Two-dimensional photon-integrated quantum walk chip and system

Abstract

Disclosed in the present invention are a two-dimensional photon-integrated quantum walk chip and system, which are applied to the technical field of quantum information. The chip comprise a two-dimensional photon-integrated quantum walk structure, wherein the two-dimensional photon-integrated quantum walk structure comprises a cladding, and at least two waveguide layers stacked in a thickness direction, each waveguide layer comprises at least two waveguides, and the cladding wraps the waveguides; the waveguides are parallel to each other, and the waveguides are distributed in a matrix mode in a plane perpendicular to the extension direction of the waveguides; and any waveguide is coupled to a waveguide in a row direction, a column direction and a diagonal direction. By providing multiple waveguide layers and providing at least two waveguides in each waveguide layer, a waveguide array distributed in a matrix mode can be formed, and any waveguide is coupled to a waveguide in a row direction, a column direction and a diagonal direction, such that after one waveguide receives photons, a two-dimensional optical quantum walk model in a plane can be implemented on the basis of a coupling relationship.

Description

A two-dimensional photon integrated quantum walking chip and system Technical Field

[0001] The present invention relates to the field of quantum information technology, and in particular to a two-dimensional photon integrated quantum walk chip and a two-dimensional photon integrated quantum walk system. Background Art

[0002] A classical random walk (or random walk) is a mathematical statistical model used to describe the trajectory generated by a random process in a mathematical space. It can be used to study the statistical properties of complex systems. In a one-dimensional random walk, the walker moves one unit left or right with a fixed probability per unit of time starting from position x on the number axis. In a multidimensional random walk, the walker can move one unit in any direction with a fixed probability per unit of time. Classical random walks have important applications in finance, physics, chemistry, biology, ecology, computer science, and other fields. For example, they are used to simulate stock price fluctuations, the paths of molecules propagating in liquids or gases, the search paths of foraging animals, and to estimate the value of π.

[0003] A quantum walk (also known as a quantum walk, quantum random walk, or quantum walk) is a quantum form of the classical random walk model, describing the motion of quantum particles in space. During a quantum walk, particles jump from one location to another with a probability determined by the particle's wave function. Quantum walks are a common tool in quantum computing and are widely used in the field of quantum information. They can solve problems that are intractable to classical computers, such as graph theory, search, and factorization. Compared to classical random walks, quantum walks can exponentially accelerate search and computational problems.

[0004] Quantum random walks are an extension of classical random walks in quantum mechanics. Unlike classical random walks, due to the superposition of quantum states, the characteristics of particles walking in a lattice must be explained using the statistical laws of quantum mechanical wave functions. Research suggests that demonstrating quantum random walks in quantum devices is an important path to achieving quantum computing.

[0005] Therefore, how to provide a two-dimensional photon integrated quantum walk chip structure that can realize the two-dimensional optical quantum walk model is an urgent problem that technicians in this field need to solve.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide a two-dimensional photon integrated quantum walk chip that can realize a two-dimensional light quantum walk model; another purpose of the present invention is to provide a two-dimensional photon integrated quantum walk system that can realize a two-dimensional light quantum walk model.

[0008] In order to solve the above technical problems, the present invention provides a two-dimensional photon integrated quantum walk chip, including a two-dimensional photon integrated quantum walk structure;

[0009] The two-dimensional photon integrated quantum walk structure includes a cladding layer and at least two waveguide layers stacked along the thickness direction, each waveguide layer includes at least two waveguides, and the cladding layer wraps the waveguides;

[0010] The waveguides are parallel to each other and are distributed in a matrix in a plane perpendicular to the extending direction of the waveguides; any waveguide is coupled with another waveguide in a row direction, a column direction, and a diagonal direction.

[0011] Optionally, the two-dimensional photonic integrated quantum walk structure includes at least three waveguide layers, and each waveguide layer includes at least three waveguides distributed at equal intervals.

[0012] Optionally, the waveguide coupled with the remaining eight waveguides among the plurality of waveguides is the input waveguide.

