Method for regulating and controlling boundary topological property of silicon waveguide quantum system and generating topological two-photon state by pump light

Abstract

The invention discloses a method for regulating and controlling the boundary topological property of a silicon waveguide quantum system through pump light and generating a topological two-photon state, which combines the nonlinearity of a silicon waveguide material and a Su-Schriffer-Heeger (SSH) model of a silicon waveguide space structure, and realizes the topological property of the boundary state on a silicon waveguide chip by regulating the intensity of the pump light input into the silicon waveguide chip. By improving the intensity of input pump light to exceed a certain threshold value, the coupling between the silicon waveguide at the pump light input position and the adjacent silicon waveguide is enhanced, so that a boundary effect is presented at the input position; a system boundary is designed to be long-long type waveguide coupling, pump light is input at a center waveguide of the long-long boundary, and the intensity of the pump light is adjusted to exceed a certain threshold value, so that a two-photon state of topology protection is output at a waveguide chip.

Description

Technical Field

[0001] The present invention belongs to the field of quantum technology, and particularly relates to a method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light and generating a topological two-photon state. Background Art

[0002] Quantum topological materials have received extensive attention due to their potential applications in quantum computing and quantum information processing. The unique properties of these materials, such as topologically protected edge states and high fault tolerance, provide new ways to realize stable qubits. However, there are some limitations and challenges in the design, preparation, and analysis methods of topological materials. Traditional topological materials usually rely on complex chemical synthesis or physical preparation processes, which are not only costly but also difficult to achieve precise control. When realizing topological phase transitions in existing topological materials, precise external control is usually required, such as precise temperature or chemical potential regulation, which may be difficult to achieve in practical applications. In addition, the topological properties of these materials may be sensitive to environmental changes, resulting in insufficient stability and robustness. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light and generating a topological two-photon state. By combining the nonlinearity of the silicon waveguide material and the Su-Schrieffer–Heeger (SSH) model of the silicon waveguide spatial structure, the topological properties of the edge states on the silicon waveguide chip are realized by adjusting the intensity of the pump light input into the silicon waveguide chip; by increasing the intensity of the input pump light to exceed a certain threshold, the coupling between the silicon waveguide at the pump light input position and its adjacent silicon waveguides will be enhanced, resulting in an edge effect at the input position; by designing the system boundary as a "long-long" type waveguide coupling, inputting pump light at the center waveguide of the "long-long" boundary, and adjusting the pump light intensity to exceed a certain threshold, a topologically protected two-photon state is output on the waveguide chip.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0005] Step 1: Regulating the boundary topological properties of the silicon waveguide quantum system by pump light;

[0006] Step 1-1: Preparing a silicon waveguide chip with an SSH lattice structure, where the inter-cell coupling uses a nonlinear material;

[0007] Step 1-2: Analyzing the energy band structure and topological properties of the silicon waveguide chip under the condition of no light field;

[0008] Step 1-3: Placing the silicon waveguide chip under light intensity and analyzing the energy band structure and topological properties of the silicon waveguide chip;

[0009] Step 2: Analyze the impact of a single-point silicon waveguide irradiated by a strong light field on the chip;

[0010] Step 2-1: Fabricate a silicon waveguide chip with an SSH lattice structure;

[0011] Step 2-2: Select the middle waveguide of the SSH silicon waveguide chip and input pump light;

[0012] Step 2-3: Analyze the evolution of the pump light in the silicon waveguide chip and observe the existence of edge states;

[0013] Step 2-4: Increase the light intensity of the pump light, analyze the existence of edge states, and the evolution of topological light at the boundary;

[0014] Step 3: Generate topological two-photon states;

[0015] Step 3-1: Fabricate a silicon waveguide chip with an SSH lattice structure and construct the middle waveguide into a "long-long" defect type;

[0016] Step 3-2: Select the leftmost waveguide of the silicon waveguide chip with a "long-long" defect and input pump light;

[0017] Step 3-3: Analyze the evolution of the pump light in the silicon waveguide chip and observe the existence of edge states;

[0018] Step 3-4: Increase the light intensity of the pump light, analyze the existence of topological edge states, and the evolution of topological light at the boundary;

[0019] Step 3-5: Analyze the existence of two-photon states in the topological edge state and the evolution of topological two-photon states at the boundary.

