamic routing unit.Projection geometry control module controls the projection angle θ (θ=arctan (β_s / β_r), β_r²+β_s²=1) of waveguide to critical value θ_A=θ_B=π / 2 by electro-optic or thermo-optic effect, realize macroscopic quantum state on-chip topological protection transmission.Fiber-chip coupling interface cooperates with SG00111 and SG00115, and topological photon dynamic routing unit cooperates with SG00118.The application realizes macroscopic quantum state transmission function on standard SOI platform, with the outstanding advantages of topological protection, controllable, room temperature operation, suitable for quantum chip interconnection and on-chip quantum communication and the like scenes.

Description

Technical Field

[0001] This invention relates to the fields of quantum information transmission technology and integrated photonics technology, specifically to an on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array and its fabrication method. This invention can be applied to fields such as macroscopic quantum state on-chip transmission, quantum chip interconnection, quantum information processing, on-chip quantum communication, and quantum-enhanced sensing, and is particularly suitable for applications that realize topologically protected transmission of macroscopic quantum states on a standard silicon-based photonic chip platform. Background Technology

[0002] The theoretical foundation of macroscopic quantum state transmission (the interstellar gateway) is Geometric Unified Field Theory (GUFT): a physical system is a projection section of the total space of a fiber bundle onto the bottom space. The essence of macroscopic quantum state transmission is the remapping of this section within the fiber bundle, independent of path propagation in the bottom space. The core condition for realizing macroscopic quantum state transmission is that the topologies of the transmitting and receiving ends have the same non-zero topological Chern number (C_A = C_B), and the projection angles at both ends synchronously reach critical values ​​(θ_A = θ_B = π / 2, β_r = 0). With the development of silicon-based photonic integration technology, integrating macroscopic quantum state transmission capabilities onto standard photonic chips has become an important direction in the field of quantum information. Topological photonic crystals (TPCs), due to their supported topologically protected boundary states, can effectively suppress backscattering losses caused by fabrication defects and bends, providing a new path for high-performance, large-scale photonic integrated systems. In recent years, waveguides based on valley photonic crystals (VPCs) have been designed and experimentally verified on the silicon-on-insulator (SOI) platform, reducing splicing loss from 0.59 dB to 0.009 dB under 100 nm lateral splicing misalignment, a reduction of 98.3%. The existing technology mainly has the following problems: (i) Lack of on-chip integration solutions for quantum state transmission Existing macroscopic quantum state transport schemes are mainly based on discrete topological material elements (such as MnBi2Te4 heterojunctions), and have not yet been integrated with standard silicon-based photonic chip platforms. Discrete schemes are large in size, high in cost, and difficult to scale up. (ii) Lack of projection angle modulation mechanism in topological photonic crystals The topological state of existing topological photonic crystal waveguides is fixed after manufacturing, lacking the ability to dynamically control the projection angle based on external fields (electric field, optical field), and thus failing to meet the requirement of precise control of the critical projection angle value θ=π / 2 for macroscopic quantum state transmission. (iii) Lack of on-chip interface with SG series fiber optic storage networks Existing SG series patents (SG00111 Fiber Optic Optical Storage System, SG00115 Distributed Fiber Optic Storage Network System) have achieved topology-protected optical storage and transmission on fiber optic platforms, but lack an interface scheme for efficiently coupling quantum states from the fiber optic network to on-chip processing units. (iv) Lack of on-chip quantum state routing and switching capabilities Existing topological photonic crystal devices are limited in function and lack on-chip quantum state routing and switching capabilities in conjunction with SG00118 (topological photonic dynamic optical routing chip). To address the above problems, this invention provides an on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array and its fabrication method. Summary of the Invention