[0013] Optionally, it further includes a light source and an optical routing network, wherein the light source is connected to the input end of the optical routing network, and the output end of the optical routing network is connected to the input end of the corresponding waveguide.

[0014] Optionally, the optical routing network includes a vertical routing network and multiple layers of horizontal routing networks stacked along the thickness direction, and the output end of the horizontal routing network is connected to the input end of the waveguide in the corresponding waveguide layer;

[0015] An input end of the horizontal routing network is optically connected to an output end of the vertical routing network.

[0016] Optionally, the vertical routing network includes a multi-stage Mach-Zehnder interferometer unit corresponding one-to-one to the horizontal routing network, and a vertical coupler located between adjacent horizontal routing networks;

[0017] In the vertical routing network, the input end of the vertical coupler is coupled to an output end of a Mach-Zehnder interferometer unit, and the output end of the vertical coupler is coupled to the input end of the Mach-Zehnder interferometer unit in another adjacent layer.

[0018] Optionally, an input end of a Mach-Zehnder interferometer unit located at a lowermost layer or an uppermost layer in the vertical routing network is optically connected to an output end of the light source.

[0019] Optionally, the vertical coupler includes a first tapered waveguide located in one layer, and a second tapered waveguide located in another adjacent layer; the first tapered waveguide and the second tapered waveguide are stacked and coupled in reverse.

[0020] Optionally, the horizontal routing network is provided with multi-stage Mach-Zehnder interferometer units distributed in a tree structure to form multiple optical paths;

[0021] The input end of the horizontal routing network is optically connected to the output end of the corresponding Mach-Zehnder interferometer unit in the vertical routing network.

[0022] The present invention also provides a two-dimensional photon integrated quantum walk system, comprising a laser emitting device, a detector array, and a two-dimensional photon integrated quantum walk chip as described above, wherein the laser emitting device is used to emit laser to the two-dimensional photon integrated quantum walk chip, and the detector array is used to obtain the optical signal output by the two-dimensional photon integrated quantum walk chip.

[0023] The present invention provides a two-dimensional photon integrated quantum walk chip, comprising a two-dimensional photon integrated quantum walk structure; the two-dimensional photon integrated quantum walk structure comprises a cladding and at least two waveguide layers stacked along the thickness direction, each waveguide layer comprising at least two waveguides, and the cladding wraps the waveguides; the waveguides are parallel to each other and arranged in a matrix in a plane perpendicular to the waveguide extension direction; any waveguide is coupled to a waveguide in the row direction, the column direction, and the diagonal direction.

[0024] By providing multiple waveguide layers, with at least two waveguides in each waveguide layer, a waveguide array distributed in a matrix can be formed, and any of the waveguides is coupled with waveguides along the row, column, and diagonal directions. When a waveguide receives a photon, a two-dimensional light quantum walk model in a plane can be realized based on the above coupling relationship.

[0025] The present invention also provides a two-dimensional photon integrated quantum walk system, which also has the above-mentioned beneficial effects and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] FIG1 is a schematic front view of a two-dimensional photon integrated quantum walking structure in a two-dimensional photon integrated quantum walking chip provided by an embodiment of the present invention;

[0028] FIG2 is a side structural schematic diagram of FIG1 ;

[0029] FIG3 is a schematic structural diagram of a two-dimensional photon integrated quantum walking chip provided by an embodiment of the present invention;

[0030] FIG4 is a schematic diagram of the vertical routing network structure in FIG3;

[0031] FIG5 is a schematic diagram of the structure of the Mach-Zehnder interferometer unit in FIG4 ;

[0032] FIG6 is a schematic top view of the vertical coupler structure in FIG4 ;

[0033] FIG7 is a schematic diagram of the horizontal routing network structure in FIG3;

[0034] FIG8 is a schematic diagram of coupling in the yz cross section of the two-dimensional photon integrated quantum walk structure in this embodiment;

[0035] FIG9 is a schematic structural diagram of a two-dimensional photon integrated quantum walking system provided in this embodiment;

[0036] FIG10 is an xy cross-sectional light transmission diagram of the simulation results of the two-dimensional optical quantum walking chip of this embodiment;