[0020] Preferably, the principle of the method for the pump light to regulate the boundary topological properties of the silicon waveguide quantum system and generate topological two-photon states is realized based on the nonlinearity of the silicon waveguide material, including the Kerr effect of the silicon waveguide, that is, the coupling coefficient between waveguides is affected by the input light intensity, and the pump light is converted into signal light photons and idler light photons by using the four-wave mixing process;

[0021] For the SSH lattice, the Kerr effect will generate a nonlinear term, which affects the inter-cell coupling coefficient of the SSH model. By continuously increasing the light intensity, the inter-cell coupling coefficient of the SSH model is increased, and then the boundary at the light input lattice shows different topological properties;

[0022] The Hamiltonian describing the system is:

[0023] H = H p +H s +H i +H NL (1)

[0024]

[0025] where H p , H s , H i represent the Hamiltonians of the pump light, signal light, and idler light during the evolution process, respectively, where represents the intracell coupling coefficients of the pump light, signal light, and idler light, represents the original intercell coupling coefficients of the pump light, signal light, and idler light, α(|a 1,n | 2 +|a 2,n-1 | 2 ) represents the influence of the Kerr effect on the intercell coupling coefficient, α represents the Kerr nonlinear term parameter, (|a 1,n | 2 +|a 2,n-1 | 2 ) represents the amplitude of the corresponding photon of the corresponding dimer; H NL represents the mutual conversion between the pump light (Pump) and the two-photon pair (signal and idler) under the SFWM effect, and γ represents the SFWM nonlinear term parameter.

[0026] Preferably, the SSH lattice structure is composed of 50 unit cells to form a system with 102 lattice points; the intracell distance t s is designed to be less than the intercell distance t l , so that the intracell coupling is greater than the intercell coupling, and the system is in a topologically trivial state, that is, the topological number winding number w = 0.

[0027] Preferably, the "long-long" defect type is: composed of 50 unit cells on the left and 50 unit cells on the right, and the left and right lattice point chains and the middle lattice points form a "long-long" defect.

[0028] A computer program that causes a computer to execute the method for regulating the boundary topological properties of a pump light-controlled silicon waveguide quantum system and generating a topological two-photon state.

[0029] An electronic device, comprising: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device executes the method for regulating the boundary topological properties of a pump light-controlled silicon waveguide quantum system and generating a topological two-photon state.

[0030] A computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the method for regulating the boundary topological properties of a pump light-controlled silicon waveguide quantum system and generating a topological two-photon state.

[0031] A chip, comprising: a processor for calling and running a computer program from a memory, so that a device installed with the chip executes the method for regulating the topological properties of the boundary of the pumped optical silicon waveguide quantum system and generating a topological two-photon state.

[0032] A computer program product, the computer program product comprising a computer storage medium storing a computer program, the computer program comprising instructions executable by at least one processor, and when the instructions are executed by the at least one processor, implementing the method for regulating the topological properties of the boundary of the pumped optical silicon waveguide quantum system and generating a topological two-photon state.

[0033] The beneficial effects of the present invention are as follows:

[0034] (1) In the present invention, the regulation of the topological defects of the chip can realize the reuse of the quantum silicon-based waveguide chip;

[0035] (2) In the present invention, by dynamically regulating the topological properties at the defect of the chip, a new transmission channel is provided for information processing on the chip, which can be used for secure communication. Description of the Drawings

[0036] Figure 1 It is a schematic diagram of a silicon waveguide of an SSH lattice, and the arrow position is the input position of the pump light.

[0037] Figure 2 It is the energy band diagram of the SSH chip.

[0038] Figure 3 It is the energy band diagram of the SSH chip under a high optical field (intensity 8).

[0039] Figure 4 It is Figure 3 The schematic diagram of the distribution of two topological edge states in

[0040] Figure 5 It is the schematic diagram of the change of the energy band diagram of the SSH chip with the intensity of the input optical field.

[0041] Figure 6 It is the schematic diagram of the evolution on the silicon waveguide chip after inputting the pump light (intensity 1) into the silicon waveguide with an SSH lattice.

[0042] Figure 7 It is the schematic diagram of the evolution on the silicon waveguide chip after inputting a high-intensity pump light (intensity 18) into the silicon waveguide with an SSH lattice.

