A macroscopic quantum state transmission device based on a magnetic topological insulator heterojunction and a preparation method thereof

Abstract

The application discloses a macroscopic quantum state transmission device based on a magnetic topological insulator heterojunction and a preparation method thereof. The device comprises a first MnBi2Te4 heterojunction element (a sending end with a non-zero topological Chern number C_A), a second MnBi2Te4 heterojunction element (a receiving end with the same non-zero topological Chern number C_B=C_A), a gate electrode array, a terahertz pulse generating device, a synchronous control system and a quantum state reading system. The gate electrode array applies a gate voltage to project an angle, the terahertz pulse generating device applies a synchronous terahertz pulse to finely project the angle to a critical value θ_A=θ_B=π / 2, and the synchronous control system ensures synchronization at both ends. The MnBi2Te4 heterojunction element comprises an odd number of layers (1-50 seven-layer) MnBi2Te4 thin film and upper and lower AlO x protective layers, and an AlO x -MnBi2Te4-AlO x sandwich heterojunction structure. The application takes MnBi2Te4 intrinsic magnetic topological insulator as a material platform, utilizes the characteristics of a non-zero topological Chern number and a controllable projection angle, and realizes an engineering macroscopic quantum state topological transmission, which is suitable for scenarios such as interstellar quantum communication and quantum network interconnection.

Description

Technical Field

[0001] This invention relates to the fields of quantum information transmission technology and topological materials technology, specifically to a macroscopic quantum state transmission device based on a magnetic topological insulator heterojunction and its fabrication method. This invention can be applied to fields such as instantaneous macroscopic quantum state transmission, interstellar quantum communication, quantum network node interconnection, distributed quantum computing, and quantum-enhanced navigation systems, and is particularly suitable for application scenarios that realize macroscopic quantum state topological transmission based on a magnetic topological insulator material platform. Background Technology