[0037] FIG11 is a schematic diagram of xz cross-sectional light transmission of the simulation results of the two-dimensional optical quantum walk computing chip of this embodiment;

[0038] FIG12 shows the simulation results of the yz cross-sectional light field distribution of a single photon after propagating 500 μm in the optical quantum walking structure in the two-dimensional photon integrated quantum walking chip of this embodiment, as well as the probability distribution of projections in various directions;

[0039] FIG13 shows the simulation results of the yz cross-sectional light field distribution after a single photon propagates 1 mm in the light quantum walking structure in the two-dimensional light quantum walking chip of this embodiment, as well as the probability distribution of projections in various directions.

[0040] In the figure: 1. Waveguide, 2. Cladding, 3. Substrate, 4. Vertical routing network, 5. Horizontal routing network, 6. Mach-Zehnder interferometer unit, 61. 50:50 beam splitter, 62. Phase shifter, 63. First interferometer arm, 64. Second interferometer arm, 7. Vertical coupler, 71. First tapered waveguide, 72. Second tapered waveguide, 8. Laser emitting device, 9. Detector array. DETAILED DESCRIPTION

[0041] The core of the present invention is to provide a two-dimensional photon integrated quantum walk chip. In the prior art, one-dimensional micro-nano waveguides and air slot coupling arrays are used to realize a one-dimensional quantum walk model, but this can only realize a one-dimensional quantum walk model.

[0042] The present invention provides a two-dimensional photon integrated quantum walk chip, including a two-dimensional photon integrated quantum walk structure; the two-dimensional photon integrated quantum walk structure includes a cladding and at least two waveguide layers stacked along the thickness direction, each waveguide layer includes at least two waveguides, and the cladding wraps the waveguides; the waveguides are parallel to each other and are distributed in a matrix in a plane perpendicular to the waveguide extension direction; any waveguide is coupled with a waveguide along the row direction, column direction, and diagonal direction.

[0043] By providing multiple waveguide layers, with at least two waveguides in each waveguide layer, a waveguide array distributed in a matrix can be formed, and any of the waveguides is coupled with waveguides along the row, column, and diagonal directions. When a waveguide receives a photon, a two-dimensional light quantum walk model in a plane can be realized based on the above coupling relationship.

[0044] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] Please refer to Figures 1 and 2. Figure 1 is a front view structural diagram of a two-dimensional photon integrated quantum walk structure in a two-dimensional photon integrated quantum walk chip provided by an embodiment of the present invention; Figure 2 is a side view structural diagram of Figure 1.

[0046] Referring to Figures 1 and 2, in an embodiment of the present invention, a two-dimensional photon integrated quantum walk chip includes a two-dimensional photon integrated quantum walk structure; the two-dimensional photon integrated quantum walk structure includes a cladding 2 and at least two waveguide layers stacked along the thickness direction, each waveguide layer includes at least two waveguides 1, and the cladding 2 wraps the waveguide 1; the waveguides 1 are parallel to each other, and the waveguides 1 are distributed in a matrix in a plane perpendicular to the extension direction of the waveguides 1; any waveguide 1 is coupled with the waveguide 1 in the row direction, column direction, and diagonal direction.

[0047] The above-mentioned two-dimensional photon integrated quantum walk structure is mainly used to realize the two-dimensional optical quantum walk model, that is, the quantum walk phenomenon is mainly realized based on this two-dimensional photon integrated quantum walk structure. In this embodiment, the two-dimensional photon integrated quantum walk structure requires the provision of waveguides 1 distributed in an array. Specifically, at least two waveguide layers are stacked along the thickness direction. Each waveguide layer includes at least two waveguides 1. Whether the waveguides 1 are in the same layer or in different layers, they must be parallel to each other. Providing multiple waveguides 1 in one waveguide layer is equivalent to providing multiple waveguides 1 in the row direction, while stacking multiple waveguide layers is equivalent to providing multiple waveguides 1 in the column direction. In this embodiment, the waveguides 1 of two adjacent waveguide layers need to be aligned with each other so that the waveguides 1 can present a matrix distribution in a plane perpendicular to the extension direction of the waveguides 1. For example, when a total of two waveguide layers are provided, and each waveguide layer is provided with two waveguides 1, it can specifically form a 2×2 matrix distributed waveguide array. At this point, any waveguide 1 in the waveguide array is coupled to another waveguide 1 along the row, column, and diagonal directions. This means that in a matrix-distributed waveguide array, one waveguide 1 is coupled to at least three waveguides 1. Obviously, as the waveguide array expands, a waveguide 1 can be coupled to an even greater number of waveguides 1. During a quantum walk, photons can jump from one coupled waveguide 1 to another.

