A multi-parameter quantum sensing optical quantum chip and a preparation method and application thereof

Abstract

The application discloses a kind of multi-parameter quantum sensing optical quantum chip and preparation method and application thereof, it is related to quantum information technology, optoelectronic technology and nonlinear optics field.The optical quantum chip provided by the application includes substrate, and optical path is arranged on the substrate;The optical path includes the classical laser processing unit connected and arranged, nonlinear unit, sensing unit and quantum state output unit;Nonlinear unit includes the first entangled photon pair generation waveguide and the second entangled photon pair generation waveguide arranged in parallel;Sensing unit includes reference arm waveguide and sensing arm waveguide;Quantum state output unit includes the third beam splitter in communication with reference arm and sensing arm.The optical quantum chip provided by the application can significantly improve the sensitivity, accuracy, spatial resolution, expansibility, integration and stability of optical quantum sensing.The application also provides the preparation method and application of the above optical quantum sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the fields of quantum information technology, optoelectronics technology and nonlinear optics, and in particular to a multi-parameter quantum sensing optical quantum chip and a preparation method and application thereof. BACKGROUND

[0002] Due to the classical shot noise limit, when a physical quantity is measured N times, the final standard deviation will converge to Quantum sensing and precision measurement make use of quantum entanglement or particle coherence, and in a suitable measurement basis, the uncertainty can reach the Heisenberg limit (1 / N), which will exceed the accuracy of the classical statistical limit. In optical systems, both continuous variable and discrete variable quantum sensing and precision measurement show theoretical and experimental advantages. Integrated optics integrates discrete elements in bulk optical circuits onto a chip, which is very compact in size, enhances scalability, is programmable, and the entire system is more stable, which can accelerate the development of optical quantum sensing and precision measurement technology towards practicality. The main functional structures of the optical quantum chip include integrated quantum light sources, optical quantum information processing lines, and optical quantum state detection. Integrated quantum light sources are generally prepared by spontaneous nonlinear processes, such as spontaneous parametric down-conversion based on second-order nonlinearity and spontaneous four-wave mixing effect based on third-order nonlinearity to generate photon pair sources with time correlation and various types of entangled sources. Integrated optical quantum information processing lines are generally based on linear optical networks, such as optical waveguides, Mach-Zehnder interferometers, etc. Silicon has a large third-order nonlinear coefficient, and the processing of silicon chips is compatible with CMOS technology, in addition, the chip can be configured by thermal-optic effect, so silicon chips have the advantages of low cost and mass production, which are conducive to the development of large-scale and high-integration optical quantum chips. In addition, silicon nitride, aluminum gallium arsenide, silicon dioxide and lithium niobate are also used in optical quantum chips.

[0003] However, the current optical quantum sensing and precision measurement technology is mainly based on platform optics, which is not easy to stabilize, does not have good functional expansion ability and programmable ability, and is not conducive to the miniaturization of the system. Therefore, there is a lack of optical quantum chip configuration scheme for quantum sensing and precision measurement technology. SUMMARY

[0004] The present application aims to solve the above-mentioned problems, and provides a multi-parameter quantum sensing optical quantum chip, which can significantly improve the sensitivity, accuracy, spatial resolution, scalability, integration, stability, etc. of quantum sensing.

[0005] The present application also provides a preparation method of the above-mentioned optical quantum chip.

[0006] The present application also provides an application of the above-mentioned optical quantum chip.

[0007] According to the embodiment of the first aspect of the application, a multi-parameter quantum sensing optical quantum chip is provided, comprising a substrate, and an optical path arranged on the substrate;

[0008] The optical path comprises a classical laser processing unit, a nonlinear unit, a sensing unit and a quantum state output unit arranged in connection;

[0009] The classical laser processing unit comprises a first beam splitter arranged in connection, a first waveguide and a second waveguide arranged in parallel, and a second beam splitter; the first waveguide is provided with a first phase shifter; the second waveguide is provided with a second phase shifter;

[0010] The nonlinear unit comprises a first entangled photon pair generation waveguide and a second entangled photon pair generation waveguide arranged in parallel and connected with the second beam splitter;

[0011] The sensing unit comprises a reference arm in communication with the first entangled photon pair generation waveguide, and a sensing arm connected with the second entangled photon pair generation waveguide;

[0012] The quantum state output unit comprises a third beam splitter in communication with the reference arm and the sensing arm.

[0013] The operation mechanism of the optical quantum chip provided by the application is as follows:

[0014] The classical laser processing unit can be regarded as a Mach-Zehnder interferometer, comprising two fixed-ratio beam splitters and an adjustable phase shifter, which can realize beam splitting and phase modulation of pump light; specifically: after the pump laser passes through the first beam splitter, two beams of light are input into the first waveguide and the second waveguide; and the phase difference between the two pump lights is adjusted through the first phase shifter and the second phase shifter arranged thereon; then the two pump lights are converged and further split through the second beam splitter.