[0002] Macroscopic quantum state transfer (stargate) refers to the transfer of a large number of particles ( The technology of instantaneously transmitting the collective quantum state of macroscopic objects (and above) from one point in space to another. The core condition for realizing macroscopic quantum state transmission is that the topological materials of the transmitting and receiving ends have the same non-zero topological Chern number. ), and the projection angles at both ends reach the critical value simultaneously ( , Therefore, finding a suitable topological material platform is key to realizing the interplanetary gate. MnBi₂Te₄ is an intrinsic antiferromagnetic topological insulator and is currently the only confirmed quantum anomalous Hall effect material with bulk antiferromagnetic order. It combines intrinsic topological electronic states and intrinsic magnetic order, providing a unique platform for studying the interaction between magnetism and topology. By manipulating its magnetic properties, exotic quantum phenomena such as the quantum anomalous Hall effect, axion insulator states, and Majorana fermions can be observed. MnBi₂Te₄ has become a multifunctional platform for exploring various topological quantum states. However, current research on MnBi₂Te₄ materials mainly focuses on characterizing fundamental physical properties and observing the quantum anomalous Hall effect, and has not yet been applied to macroscopic quantum state transmission devices. The existing technology mainly suffers from the following problems: (i) Lack of suitable material platforms for macroscopic quantum state transport Current macroscopic quantum state transport schemes remain at the theoretical level, lacking concrete material platforms with non-zero topological Chern numbers and tunable projection angles. The intrinsic magnetic topological properties of MnBi₂Te₄ make it an ideal candidate material, but it has not yet been systematically applied to the design and fabrication of macroscopic quantum state transport devices. (ii) Lack of engineered preparation schemes for MnBi2Te4 heterojunctions The topological properties of MnBi₂Te₄ are influenced by the number of layers, stacking arrangement, and surface state. Odd-layered and even-layered MnBi₂Te₄ exhibit different topological phases: odd-layered MnBi₂Te₄ is in the quantum anomalous Hall phase (…). Even-numbered layers are axion insulator states ( Existing fabrication methods (such as mechanical exfoliation) are insufficient for achieving the fabrication of heterojunctions with controllable thickness, large area, and high quality. Therefore, there is an urgent need for engineered heterojunction fabrication methods for macroscopic quantum state transport devices. (iii) Lack of projection angle control scheme based on MnBi2Te4 Macroscopic quantum state transport requires precise control of the projection angle of the topological material. To the critical value Current research on MnBi2Te4 mainly focuses on adjusting the topological properties by controlling the carrier density and displacement field through gate voltage, but an engineering scheme to control the projection angle to the critical state has not yet been realized. (iv) Lack of stability guarantee for MnBi2Te4 Chern number The presence of intrinsic antisite defects in MnBi₂Te₄ affects the stability of its topological properties. Macroscopic quantum state transport requires… To maintain a constant topological number during transmission, existing solutions lack proactive monitoring methods for the stability of the topological number. To address the above problems, this invention provides a macroscopic quantum state transport device based on a magnetic topological insulator heterojunction 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 transport schemes, such as the lack of suitable material platforms, the lack of engineering preparation schemes for MnBi2Te4 heterojunctions, the lack of projection angle control schemes, and the lack of Chern number stability guarantees. It provides a macroscopic quantum state transport device and its preparation method based on a magnetic topological insulator heterojunction, using MnBi2Te4 multilayer heterojunction as the core material platform to realize engineeringable macroscopic quantum state topological transport. (II) Technical Solution This invention provides a macroscopic quantum state transport device based on a magnetic topological insulator heterojunction, characterized in that it comprises: A first MnBi2Te4 heterojunction device (transmitter) comprises a MnBi2Te4 thin film and protective layers on its upper and lower surfaces, having a non-zero topological Chern number. ; A second MnBi₂Te₄ heterojunction element (receiver) comprises a MnBi₂Te₄ thin film and protective layers on its upper and lower surfaces, and has the same non-zero topological Chern number as the first MnBi₂Te₄ heterojunction element. ; A gate electrode array is disposed on the upper surface of the first MnBi2Te4 heterojunction element and the second MnBi2Te4 heterojunction element, and is used to apply gate voltage to regulate the projection angle; A terahertz pulse generator is connected to the first MnBi2Te4 heterojunction element and the second MnBi2Te4 heterojunction element to apply a synchronous terahertz pulse to modulate the projection angle to a critical value. A synchronization control system, connected to the gate electrode array and the terahertz pulse generator, is used to ensure that the projection angles of the transmitting and receiving ends are synchronized to a critical value. ; A quantum state readout system, connected to the second MnBi2Te4 heterojunction element, is used to measure changes in the projection weights at the receiving end to confirm successful quantum state transmission. Core Materials Platform: The MnBi2Te4 heterojunction element comprises: A substrate (sapphire, Si(111) or SrTiO3); A MnBi2Te4 thin film is disposed on the substrate and has a non-zero topological Chern number; Upper protective layer (AlO) x Or hexagonal boron nitride), disposed on the upper surface of the MnBi2Te4 thin film; First protective layer (AlO) x Or hexagonal boron nitride), disposed between the lower surface of the MnBi2Te4 thin film and the substrate. The MnBi₂Te₄ thin film has an odd number of seven layers (1, 3, 5, …, 2m+1 SL) to ensure a non-zero topological Chern number. . The thickness of the upper and lower protective layers is 2-10 nm. Projection angle adjustment mechanism: The projection angle Defined as: The gate electrode array is activated by applying a gate voltage. By controlling the carrier density and band structure of MnBi2Te4 thin films, the projection angle can be changed. The terahertz pulse generator further modulates the projection angle to a critical value by applying pulses with a frequency of 0.1-10 THz. The electric field component of the terahertz pulse modulates the refractive index and topological surface state dispersion of the MnBi2Te4 thin film through optical rectification or photoconductivity. Critical synchronization condition: The synchronization control system synchronously modulates the projection angles of the transmitting and receiving ends to: At this point, the projected phase locking between the transmitter and receiver is determined by the topological Chern number: Macroscopic quantum state transmission fidelity: The macroscopic quantum state transmission fidelity of the device is determined by the following formula: in The total number of particles contained in the macroscopic object being transmitted. This represents the detuning of the projection angles at both ends. For topology protection bandwidth, The phase difference between the two ends of the fiber. This is the macroscopic phase coupling index. (III) Beneficial Effects Mature material platform: MnBi2Te4 is currently the only confirmed intrinsic antiferromagnetic topological insulator, and its topological properties have been extensively studied and verified, indicating high material maturity; Adjustable topological Chern number: By controlling the number of layers (odd number of layers) of the MnBi2Te4 thin film Even-numbered layers ), which allows for precise control of the topological Chern number; Double-sided protection enhances stability: AlO x Alternatively, double-sided encapsulation with hexagonal boron nitride can protect MnBi2Te4 films from oxidation and contamination, significantly enhancing the stability of the topological quantum phase; Combined control of gate voltage and terahertz pulse: gate voltage enables coarse adjustment of the projection angle, while terahertz pulse enables fine adjustment of the projection angle to the critical state; Compatible with existing semiconductor processes: The MnBi2Te4 heterojunction can be fabricated on a standard substrate using molecular beam epitaxy, which is compatible with existing semiconductor processes and suitable for large-scale fabrication. Attached Figure Description

[0004] Figure 1 This is a schematic diagram of the overall structure of a macroscopic quantum state transmission device based on a magnetic topological insulator heterojunction, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the layered structure of the MnBi2Te4 heterojunction element provided in an embodiment of the present invention. Figure 3 A schematic diagram of the projection angle control mechanism (gate voltage + terahertz pulse) provided for an embodiment of the present invention. Figure 4 A control flowchart for a macroscopic quantum state transmission device provided in an embodiment of the present invention. Detailed Implementation