[0048] In this embodiment, the two-dimensional photon integrated quantum walk structure further includes a cladding 2, which wraps around each of the waveguides 1, allowing photons to propagate along any of the waveguides 1. The specific materials of the waveguides 1 and cladding 2 can be referenced in the prior art and will not be further described here. The cladding 2 and each of the waveguides 1 are typically disposed on the surface of a substrate 3. The specific material of the substrate 3 can be determined based on actual conditions and is not specifically limited here.

[0049] Specifically, in this embodiment, the two-dimensional photonic integrated quantum walk structure includes at least three waveguide layers, each of which includes at least three equally spaced waveguides 1. In each waveguide layer, the equally spaced waveguides 1 can form a regularly distributed waveguide array. In this embodiment, the cross-section of a single waveguide 1 perpendicular to the extension direction can be circular or rectangular, depending on the specific situation. Taking a rectangular waveguide 1 as an example, the thickness of the waveguide 1 can be h, the width of the waveguide 1 can be w, the spacing between adjacent waveguides 1 in the same layer can be g, and the spacing between adjacent waveguides 1 in the same column can be d.

[0050] Combined with the above description, in this embodiment, a waveguide array of at least 3×3 can be formed. In this case, the waveguide 1 located in the center can be coupled with a total of eight waveguides 1 along the row, column, and diagonal directions; the waveguide 1 located in the corner can be coupled with a total of three waveguides 1 along the row, column, and diagonal directions; and the waveguide 1 located at the edge can be coupled with a total of five waveguides 1 along the row, column, and diagonal directions. As the above waveguide array expands, the number of waveguides 1 located at the edge coupled with five waveguides 1 and the number of waveguides 1 located in the center coupled with eight waveguides 1 can be further increased.

[0051] In this embodiment, the waveguide 1 coupled to the remaining eight waveguides 1 among the plurality of waveguides 1 can be set as the input waveguide 1. That is, the waveguide 1 at the center of the waveguide array is selected as the input waveguide 1. The so-called input waveguide 1 is the waveguide 1 for inputting photons. Because this input waveguide 1 is coupled with the remaining eight waveguides 1, the quantum walk effect can be fully demonstrated in a two-dimensional plane, that is, along a plane perpendicular to the extension direction of the waveguide 1, fully realizing the two-dimensional light quantum walk model. Of course, in this embodiment, other waveguides 1 can also be selected as the input waveguide 1, depending on the actual situation and is not specifically limited here.

[0052] A two-dimensional photon integrated quantum walk chip provided in an embodiment of the present invention forms a waveguide array distributed in a matrix by providing multiple waveguide layers, with at least two waveguides 1 provided in each waveguide layer. Furthermore, any of the waveguides 1 is coupled with a waveguide 1 along the row, column, and diagonal directions. When a waveguide 1 receives a photon, a two-dimensional optical quantum walk model within a plane can be realized based on the coupling relationship.

[0053] The specific structure of the two-dimensional photon integrated quantum walk chip provided by the present invention will be described in detail in the following invention embodiments.

[0054] Please refer to Figure 3, which is a structural schematic diagram of a two-dimensional photon integrated quantum walk chip provided in an embodiment of the present invention; Figure 4 is a schematic diagram of the vertical routing network structure in Figure 3; Figure 5 is a schematic diagram of the Mach-Zehnder interferometer unit structure in Figure 4; Figure 6 is a top-down structural schematic diagram of the vertical coupler structure in Figure 4; Figure 7 is a schematic diagram of the horizontal routing network structure in Figure 3; Figure 8 is a coupling schematic diagram of the yz cross-section of the two-dimensional photon integrated quantum walk structure in this embodiment.