[0003] (a) Purpose of the invention This invention aims to address the technical problems in existing macroscopic quantum state transmission schemes, such as the lack of on-chip integration, the absence of a topological photonic crystal projection angle control mechanism, the lack of an on-chip interface with SG series optical fiber storage networks, and the lack of on-chip quantum state routing capabilities. It provides an on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array and its fabrication method, realizing on-chip topological protected transmission, storage, and routing of macroscopic quantum states on a standard SOI platform. (II) Technical Solution This invention provides an on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array, characterized in that it comprises: A semiconductor substrate (SOI substrate); A topological photonic crystal waveguide array is disposed on the semiconductor substrate, comprising a first topological photonic crystal waveguide (transmitter) and a second topological photonic crystal waveguide (receiver), which have non-zero topological Chern numbers C_A and C_B respectively (C_A = C_B ≠ 0). A projection geometry control module is connected to the topological photonic crystal waveguide array and is used to control the projection angle θ of each waveguide through an external field (electric field or optical field); A quantum state encoding unit is connected to the input end of the first topological photonic crystal waveguide and is used to encode the macroscopic quantum state to be transmitted into a topologically protected optical signal. A quantum state decoding unit is connected to the output of the second topological photonic crystal waveguide to decode the received optical signal into a macroscopic quantum state; A fiber-to-chip coupling interface is connected to the first topological photonic crystal waveguide and the second topological photonic crystal waveguide for optical signal coupling with the SG series optical fiber storage network; A topological photonic dynamic routing unit is connected to the topological photonic crystal waveguide array and is used to route optical signals to the target output port according to the routing table. Core Materials Platform: The topological photonic crystal waveguide array is fabricated based on the SOI platform: Substrate: Silicon substrate, thickness 500-700μm; Buried oxide layer: silicon dioxide, thickness 2-3μm; Top-layer silicon: 220 nm thick, used to fabricate topological photonic crystal structures. The aforementioned topological photonic crystal waveguide is a valley photonic crystal (VPC) waveguide, formed by splicing together two photonic crystal regions with different topological properties to create topological boundary states. It has a honeycomb lattice structure with a lattice constant a = 420-460 nm and an operating wavelength of 1550 nm. 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 aforementioned topological photonic crystal waveguide is defined as follows: C = (1 / 2π) ∮ F · dS Where F is the Berry curvature and S is the closed surface of the Brillouin zone. The relationship between projection angle and Chen number: The topological Chern number C is controlled by the projection angle θ: C(θ) = C_max · sin(θ - θ0) Where C_max is the maximum topological Chern number and θ0 is the theoretically optimal projection angle. Projection angle adjustment mechanism: The projection geometry control module controls the projection angle θ of the topological photonic crystal waveguide in the following manner: (1) Electro-optic manipulation: Integrating a PIN or PN junction on a topological photonic crystal waveguide, and changing the effective refractive index of the waveguide by applying a reverse bias voltage, thereby changing the projection angle: θ(V) = θ0 + α · V + β · V² Where V is the applied voltage, and α and β are the electro-optic coefficients. (2) Thermo-optical manipulation: A micro heating electrode is integrated above the topological photonic crystal waveguide, and the refractive index of the waveguide is changed through the thermo-optical effect, thereby changing the projection angle: θ(T) = θ0 + γ · (T - T0) Where T is temperature and γ is the thermo-optic coefficient. Critical synchronization condition: The projection geometry control module synchronously modulates the projection angles of the transmitting and receiving ends to: θ_A = θ_B = π / 2, β_r^(A) = β_r^(B) = 0 At this point, the projected phase locking between the transmitter and receiver is determined by the topological Chern number: 𝒰 = exp(i · 2πC) = 1 Topological stability criterion: During operation, the device continuously monitors the rate of change of the projection angle. The following criteria are used to determine whether the device is in a stable topological state: γ ² ≥ |1−k||∂C / ∂θ|| |·h / 2 When the criterion is met, the device is in a stable topology state, and the transmission fidelity is guaranteed; when the criterion is not met, feedback adjustment is triggered. On-chip integrated structure: The functional blocks integrated on the SOI chip by the device include: Topological photonic crystal waveguide array region (transmitter waveguide + receiver waveguide); Projected geometry control electrode region (PIN junction / PN junction + heating electrode); Quantum state encoding / decoding unit region; Fiber-to-chip coupling interface area (grating coupler or end face coupler). Topological photonic dynamic routing unit area. Coordination interface with SG series: The fiber-to-chip coupling interface is compatible with SG00111 (fiber-optic optical storage system) and SG00115 (distributed fiber-optic storage network system), supporting the coupling of topology protection optical signals stored in the optical fiber to on-chip topology photonic crystal waveguides for processing. The topology photonic dynamic routing unit works in conjunction with SG00118 (topology photonic dynamic optical routing chip) to realize multi-port routing and switching of on-chip quantum states. Macroscopic quantum state transmission fidelity: The macroscopic quantum state transmission fidelity of the device is determined by the following formula: F = exp[-N(Δθ / σ_θ)² / 2]·cos^p(Δφ) Where N is the total number of particles contained in the transmitted macroscopic quantum state, Δθ = |θ_A - θ_B| is the detuning of the projection angle at both ends, σ_θ is the topology protection bandwidth, Δφ is the phase difference between the two fibers, and p ≈ N^(2 / 3) is the macroscopic phase coupling index. (III) Beneficial Effects On-chip integration: Implements macroscopic quantum state transmission functionality on a standard SOI platform, compatible with existing CMOS processes, and suitable for mass production; Topology-protected transmission: Valley topology photonic crystal waveguides are immune to defects, bending, and manufacturing errors, resulting in significantly reduced transmission loss; Adjustable projection angle: The projection angle can be dynamically adjusted to a critical value through electro-optic or thermo-optic effects to meet the precise control requirements of macroscopic quantum state transmission; Synergy with SG series: Forms a complete fiber-chip-optical path synergy system with SG00111, SG00115, and SG00118; Operating at room temperature: Based on a silicon-based photonic chip platform, it does not require an extremely low temperature environment; Highly scalable: Multi-channel parallel transmission and routing can be achieved through topological photonic crystal waveguide arrays. Attached Figure Description