[0005] Example 1: Macroscopic quantum state transport device based on MnBi2Te4 multilayer heterojunction Step 1: Select substrate and clean it Sapphire (Al2O3) or Si(111) substrates with a thickness of 500 μm were selected. The substrates were subjected to standard cleaning: ultrasonic cleaning in acetone, ethanol and deionized water for 15 minutes in sequence, and then dried with nitrogen before being sent to the ultra-high vacuum molecular beam epitaxy system. Step 2: Growth of MnBi2Te4 thin film MnBi₂Te₄ thin films were grown on a substrate using molecular beam epitaxy. The growth conditions were as follows: Substrate temperature: 180-250°C Mn source temperature: 600-700°C Bi source temperature: 450-550°C Te source temperature: 300-400°C Mn / Bi flux ratio: Strictly controlled to achieve stoichiometry The growth process can be divided into the following sub-steps: (1) A 5 nm Bi2Te3 buffer layer was grown on the substrate to improve the crystal quality of the MnBi2Te4 film; (2) Mn-Te and Bi-Te layers were alternately deposited on the buffer layer, and the film thickness was precisely controlled to seven seven-layer (SL) (odd number of layers) by controlling the number of deposition cycles. ); (3) Each seven-layer structure contains one Mn-Te bilayer and two Bi-Te ternary layers, with a total thickness of approximately 1.4 nm; (4) After growth, 5 nm of AlO2 was deposited on the surface of the MnBi2Te4 film. x Protective layer. Step 3: Prepare a double-sided protected heterojunction (1) Before growing the MnBi2Te4 thin film, a 3 nm layer of AlO2 was pre-deposited on the substrate. x As a lower protective layer; (2) After the growth of MnBi2Te4 film, 5 nm of AlO2 was deposited on the upper surface of the film. x As an upper protective layer; (3) Formation of AlO x -MnBi2Te4-AlO x The sandwich heterojunction structure and double-sided encapsulation protect MnBi2Te4 from oxidation and environmental degradation. Step 4: Integrating the gate electrode array (1) In AlO xTi / Au gate electrodes (5 nm Ti + 50 nm Au) are deposited on the surface of the upper protective layer, and the electrode pattern is defined by electron beam lithography; (2) The electrode pattern is an array structure, with each electrode corresponding to a region of the MnBi2Te4 thin film, thereby achieving local projection angle control; (3) Deposit Ti / Au back gate electrode on the back side of the substrate. Step 5: Integrate the terahertz antenna array (1) Integrating a terahertz antenna array (log-periodic antenna or dipole antenna array) on both sides of a MnBi2Te4 thin film. (2) The operating frequency range of the terahertz antenna is 0.1-10 THz, which is used to apply synchronous terahertz pulse modulation projection angle to the critical value. Step 6: Configure the synchronization control system (1) The synchronous control system is connected to the gate electrode array and the terahertz pulse generator; (2) The system includes a high-precision timing control module with a timing synchronization accuracy of ≤1ps; (3) The control process is as follows: First, the projection angle is coarsely adjusted to close to π / 2 by the gate voltage, and then the projection angle is finely adjusted to π / 2 by the terahertz pulse. Step 7: Verification of macroscopic quantum state transmission (1) The macroscopic object to be transmitted (including A molecular cluster of 10 atoms is placed on the surface of the MnBi2Te4 thin film at the transmitting end, so that it forms a strong coupling with the topological surface state; (2) By simultaneously applying gate voltage and terahertz pulse to both ends through a synchronous control system, the projection angles at both ends are synchronously modulated to the critical value. ; (3) At this time The quantum state is frozen in time, and the macroscopic quantum state is instantaneously reconstructed at the receiving end through the common topological branch of the high-dimensional fiber bundle; (4) The successful transmission of the macroscopic quantum state is confirmed by measuring the change of the projection weight at the receiving end through the quantum state readout system. Step 8: Fidelity Measurement According to the fidelity formula Calculate transmission fidelity. When and At that time, fidelity The transmission was deemed successful. Example 2: Preparation method of double-sided protected heterojunction Step 1: Preparation of MnBi2Te4 thin films Same as steps 1-2 in Example 1. Step 2: Deposit the lower protective layer Prior to the growth of the MnBi2Te4 thin film, a 3-5 nm layer of AlO2 was pre-deposited on the substrate. x Alternatively, hexagonal boron nitride can be used as the lower protective layer. Step 3: Deposit a protective layer After the MnBi2Te4 film growth was completed, 3-5 nm of AlO2 was deposited on the upper surface of the film. x Alternatively, hexagonal boron nitride can be used as the upper protective layer. Step 4: Formation of sandwich heterojunctions A protective layer-MnBi2Te4-protective layer sandwich heterojunction structure is formed, and double-sided encapsulation protects MnBi2Te4 from oxidation and environmental degradation. Terminology Explanation