[0055] Different from the aforementioned invention embodiment, the present invention embodiment further defines the structure of the two-dimensional photon integrated quantum walk chip based on the aforementioned invention embodiment. The remaining content has been described in detail in the aforementioned invention embodiment and will not be repeated here.

[0056] Referring to Figure 3, in an embodiment of the present invention, the two-dimensional photonic integrated quantum walk chip further includes a light source and an optical routing network, the light source is connected to the input end of the optical routing network, and the output end of the optical routing network is connected to the input end of the corresponding waveguide 1.

[0057] The above-mentioned light source, optical routing network and two-dimensional photon integrated quantum walk structure can be specifically integrated into the same two-dimensional photon integrated quantum walk chip, so that they can share the same substrate 3. The above-mentioned light source is usually a single-photon source, which can specifically emit single photons to the two-dimensional photon integrated quantum walk structure. The single photon is usually pulsed light to simulate a single-photon quantum walk. Of course, the above-mentioned light source can be a continuous light source to achieve statistics of quantum walks, etc. The structure of the above-mentioned light source is not specifically limited in the embodiments of the present invention and depends on the specific circumstances. When a single-photon source is used, the single-photon source is composed of a single-photon generator and a filter. The single-photon source can specifically be composed of a single-photon generator realized by a microring resonator or a spiral optical waveguide, and a cascade of filters realized by a microring resonator or an unequal-arm Mach-Zehnder interferometer.

[0058] The above-mentioned optical routing network is a transmission structure between the light source and the two-dimensional photon integrated quantum walk structure. It is mainly used to transmit the photons output by the light source to the corresponding waveguide 1. Therefore, the light source needs to be connected to the input end of the optical routing network. The optical routing network usually has multiple output ends, and the output end of the optical routing network needs to be connected to the input end of the corresponding waveguide 1. Under normal circumstances, the output end of the optical routing network needs to be connected one-to-one with the waveguide 1 in the above-mentioned two-dimensional photon integrated quantum walk structure. Of course, the output end of the above-mentioned optical routing network can also be connected to only some of the waveguides 1 in the two-dimensional photon integrated quantum walk structure, such as the waveguide 1 located in the center, to transmit the photons to the corresponding waveguide 1 to realize quantum walk.

[0059] Specifically, the optical routing network includes a vertical routing network 4 and multiple layers of horizontal routing networks 5 stacked along the thickness direction, the output end of the horizontal routing network 5 is connected to the input end of the waveguide 1 in the corresponding waveguide layer; the input end of the horizontal routing network 5 is optically connected to the output end of the vertical routing network 4.

[0060] Since the two-dimensional photon integrated quantum walk structure in this embodiment is a multi-layer structure, the corresponding optical routing network also needs to realize the movement of photons in the row direction and along the column direction, so that the photons can be transmitted to the corresponding waveguide 1. Therefore, the optical routing network needs to include a vertical routing network 4 and a multi-layer horizontal routing network 5 stacked along the thickness direction. The vertical routing network 4 is used to move photons along the column direction, and the horizontal routing network 5 is used to move photons along the row direction. In this embodiment, the horizontal routing network 5 is stacked along the thickness direction, and the input end of the horizontal routing network 5 needs to be optically connected to the output end of the vertical routing network 4, and the output end of the horizontal routing network 5 needs to be connected to the input end of the corresponding waveguide 1. That is, in this embodiment, the photon will first be input into the vertical routing network 4, and the photon will be first transmitted to the layer where the input waveguide 1 is located through the vertical routing network 4, and then the photon will be transmitted to the input waveguide 1 through the horizontal routing network 5 of this layer.