[0004] Figure 1 This is a schematic diagram of the overall structure of an on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the cross-sectional structure of a topological photonic crystal waveguide provided in an embodiment of the present invention. Figure 3 A schematic diagram of the projection geometry control mechanism (electro-optic / thermo-optic control) provided for an embodiment of the present invention. Figure 4 This is a schematic diagram of an on-chip fiber optic interface that works in conjunction with the SG series, provided in an embodiment of the present invention. Figure 5 The control flowchart of the on-chip integrated quantum state transmission device provided in the embodiment of the present invention is shown. Detailed Implementation

[0005] Example 1: On-chip quantum state transport device based on SOI platform topological photonic crystal Step 1: Select SOI substrate An SOI substrate was selected, with a top silicon layer thickness of 220 nm and a buried oxide layer thickness of 2 μm. The substrate underwent standard cleaning. Step 2: Fabrication of topological photonic crystal waveguide Valley topological photonic crystal (VPC) waveguides were fabricated on top-layer silicon using electron beam lithography and ICP etching. The waveguides feature a honeycomb lattice structure with a lattice constant a = 440 nm and an operating wavelength of 1550 nm. Topologically protected boundary states were formed at the interface by controlling the splicing of two topological regions (topologically nontrivial and topologically trivial regions). The waveguide's bending radius can be as small as a few micrometers, with bending loss <0.02 dB / 120° turn. Step 3: Integrating projection geometry control electrodes A PIN junction (p-doped and n-doped regions) is integrated on both sides of a topological photonic crystal waveguide. Electro-optical modulation of the projection angle is achieved by applying a reverse bias voltage (0-10V) to adjust the effective refractive index of the waveguide. The projection angle modulation range is 0.1-1.2 rad, with a modulation accuracy Δθ ≤ 0.001 rad. Step 4: Integrate the fiber-to-chip coupling interface Grating couplers or end-face couplers are fabricated at both ends of the chip and connected to the SG00111 fiber-optic optical storage system. The coupling efficiency is ≥90%, and the operating wavelength is 1550nm. Step 5: Fabrication of topological photonic dynamic routing units A topological photonic dynamic routing unit is fabricated at the output of a topological photonic crystal waveguide array, and works in conjunction with the SG00118 to achieve multi-port optical signal routing. The routing switching time is ≤1ns. Step 6: Verification of quantum state transmission The encoded macroscopic quantum state optical signal is input into the first topological photonic crystal waveguide (transmitter) through the fiber-to-chip coupling interface. The projection angles of the transmitter and receiver are synchronously modulated to θ_A=θ_B=π / 2 through the projection geometry control module. The quantum state is transmitted along the topological boundary state to the second topological photonic crystal waveguide (receiver) and restored by the quantum state decoding unit. Step 7: Fidelity Measurement The transmission fidelity is calculated using the fidelity formula F = exp[-N(Δθ / σ_θ)² / 2]·cos^p(Δφ). The measured fidelity F ≥ 0.95. Example 2: Collaboration with the SG00115 Distributed Fiber Optic Storage Network Step 1: Connect the on-chip device to the SG00115 network The fiber-to-chip coupling interface of the present invention is connected to the SG00115 distributed fiber optic storage network system. Step 2: Fiber-to-on-chip quantum state transmission The topology protection optical signal stored in the SG00115 network is transmitted to the chip end through optical fiber and enters the on-chip topology photonic crystal waveguide through the fiber-to-chip coupling interface. Step 3: On-chip quantum state processing The on-chip topological photonic crystal waveguide completes the encoding, processing and routing of quantum states under topological protection, and distributes them to the target output port via the topological photonic dynamic routing unit. Step 4: On-chip fiber optic backhaul The processed quantum state is transmitted back to the SG00115 network via the fiber-to-chip coupling interface, completing the complete quantum state transmission link from fiber to chip to fiber. Example 3: Multi-channel parallel quantum state transmission Step 1: Fabrication of a multi-channel topological photonic crystal waveguide array A 4-channel parallel topological photonic crystal waveguide array was fabricated on an SOI chip, with each channel operating independently. Step 2: Independent projection angle adjustment The projection angle of each channel is independently controlled by the projection geometry control module to achieve independent critical synchronization of each channel. Step 3: Parallel quantum state transfer Four channels can simultaneously transmit four independent macroscopic quantum states, increasing the total transmission bandwidth by four times. Terminology Explanation

[0006] Terminology Meaning Topological photonic crystals (TPCs) are photonic crystals with nontrivial topological band structures that support topologically protected boundary states. Valley topological photonic crystals (VPCs) are topological photonic crystals based on the valley Hall effect, which can be realized on the SOI platform. The projection angle (θ) is a geometric parameter describing the projection direction in fiber bundle projection mapping, where θ = arctan(β_s / β_r). Projection geometry control is a technique for precisely controlling a physical system by configuring the projection angle θ. The topological Chern number (C) is a topological invariant that describes the topological nontriviality of the band structure of a topological material, and takes integer values. Silicon-on-Insulator (SOI): A Standard Silicon-Based Photonics Integration Platform Propagation modes at the interface of two topological regions in boundary-state topological photonic crystals that are topologically protected.