[0043] Figure 8 It is the schematic diagram of a silicon waveguide of an SSH lattice with a "long-long" defect, and the arrow position is the input position of the pump light.

[0044] Figure 9It is a schematic diagram of the evolution on a silicon waveguide chip after the pump light is input into a silicon waveguide with a "long-long" defect in an SSH lattice;

[0045] Figure 10 It is a schematic diagram of the evolution on a silicon waveguide chip after a high-intensity pump light is input into a silicon waveguide with a "long-long" defect in an SSH lattice;

[0046] Figure 11 It is a schematic diagram of the evolution of the generated two-photon entangled state after a high-intensity pump light is input into a silicon waveguide with a "long-long" defect in an SSH lattice. Detailed implementation manners

[0047] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0048] The object of the present invention is to provide a method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light and generating a topological two-photon state.

[0049] The present invention is implemented as follows. The method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light combines the nonlinearity of the silicon waveguide material and the Su-Schrieffer–Heeger (SSH) model of the silicon waveguide spatial structure. By adjusting the intensity of the pump light input into the silicon waveguide chip, the topological properties of the boundary states on the silicon waveguide chip are realized; by increasing the intensity of the input pump light to exceed a certain threshold, the coupling between the silicon waveguide at the pump light input position and its adjacent silicon waveguides will be enhanced, so that a boundary effect appears at the input position; by artificially designing the system boundary as a "long-long" type waveguide coupling, inputting pump light at the center waveguide of the "long-long" boundary, and adjusting the pump light intensity to exceed a certain threshold, a topologically protected two-photon state is output on the waveguide chip.

[0050] The principle of the present invention is realized based on the nonlinearity of the silicon waveguide material, including the Kerr effect of the silicon waveguide, that is, the coupling coefficient between waveguides is affected by the input light intensity, and the pump light is converted into signal light (Signal) photons and idler photons by using the four-wave mixing process. Taking the SSH lattice as an example, the Kerr effect will generate a nonlinear term that affects the inter-cell coupling coefficient of the SSH model. The inter-cell coupling coefficient of the SSH model can be increased by continuously increasing the light intensity, thereby making the boundary at the light input lattice point exhibit different topological properties.

[0051] The Hamiltonian describing the system is:

[0052] H = H p + H s + H i + H NL (1)

[0053]

[0054] Among them, H p , H s , H i respectively represent the Hamiltonians of the pump light, signal light, and idler light during the evolution process. Among them represents the intracell coupling coefficients of the pump light, signal light, and idler light represents the original intercell coupling coefficients of the pump light, signal light, and idler light. α(|a 1,n | 2 + |a 2,n-1 | 2 ) represents the influence of the Kerr effect on the intercell coupling coefficient. α represents the Kerr nonlinear term parameter. (|a 1,n | 2 + |a 2,n-1 | 2 ) represents the amplitude of the corresponding photon of the corresponding dimer. H NL represents the mutual conversion between the pump light (Pump) and the two-photon pair (signal and idler) under the SFWM effect. γ represents the SFWM nonlinear term parameter.

[0055] A method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light, specifically including the following steps:

[0056] Step 1: Fabricate a silicon waveguide chip with an SSH lattice structure, where the intercell coupling uses a nonlinear material.

[0057] Step 2: Analyze the energy band structure and topological properties of the chip under the condition of no light field;

[0058] Step 3: Place the silicon waveguide chip under a strong light intensity and analyze its energy band structure and topological properties;

[0059] Furthermore, analyze the influence of a single-point silicon waveguide irradiated by a strong light field on the chip;

[0060] Step 1: Fabricate a silicon waveguide chip with an SSH lattice structure, where the difference between the "long" and "short" coupling coefficients needs to be appropriate.

[0061] Step 2: Select an SSH silicon waveguide chip in the relatively middle waveguide and input the pump light.

[0062] Step 3: Analyze the evolution of the pump light in the silicon waveguide chip and observe whether the boundary state exists.

[0063] Step 4: Increase the light intensity of the pump light, analyze the existence of the boundary state, and the evolution of the topological light at the boundary.

[0064] Furthermore, a method for generating a topological two-photon state by modulating the topological properties of the boundary of a silicon waveguide quantum system with pump light specifically includes the following steps:

[0065] Step 1: Prepare a silicon waveguide chip with an SSH lattice structure and construct the middle waveguide into the "long-long" defect type.