[0061] Referring to FIG4 , in order to achieve the above functions, in this embodiment, the vertical routing network 4 includes a multi-stage Mach-Zehnder interferometer unit 6 corresponding one-to-one to the horizontal routing network 5, and a vertical coupler 7 located between adjacent horizontal routing networks 5; in the vertical routing network 4, the input end of the vertical coupler 7 is coupled to an output end of the Mach-Zehnder interferometer unit 6, and the output end of the vertical coupler 7 is coupled to the input end of the Mach-Zehnder interferometer unit 6 in another adjacent layer.

[0062] Referring to FIG5 , the Mach-Zehnder interferometer (MZI) unit 6 typically has two output ports, which can transmit input photons in a directionally directed manner to a certain output port, thereby controlling the photon transmission path. The Mach-Zehnder interferometer unit 6 can specifically be composed of an input optical waveguide, a 50:50 beam splitter 61, a first interferometer arm 63, a second interferometer arm 64, a phase shifter 62, and an output optical waveguide. The 50:50 beam splitter 61 can be a multimode interferometer, a directional coupler, or a Y-waveguide structure; the phase shifter 62 can be a thermo-optical phase shifter 62, an electro-optical phase shifter 62, a phase change material phase shifter 62, or the like. The phase shifter 62 can be provided on both the first interferometer arm 63 and the second interferometer arm 64, or on only one interferometer arm, without any specific limitation herein.

[0063] Referring to Figure 6 , in this embodiment, the vertical coupler 7 includes a first tapered waveguide 71 located in one layer and a second tapered waveguide 72 located in an adjacent layer; the first tapered waveguide 71 and the second tapered waveguide 72 are stacked in opposite directions. The vertical coupler 7 is formed by two tapered waveguides stacked and coupled along the thickness direction. A tapered waveguide is one with a greater width at one end than at the other. In this embodiment, the first tapered waveguide 71 and the second tapered waveguide 72 are parallel to each other but stacked in opposite directions. Specifically, the smaller end of the first tapered waveguide 71 is positioned opposite the wider end of the second tapered waveguide 72, and the wider end of the first tapered waveguide 71 is positioned opposite the smaller end of the second tapered waveguide 72. This vertical coupler 7 structure enables photons to be transmitted between different layers in the vertical routing network 4.

[0064] In the vertical routing network 4, the input end of the vertical coupler 7 is coupled to an output end of a Mach-Zehnder interferometer unit 6, and the output end of the vertical coupler 7 is coupled to the input end of the Mach-Zehnder interferometer unit 6 in another adjacent layer. At this time, the other output end of the Mach-Zehnder interferometer unit 6 needs to be connected to the input end of the corresponding horizontal routing network 5. The Mach-Zehnder interferometer unit 6 can determine whether the input photon needs to be transmitted to the adjacent layer through the vertical coupler 7. After the photon is transmitted to the target layer, it can be transmitted to the horizontal routing network 5 through the Mach-Zehnder interferometer unit 6, and then transmitted to the corresponding waveguide 1 through the corresponding horizontal routing network 5.

[0065] Preferably, in this embodiment, the input end of the Mach-Zehnder interferometer unit 6 located at the bottom or top layer of the vertical routing network 4 is optically connected to the output end of the light source. In this case, only one vertical coupler 7 is required between two adjacent layers of the horizontal routing network 5 to enable photons to propagate from bottom to top or from top to bottom in the vertical routing network 4.

[0066] Referring to FIG. 7 , in this embodiment, the horizontal routing network 5 is provided with a multi-stage Mach-Zehnder interferometer unit 6 arranged in a tree-like structure, forming multiple optical paths. The input end of the horizontal routing network 5 is optically connected to the output end of the corresponding Mach-Zehnder interferometer unit 6 in the vertical routing network 4. That is, in this embodiment, the horizontal routing network 5 is also formed using Mach-Zehnder interferometer units 6. Specifically, the Mach-Zehnder interferometer units 6 are arranged in a tree-like structure to form a multi-stage structure, thereby directionally transmitting photons received from the Mach-Zehnder interferometer units 6 in the vertical routing network 4 to the final target waveguide 1.