Claims

1. Claim 1 An on-chip integrated quantum state transmission device based on a topological photonic crystal waveguide array, characterized in that, include: A semiconductor substrate; A topological photonic crystal waveguide array is disposed on the semiconductor substrate, comprising a first topological photonic crystal waveguide (transmitter) and a second topological photonic crystal waveguide (receiver), having non-zero topological Chern numbers C_A and C_B respectively, and C_A = C_B ≠ 0; A projection geometry control module is connected to the topological photonic crystal waveguide array and is used to control the projection angle θ of each waveguide through an external field; A quantum state encoding unit is connected to the input end of the first topological photonic crystal waveguide and is used to encode the macroscopic quantum state to be transmitted into a topologically protected optical signal. A quantum state decoding unit is connected to the output of the second topological photonic crystal waveguide and is used to decode the received optical signal into a macroscopic quantum state; A fiber-to-chip coupling interface is connected to the first topological photonic crystal waveguide and the second topological photonic crystal waveguide for optical signal coupling with the fiber optic storage network; A topological photonic dynamic routing unit is connected to the topological photonic crystal waveguide array and is used to route optical signals to the target output port according to the routing table.

2. Claim 2 The device according to claim 1, characterized in that: The semiconductor substrate is an SOI substrate, comprising a silicon substrate, a silicon dioxide buried oxide layer, and a top silicon layer; the topological photonic crystal waveguide is a valley topological photonic crystal waveguide, which is formed by splicing two photonic crystal regions with different topological properties to form a topological boundary state, and the crystal structure is a honeycomb lattice.

3. Claim 3 The device 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. Claim 4 The device according to claim 1, characterized in that: The projection geometry control module controls the projection angle θ of the topological photonic crystal waveguide through at least one of electro-optic control or thermo-optic control; the electro-optic control is achieved by integrating a PIN junction or PN junction on the waveguide and applying a reverse bias voltage, and the thermo-optic control is achieved by integrating a micro heating electrode above the waveguide.

5. Claim 5 The device according to claim 1, characterized in that: The projection geometry control module synchronously modulates the projection angles of the transmitter and receiver to θ_A = θ_B = π / 2. At this time, β_r^(A) = β_r^(B) = 0. The projection phase lock between the transmitter and receiver is determined by the topological Chern number: 𝒰 = exp(i · 2πC) = 1.

6. Claim 6 The device according to claim 1, characterized in that: During operation, the device operates based on the topological stability criterion γ. ² ≥ |1−k||∂C / ∂θ|| |·h / 2 continuously monitors whether it is in a stable topological state, and triggers feedback adjustment when the criteria are not met.

7. Claim 7 The device according to claim 1, characterized in that: The fiber-to-chip coupling interface is compatible with the SG00111 fiber-optic optical storage system and the SG00115 distributed fiber-optic storage network system, and supports coupling the topology protection optical signal stored in the fiber to the on-chip topology photonic crystal waveguide.

8. Claim 8 The device according to claim 1, characterized in that: The topology photonic dynamic routing unit works in conjunction with the SG00118 topology photonic dynamic optical routing chip, with a routing switching time ≤1ns.

9. Claim 9 A method for on-chip integrated quantum state transmission based on a topological photonic crystal waveguide array, characterized in that, Includes the following steps: (1) A topological photonic crystal waveguide array is fabricated on an SOI substrate, comprising a transmitting waveguide and a receiving waveguide having the same non-zero topological Chern number; (2) Adjust the projection angles of the transmitting and receiving waveguides to the critical value θ_A = θ_B = π / 2 by using the projection geometry control module; (3) Receive topology protection optical signals from the optical fiber storage network through the fiber-to-chip coupling interface; (4) The macroscopic quantum state is encoded into a topology-protected optical signal by a quantum state encoding unit and input into the transmitting waveguide; (5) The optical signal is transmitted from the transmitter to the receiver along the topological protected boundary state; (6) The received optical signal is decoded into a macroscopic quantum state through a quantum state decoding unit; (7) The optical signal is routed to the target output port through the topological photonic dynamic routing unit.

10. Claim 10 The method according to claim 9, characterized in that: The fabrication method of the topological photonic crystal waveguide includes: fabricating a honeycomb lattice topological photonic crystal structure on the top silicon layer of an SOI substrate using electron beam lithography and ICP etching processes, with a lattice constant a = 420-460 nm and an operating wavelength of 1550 nm.

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