[0066] Step 2: Input pump light at the waveguide at the leftmost end of the silicon waveguide chip with the "long-long" defect.

[0067] Step 3: Analyze the evolution of the pump light in the silicon waveguide chip and observe whether there is a boundary state.

[0068] Step 4: Increase the light intensity of the pump light, analyze the existence of the topological boundary state, and the evolution of the topological light at the boundary.

[0069] Step 5: Analyze the existence of the two-photon state in the topological boundary state and the evolution of the topological two-photon state at the boundary.

[0070] Example:

[0071] The first part: The topological property modulation scheme of the silicon waveguide chip, and the complete steps of the method of the present invention are as follows:

[0072] Step 1: Prepare a silicon waveguide chip with an SSH lattice structure, where the inter-cell coupling uses a nonlinear material, as shown in Figure 1 .

[0073] Step 2: Analyze the energy band structure and topological properties of the chip under the condition of no light field, as shown in Figure 2 ;

[0074] Step 3: Place the silicon waveguide chip under a strong light intensity and analyze its energy band structure and topological properties, as shown in Figures 3 to 5 ;

[0075] Furthermore, analyze the influence of a single-point silicon waveguide irradiated by a strong light field on the chip;

[0076] Step 1: Design a silicon waveguide chip with an SSH lattice. The SSH lattice model we designed selects 50 unit cells to form a system with 102 lattice points. Here, the intra-cell distance t s is less than the inter-cell distance t l , so that the intra-cell coupling is greater than the inter-cell coupling, and the whole system is in a topologically trivial state (topological number winding number w = 0), as shown in Figure 1 .

[0077] Step 2: Input pump light at the arrow shown in Figure 1 , study the evolution of the pump light on the silicon waveguide chip, and find the diffusion behavior of the pump light on the SSH lattice of the silicon waveguide, as shown in Figure 6 .

[0078] Step 3: Gradually increase the pump light intensity at the arrow shown in Figure 1 to study the evolution of the pump light on the silicon waveguide chip, and it is found that the pump light exhibits boundary localized state behavior on the SSH lattice points of the silicon waveguide, as shown in Figure 7 .

[0079] Part II: This scheme proposes a simple, effective, and low-cost method for preparing two-photon entangled states. The specific implementation steps are as follows:

[0080] Step 1: Design a silicon waveguide chip with an SSH lattice structure, and construct the middle waveguide into a "long-long" defect type, that is, the left side is composed of 50 unit cells, the right side is composed of 50 unit cells, and the left and right lattice chains and the middle lattice form a "long-long" defect, as shown in Figure 8 .

[0081] Step 2: Select the waveguide at the leftmost end of the "long-long" defect of the silicon waveguide chip and input pump light, as shown by the arrow in Figure 8 .

[0082] Step 3: Analyze the evolution of the pump light in the silicon waveguide chip with a "long-long" defect, and it is found that the pump light input at the leftmost waveguide of the "long-long" defect does not excite topological edge states, as shown in Figure 9 .

[0083] Step 4: Increase the light intensity of the pump light and analyze the evolution of the pump light in the silicon waveguide chip with a "long-long" defect. It is found that the high-intensity pump light input at the leftmost waveguide of the "long-long" defect changes the type of the defect and excites topological edge states, and there are localized edge states in the evolution, as shown in Figure 10 .

[0084] Step 5: Analyze the generation of two-photon entangled states during the evolution when high-intensity pump light is input into the leftmost waveguide of the "long-long" defect of the silicon waveguide chip. It is found that the high-intensity pump light input at the leftmost waveguide of the "long-long" defect changes the type of the defect and excites topological edge states, and then generates topologically protected two-photon entangled states, as shown in Figure 11 .