[0067] Referring to the horizontal routing network 5 provided in FIG7 , it can transmit single photons from the vertical routing network 4 to the input port of the two-dimensional photonic integrated quantum walk structure of the corresponding waveguide layer. The horizontal routing optical network shown in FIG7 is 1×11 and can route to up to 11 input ports. The number of output ports of the horizontal routing optical network N ≥ 2. In this embodiment, each waveguide layer is connected to a corresponding horizontal routing network 5. The horizontal routing network 5 inputs single photons to the designated input port of the optical quantum walk computing structure of the waveguide layer.

[0068] Figure 8 is a schematic diagram of coupling in the yz cross-section of a two-dimensional photonic integrated quantum walk structure according to this embodiment. The two-dimensional photonic integrated quantum walk structure shown in Figure 8 has five waveguide layers, with 11 waveguides 1 in each layer. The width of a waveguide 1 is w, and the gap between waveguides 1 is g. Referring to Figure 8 , the central waveguide 1 is used as an example for illustration. This waveguide 1 can couple with eight adjacent optical waveguides 1.

[0069] A two-dimensional photon integrated quantum walk chip provided in an embodiment of the present invention can transmit photons generated by a light source to a corresponding waveguide 1 through an optical routing network, thereby realizing two-dimensional optical quantum walk simulation.

[0070] Refer to FIG9 , which is a schematic structural diagram of a two-dimensional photon integrated quantum walking system provided in this embodiment.

[0071] The present invention also provides a two-dimensional photon integrated quantum walk system, comprising a laser emitting device 8, a detector array 9, and a two-dimensional photon integrated quantum walk chip provided in any of the above-mentioned embodiments of the invention, wherein the laser emitting device 8 is used to emit laser light to the two-dimensional photon integrated quantum walk chip, and the detector array 9 is used to obtain the optical signal output by the two-dimensional photon integrated quantum walk chip.

[0072] The laser emitting device 8 typically includes a laser, an optical amplifier, and a polarization controller arranged along the optical path. Laser light passing through the polarization controller is input into the light source, generating the desired photons. These photons are then transmitted through the optical routing network to the corresponding waveguide 1 in the 2D photon integrated quantum walk structure, thereby implementing a 2D optical quantum walk. The detector array 9 detects the signals generated by the quantum walk to obtain the quantum walk calculation results.

[0073] The specific steps of the quantum walking experiment process in this embodiment based on the above-mentioned two-dimensional photon integrated quantum walking chip are as follows:

[0074] The first step is to amplify the 1550nm wavelength laser through an optical amplifier, and then couple it into the two-dimensional photonic integrated chip after passing through a polarization controller.

[0075] Step 2: The input light passes through the on-chip integrated single-photon source structure to generate a single-photon source, which is then injected into a waveguide 1 of the two-dimensional photon integrated quantum walk chip.

[0076] Step 3: The output light of the output waveguide 1 of the two-dimensional photon integrated quantum walk chip is coupled out and detected by the superconducting nanowire single photon detector array 9 serving as the detector array 9.

[0077] Step 4: By analyzing the output light intensity of waveguide 1 at different positions, the probability distribution of discrete quantum walks at different positions is analyzed to obtain the calculation results of discrete quantum walks.

[0078] Figure 10 is a schematic diagram of the xy-section light transmission of the simulation results of the two-dimensional optical quantum walk chip of this embodiment. Figure 11 is a schematic diagram of the xz-section light transmission of the simulation results of the two-dimensional optical quantum walk computing chip of this embodiment. In the simulation results, the silicon nitride multilayer waveguide layer of the two-dimensional photonic integrated quantum walk structure has five layers, each including 11 parallel waveguides 1. All waveguides 1 have a width w of 1 μm, a thickness h of 450 nm, a gap g between horizontal waveguides of 222 nm, and a gap d between vertical waveguides of 500 nm, resulting in a light propagation length of 1 mm.