[0006] Terminology Meaning MnBi₂Te₄ is an intrinsic antiferromagnetic topological insulator and is currently the only confirmed quantum anomalous Hall effect material with bulk antiferromagnetic order. The basic structural unit of seven-layer (SL) MnBi₂Te₄ consists of one Mn-Te bilayer and two Bi-Te ternaries, with a thickness of approximately 1.4 nm. The topological Chern number (C) is a topological invariant describing the topological nontriviality of the band structure of a topological material. For odd-numbered layers of MnBi₂Te₄, C = ±1. The projection angle (θ) is a geometric parameter describing the projection direction in fiber bundle projection mapping, where θ = arctan(β_s / β_r). Heterojunctions are structures composed of layers of different materials; in this invention, AlO is used. x -MnBi2Te4-AlO x sandwich structure Molecular beam epitaxy (MBE) is a technique for depositing thin films using molecular beams under ultra-high vacuum conditions.

Claims

1. A macroscopic quantum state transport device based on a magnetic topological insulator heterojunction, characterized in that, include: A first MnBi2Te4 heterojunction device (transmitter) comprising a MnBi2Te4 thin film having a non-zero topological Chern number. ; A second MnBi2Te4 heterojunction element (receiver) comprises a MnBi2Te4 thin film and has the same non-zero topological Chern number as the first MnBi2Te4 heterojunction element. ; A gate electrode array is disposed on the surface of the first MnBi2Te4 heterojunction element and the second MnBi2Te4 heterojunction element, and is used to apply a gate voltage to regulate the projection angle; A terahertz pulse generator is connected to the first MnBi2Te4 heterojunction element and the second MnBi2Te4 heterojunction element to apply a synchronous terahertz pulse to modulate the projection angle to a critical value. A synchronization control system, connected to the gate electrode array and the terahertz pulse generator, is used to ensure that the projection angles of the transmitting and receiving ends are synchronized to a critical value. ; A quantum state readout system, connected to the second MnBi2Te4 heterojunction element, is used to measure changes in the projection weights at the receiving end to confirm successful quantum state transmission.

2. The apparatus according to claim 1, characterized in that: The MnBi₂Te₄ heterojunction element further includes a protective layer disposed on the upper and lower surfaces of the MnBi₂Te₄ thin film, the material of which is Al₂O₃. x Alternatively, hexagonal boron nitride with a thickness of 2-10 nm.

3. The apparatus according to claim 1, characterized in that: The MnBi₂Te₄ thin film has an odd number of seven layers (1, 3, 5, …, 2m+1 SL) to ensure a non-zero topological Chern number. .

4. The apparatus according to claim 1, characterized in that: The terahertz pulse has a frequency range of 0.1-10 THz and is used to modulate the projection angle to a critical value. .

5. The apparatus according to claim 1, characterized in that: The timing synchronization accuracy of the synchronous control system is ≤1ps.

6. The apparatus according to claim 1, characterized in that: The projection angle Defined as , The critical synchronization condition is: , .

7. The apparatus according to claim 1, characterized in that: The fidelity of the macroscopic quantum state transmission is determined by Confirmed, among which , For topology protection bandwidth, For fiber phase difference, .

8. A macroscopic quantum state transport method based on a magnetic topological insulator heterojunction, characterized in that, Includes the following steps: (1) Provide a first MnBi2Te4 heterojunction element (transmitter) and a second MnBi2Te4 heterojunction element (receiver), both having the same non-zero topological Chern number. ; (2) The macroscopic object to be transmitted is placed at the transmitting end, so that its collective wave function and the projection weight of the transmitting end form a coherent superposition; (3) Apply gate voltage through the gate electrode array to coarsely adjust the projection angles of the transmitting and receiving ends. and to near ; (4) Apply a synchronized terahertz pulse through a terahertz pulse generator and fine-tune the projection angles of the transmitting and receiving ends to the critical value. ,make ; (5) The collective wave function of the macroscopic object at the transmitting end is instantaneously reconstructed at the receiving end through the common topological branch of the high-dimensional fiber bundle; (6) The successful transmission of the quantum state is confirmed by measuring the change of the projection weight at the receiving end through the quantum state readout system.

9. The method according to claim 8, characterized in that: The method for preparing the MnBi2Te4 heterojunction device in step (1) includes: growing a MnBi2Te4 thin film on a substrate using molecular beam epitaxy.

10. The method according to claim 8, characterized in that: The synchronous application of the terahertz pulse in step (4) is controlled by a synchronization control system, with a timing synchronization accuracy of ≤1ps.

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