Claims

1. A method for regulating the boundary topological properties of a silicon waveguide quantum system by pump light and generating a topological two-photon state, characterized in that, It includes the following steps: Step 1: The pump light regulates the boundary topological properties of the silicon waveguide quantum system; Step 1-1: Fabricate a silicon waveguide chip with an SSH lattice structure, where the inter-cell coupling uses a nonlinear material; Step 1-2: Analyze the energy band structure and topological properties of the silicon waveguide chip under the condition of no light field; Step 1-3: Place the silicon waveguide chip under light intensity and analyze the energy band structure and topological properties of the silicon waveguide chip; Step 2: Analyze the influence of strong light field irradiation on a single-point silicon waveguide on the chip; Step 2-1: Fabricate a silicon waveguide chip with an SSH lattice structure; Step 2-2: Select the SSH silicon waveguide chip in the middle waveguide and input pump light; Step 2-3: Analyze the evolution of the pump light in the silicon waveguide chip and observe whether the boundary state exists; Step 2-4: Increase the light intensity of the pump light, analyze the existence of the boundary state, and the evolution of the topological light at the boundary; Step 3: Generate topological two-photon states; Step 3-1: Fabricate a silicon waveguide chip with an SSH lattice structure and construct the middle waveguide into a "long-long" defect type; Step 3-2: Select the leftmost waveguide of the silicon waveguide chip with a "long-long" defect and input pump light; Step 3-3: Analyze the evolution of the pump light in the silicon waveguide chip and observe whether the boundary state exists; Step 3-4: Increase the light intensity of the pump light, analyze the existence of the topological boundary state, and the evolution of the topological light at the boundary; Step 3-5: Analyze the existence of two-photon states in the topological boundary state and the evolution of topological two-photon states at the boundary.

2. A method for modulating the boundary topological properties of a silicon waveguide quantum system by pump light and generating a topological two-photon state according to claim 1, characterized in that The principle of the method for the pump light to regulate the boundary topological properties of the silicon waveguide quantum system and generate topological two-photon states is realized based on the nonlinearity of the silicon waveguide material, including the Kerr effect of the silicon waveguide, that is, the coupling coefficient between waveguides is affected by the input light intensity, and the pump light is converted into signal light photons and idler light photons by using the four-wave mixing process; For the SSH lattice, the Kerr effect will generate a nonlinear term that affects the inter-cell coupling coefficient of the SSH model. By continuously increasing the light intensity, the inter-cell coupling coefficient of the SSH model is increased, and then the boundary at the light input lattice point exhibits different topological properties; The Hamiltonian describing the system is: H = H p +H s +H i +H NL (1) where H p , H s , H i represent the Hamiltonians of the pump light, signal light, and idler light during the evolution process, respectively, where represents the intracell coupling coefficients of the pump light, signal light, and idler light, represents the original intercell coupling coefficients of the pump light, signal light, and idler light, α(|a 1,n | 2 +|a 2,n-1 | 2 ) represents the influence of the Kerr effect on the intercell coupling coefficient, α represents the Kerr nonlinear term parameter, (|a 1,n | 2 +|a 2,n-1 | 2 ) represents the amplitude of the corresponding photon of the corresponding dimer; H NL represents the mutual conversion of the pump light (Pump) and the two-photon pair (signal and idler) under the SFWM effect, and γ represents the SFWM nonlinear term parameter.

3. A method for modulating the boundary topological properties of a silicon waveguide quantum system by a pump light and generating a topological two-photon state according to claim 2, characterized in that, The SSH lattice structure is composed of 50 unit cells, forming a system with 102 lattice points; the intra-cell distance t is designed. s is less than the inter-cell distance t l , such that the intra-cell coupling is greater than the inter-cell coupling, and the system is in a topologically trivial state, i.e., the topological number winding number w = 0.

4. A method for modulating the boundary topological property of a silicon waveguide quantum system by a pump light and generating a topological two-photon state according to claim 3, characterized in that The "long-long" defect type is: composed of 50 unit cells on the left, composed of 50 unit cells on the right, and the left and right lattice chains and the middle lattice form a "long-long" defect.

5. A computer program, characterized in that, The computer program enables the computer to execute the method according to any one of claims 1 to 4.

6. An electronic device, characterized in that, It includes: A processor and a memory; The memory is used to store the computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device executes the method according to any one of claims 1 / 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it realizes the method according to any one of claims 1 to 4.

8. A chip, characterized in that, It includes: A processor, which is used to call and run the computer program from the memory, so that the device equipped with the chip executes the method according to any one of claims 1 to 4.

9. A computer program product, characterized in that, The computer program product includes a computer storage medium storing a computer program, the computer program including instructions executable by at least one processor, and when the instructions are executed by the at least one processor, implementing the method according to any one of claims 1 to 4.

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