[0079] Figure 12 shows the simulated light field distribution in the yz cross section of the two-dimensional photon integrated quantum walk chip of this embodiment after a single photon propagates 500 μm in the optical quantum walk structure, as well as the probability distribution of projections in various directions. Figure 13 shows the simulated light field distribution in the yz cross section of the two-dimensional photon integrated quantum walk chip of this embodiment after a single photon propagates 1 mm in the optical quantum walk structure, as well as the probability distribution of projections in various directions. The two-dimensional optical quantum walk chip shown in this embodiment can be used to simulate a continuous quantum walk model or to implement a discrete quantum walk model by collecting the light field output intensities of different waveguides 1 and performing discretization processing.

[0080] The two-dimensional photon integrated quantum walk chip structure proposed in the embodiment of the present invention has the advantages of high integration, compatibility with CMOS (Complementary Metal Oxide Semiconductor) process, and low cost.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0082] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0083] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0084] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0085] The above is a detailed introduction to a two-dimensional photon integrated quantum walk chip and a two-dimensional photon integrated quantum walk system provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A two-dimensional photon integrated quantum walk chip, characterized in that: Including two-dimensional photon integrated quantum walk structure; The two-dimensional photon integrated quantum walk structure comprises a cladding, at least two waveguide layers stacked along a thickness direction, each of the waveguide layers comprises at least two waveguides, and the cladding wraps the waveguides; The waveguides are parallel to each other and are distributed in a matrix in a plane perpendicular to the extending direction of the waveguides; any waveguide is coupled with another waveguide in a row direction, a column direction, and a diagonal direction.

2. The two-dimensional photon integrated quantum walk chip according to claim 1, characterized in that: The two-dimensional photon integrated quantum walk structure includes at least three waveguide layers, and each waveguide layer includes at least three waveguides distributed at equal intervals.

3. The two-dimensional photon integrated quantum walk chip according to claim 2, characterized in that: The waveguide coupled with the remaining eight waveguides among the plurality of waveguides is an input waveguide.

4. The two-dimensional photon integrated quantum walk chip according to claim 1, characterized in that: It also includes a light source and an optical routing network, wherein the light source is connected to the input end of the optical routing network, and the output end of the optical routing network is connected to the input end of the corresponding waveguide.

5. The two-dimensional photon integrated quantum walk chip according to claim 4, characterized in that: The optical routing network includes a vertical routing network and multiple layers of horizontal routing networks stacked along the thickness direction, wherein the output end of the horizontal routing network is connected to the input end of the waveguide in the corresponding waveguide layer; An input end of the horizontal routing network is optically connected to an output end of the vertical routing network.

6. The two-dimensional photon integrated quantum walk chip according to claim 5, characterized in that: The vertical routing network includes a multi-stage Mach-Zehnder interferometer unit corresponding one-to-one to the horizontal routing network, and a vertical coupler located between adjacent horizontal routing networks; In the vertical routing network, the input end of the vertical coupler is coupled to an output end of a Mach-Zehnder interferometer unit, and the output end of the vertical coupler is coupled to the input end of the Mach-Zehnder interferometer unit in another adjacent layer.

7. The two-dimensional photon integrated quantum walk chip according to claim 6, characterized in that: The input end of the Mach-Zehnder interferometer unit located at the bottom layer or the top layer in the vertical routing network is optically connected to the output end of the light source.

8. The two-dimensional photon integrated quantum walk chip according to claim 6, characterized in that: The vertical coupler includes a first tapered waveguide located in one layer and a second tapered waveguide located in another adjacent layer; the first tapered waveguide and the second tapered waveguide are stacked and coupled in reverse.

9. The two-dimensional photon integrated quantum walk chip according to claim 5, characterized in that: The horizontal routing network is provided with multi-stage Mach-Zehnder interferometer units distributed in a tree structure to form multiple optical paths; The input end of the horizontal routing network is optically connected to the output end of the corresponding Mach-Zehnder interferometer unit in the vertical routing network.

10. A two-dimensional photon integrated quantum walk system, characterized in that: It comprises a laser emitting device, a detector array, and a two-dimensional photon integrated quantum walk chip as claimed in any one of claims 1 to 9, wherein the laser emitting device is used to emit laser to the two-dimensional photon integrated quantum walk chip, and the detector array is used to obtain the optical signal output by the two-dimensional photon integrated quantum walk chip.

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