[0015] The entangled photon generation process occurs in the nonlinear unit, based on the third-order nonlinear spontaneous four-wave mixing effect or the second-order nonlinear parametric down-conversion process, and a photon pair is generated from the upper optical path or the lower optical path to form a path squeezed state

[0016] The processing of the entangled photons in the sensing unit converts the physical quantity to be measured into the phase information of the optical path on the sensing arm, and further regulates the optical quantum state; the quantum state output unit is used to realize quantum state interference to obtain various quantum state outputs, and then the measurement is performed through a suitable projection measurement basis. Specifically, the sensing unit regulates the phase difference φ of the squeezed state through the sensing parameter, and realizes the interference of the entangled photons on the third beam splitter; the two-photon path squeezed state For example, if the path bunching state generated by the nonlinear unit has the same phase in the upper and lower light paths after passing through the sensing area, the bunching state is separated into two states after HOM interference (third beam splitter), i.e. For a general path bunching state with a phase difference φ, the superposition of the separated state and the bunching state is obtained after interference, i.e.

[0017]

[0018] According to the control method of the embodiment of the present application, at least the following beneficial effects are achieved:

[0019] The optical quantum chip provided by the present application can realize temperature, solution concentration, humidity, gas concentration, electric field and other physical parameter detection through the combination and cooperation of each unit, and has the characteristics of high sensitivity, high precision, high integration, high spatial resolution, miniaturization, good stability, portability, configurability and the like. Specifically:

[0020] (1) On the optical quantum chip, due to the arrangement of the classical laser processing unit and the nonlinear unit and the limitation of the special form, the quantum light source is easy to realize, the 2-photon bunching state preparation based on path encoding is relatively simple, and the quantum state control can be realized through the phase shifter and other components in the classical laser unit.

[0021] (2) The optical quantum chip includes the sensing unit and the quantum state output unit, and the two-photon HOM interference can realize 2-fold phase-sensitive quantum sensing parameter measurement; not limited to 2 photons, 4 photons, 6 photons and more photons, the bunching quantum state can realize higher phase-sensitive measurement.

[0022] (3) The optical quantum chip can realize multi-parameter quantum sensing, and the sensing unit can be used to sense the changes of temperature, refractive index concentration, humidity, gas concentration and electric field and other physical parameters, and realize various sensing functions on the same optical quantum chip.

[0023] According to some embodiments of the present application, the optical quantum chip further comprises a cover layer and a buried layer. The buried layer is arranged on the surface of the substrate, the optical path is located above the buried layer, and the cover layer covers the optical path.

[0024] According to some embodiments of the present application, the material of the buried layer comprises silicon dioxide.

[0025] According to some embodiments of the present application, the maximum thickness of the buried layer is 2.5-3.5 μm; for example, it can be about 3 μm.

[0026] According to some embodiments of the present application, the material of the cover layer comprises silicon dioxide.

[0027] According to some embodiments of the present application, the maximum thickness of the covering layer is 2.5-3.5 μm; for example, it can be about 3 μm.

[0028] According to some embodiments of the present application, the optical quantum chip further comprises at least one input port, which is connected with the first beam splitter. In actual operation, the optical quantum chip can work normally as long as one input port works stably; in order to further improve the operation stability of the optical quantum chip, two input ports are provided thereon.

[0029] According to some embodiments of the present application, the optical quantum chip further comprises a fiber array. In use, the pump light enters the input port through the fiber array; and finally, the pump light is coupled out of the optical quantum chip through the first output port and the second output port.

[0030] According to some embodiments of the present application, the first beam splitter is a 2x2 beam splitter.

[0031] According to some embodiments of the present application, the second beam splitter is a 2x2 beam splitter.

[0032] According to some embodiments of the present application, the second beam splitter and the first entangled photon pair generation waveguide are connected through a third waveguide.

[0033] According to some embodiments of the present application, the second beam splitter and the second entangled photon pair generation waveguide are connected through a fourth waveguide.

[0034] It can be understood that the first entangled photon pair generation waveguide and the second entangled photon pair generation waveguide are both mosquito coil type waveguides.

[0035] According to some embodiments of the present application, the material of the nonlinear unit comprises at least one of a third-order nonlinear waveguide material or a second-order nonlinear waveguide material; and the specific material selection comprises at least one of silicon, silicon nitride, aluminum gallium arsenide, silicon dioxide and lithium niobate. Thus, the process of converting the two pump lights into degenerate entangled photon pairs can rely on the spontaneous four-wave mixing effect of the third-order nonlinear waveguide material or the spontaneous parametric down-conversion effect of the second-order nonlinear waveguide material.

[0036] According to some embodiments of the present application, a third phase shifter is arranged on the reference arm.

[0037] The third phase shifter is used to adjust the phase difference of the bunching state entangled photon pairs generated by the nonlinear unit and set the working point of the sensor.

[0038] The first phase shifter, the second phase shifter and the third phase shifter are configured to change the phase of the optical path by changing the refractive index in the waveguide, and the implementation manner is not limited to the thermo-optic effect and the electro-optic effect, and various technologies capable of regulating the phase of the optical path such as the optical Kerr effect and the like.

[0039] According to some embodiments of the present application, the lengths of the sensing arm and the reference arm are not equal. Thus, the phase difference caused by the temperature can be utilized to perform the temperature sensing test.

[0040] According to some embodiments of the present application, the lengths of the sensing arm and the reference arm are equal, but the covering layer of the local region of the sensing arm is etched.

[0041] Thus, the sensing test of the solution, the gas concentration or the humidity and the like can be performed by utilizing the difference in the refractive index of the different exposed material regions.

[0042] The key of the present application is to arrange the sensing unit in the optical path, and the sensing unit comprises the reference arm and the sensing arm. The phases of the two arms are respectively regulated by the third phase shifter and the physical quantity on the optical path of the sensing arm, so as to regulate the phase difference of the entangled photon pairs in the bunch state, and to realize the quantum sensing parameter measurement with multiple phase sensitivities. The regulation of the optical path phase of the physical quantity on the sensing arm is mainly that the physical quantity has an influence on the refractive index of the sensing arm (or the local region thereof).

[0043] According to some embodiments of the present application, the third beam splitter is a 50:50 beam splitter (which splits the incident light according to the ratio of 1:1). Quantum interference occurs thereon to obtain multiple quantum state outputs, and then a suitable projection measurement basis is selected to perform the measurement.

[0044] According to some embodiments of the present application, the beam splitter is equivalent to a waveguide interferometer. The generated entangled photon state can be regulated, and the waveguide interferometer comprises at least one of a HOM interferometer, a Mach-Zehnder interferometer, a Michelson interferometer or a Franson interferometer.

[0045] According to some embodiments of the present application, the quantum state output unit further comprises a fifth waveguide, a sixth waveguide, a bent waveguide and a straight waveguide.

[0046] According to some embodiments of the present application, the optical quantum chip further comprises at least two output ports; and the output ports are connected with the third beam splitter.

[0047] The third beam splitter obtains two beams of light, one of which is sequentially output from the optical quantum chip via the fifth waveguide, the bent waveguide and the output port; and the other of which is sequentially output from the optical quantum chip via the sixth waveguide, the straight waveguide and the output port.

[0048] The quantum state outputted via the output port can be subjected to a projection measurement.

[0049] According to some embodiments of the present application, the optical quantum chip can realize multiple phase-sensitive physical parameter sensing for 2-photon, 4-photon, 6-photon and more photon bunching states. Taking 2-photon bunching state as an example, the adjustment of the 2-photon path entangled state is completed through two-photon HOM interference, and 2 times phase-sensitive quantum sensing parameter measurement can be obtained, and the sensing accuracy can exceed the classical shot noise limit. The sensing sensitivity of n-photon bunching state with photon number greater than 2 can reach n times of the classical process.

[0050] According to an embodiment of the second aspect of the present application, a preparation method of the optical quantum chip is provided, and the preparation method comprises arranging the optical path on the substrate.

[0051] Since the preparation method adopts all the technical solutions of the optical quantum chip in the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0052] The preparation method is a standard micro-nano processing technology, including the steps of preparing a silicon substrate, photoetching a chip structure, etching a waveguide, preparing a silicon dioxide buried layer, and making a metal electrode. The photoetching chip structure and the etching waveguide are used to form the optical path. Further, the arrangement method of the optical path comprises at least one of a photoetching method, an electron beam exposure method, a chemical exchange method, a mechanical cutting method and a chemical mechanical polishing method. It should be noted that the order of the above steps can be adjusted during the processing of the optical quantum chip. Those skilled in the art can select appropriate parameters, methods and step orders according to operation experience and the specific structure of the optical quantum chip.

[0053] According to an embodiment of the third aspect of the present application, the optical quantum chip is applied in temperature, solution concentration, humidity, gas concentration and electric field tests.

[0054] Since the application adopts all the technical solutions of the optical quantum chip in the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments.

[0055] Unless otherwise specified, the meaning of "about" in the present application actually means that the allowable error is within ±2%, for example, about 100 actually means 100±2%*100.

[0056] Unless otherwise specified, "between" in the present application includes the numbers, for example, "between 2-3" includes the end values 2 and 3.

[0057] Other features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is a structural schematic diagram of the present application;

[0059] Figure 2 is a temperature sensing calculation given by embodiment 1 of the present application;

[0060] Figure 3 is a solution concentration sensing calculation given by embodiment 2 of the present application;

[0061] Figure 4 is an air humidity sensing calculation given by embodiment 3 of the present application;

[0062] Figure 5 is a cross-sectional schematic diagram of a waveguide in a light quantum chip in embodiments 1-3 of the present application.

[0063] Reference Signs:

[0064] Pump light 1;

[0065] Optical fiber array 2;

[0066] First input port 4, second input port 5;

[0067] First beam splitter 7, first waveguide 8, second waveguide 9, first phase shifter 10, second phase shifter 11, second beam splitter 12;

[0068] Third waveguide 13, fourth waveguide 14, first entangled photon pair generation waveguide 15, second entangled photon pair generation waveguide 16;

[0069] Reference arm 17, sensing arm 18, third phase shifter 19;

[0070] Third beam splitter 20, fifth waveguide 21, sixth waveguide 22;

[0071] First output port 3, second output port 6. DETAILED DESCRIPTION

[0072] The concept and the resulting technical effects of the present application will be described below in conjunction with embodiments so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0073] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the description, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0074] Embodiment 1

[0075] The present example provides a silicon-based material-based multi-parameter quantum sensing optical quantum chip, and performs temperature sensing calculation.

[0076] Reference Figure 1 The optical quantum chip provided by the present example comprises:

[0077] The multi-parameter quantum sensing optical quantum chip comprises a substrate and an optical path arranged on the substrate;

[0078] The optical path comprises an input port, a classical laser processing unit, a nonlinear unit, a sensing unit, a quantum state output unit and an output port;

[0079] The input port comprises an optical fiber array 2, a first input port 4 and a second input port 5 (one of which is a backup input port); the output port comprises a first output port 3 and a second output port 6;

[0080] The classical laser processing unit comprises a first beam splitter 7 connected to the first input port 4 and the second input port 5; and a first waveguide 8 and a second waveguide 9 connected to the first beam splitter 7 and arranged in parallel, the first waveguide 8 being provided with a first phase shifter 10, and the second waveguide 9 being provided with a second phase shifter 11; a second beam splitter 12 connected to the first waveguide 8 and the second waveguide 9;

[0081] The nonlinear unit comprises a third waveguide 13 and a fourth waveguide 14 connected to the second beam splitter 12; and a first entangled photon pair generation waveguide 15 connected to the third waveguide 13 and a second entangled photon pair generation waveguide 16 connected to the fourth waveguide 14; the length of the first entangled photon pair generation waveguide 15 (mosquito incense type waveguide) and the second entangled photon pair generation waveguide 16 (mosquito incense type waveguide) is 1 cm.

[0082] The sensing unit comprises a reference arm 17 connected with the first entangled photon pair generating waveguide 15 and a sensing arm 18 connected with the second entangled photon pair generating waveguide 16; the reference arm 17 is provided with a third phase shifter 19; the length difference AL of the two arms of the sensing unit is set to 87.964 μm. The length difference determines the accuracy and range of the obtained optical quantum chip for temperature sensing test.

[0083] The quantum state output unit comprises a third beam splitter 20 connected with the reference arm 17 and the sensing arm 18; a fifth waveguide 21 and a sixth waveguide 22 connected with the third beam splitter 20; the fifth waveguide 21 is connected with the first output port 3 via a bent waveguide; the sixth waveguide 22 is connected with the second output port 6 via a straight waveguide.

[0084] Reference Figure 5 The optical quantum chip provided in the example uses a silicon (Si) based waveguide, the cross-sectional width and height of the waveguide are 500 nm and 220 nm respectively, the cover layer and the buried layer are both 3 μm thick silicon dioxide, the substrate is a silicon substrate, and the body material of the waveguide is silicon. The waveguide mentioned here includes the first waveguide 8, the second waveguide 9, the third waveguide 13, the fourth waveguide 14, the first entangled photon pair generating waveguide 15, the second entangled photon pair generating waveguide 16, the reference arm 17, the sensing arm 18, the fifth waveguide 21 and the sixth waveguide 22.

[0085] In the optical quantum chip provided in the example, the size of any beam splitter is 140 μm x 40.5 μm; the length of the three phase shifters is all 180 μm.

[0086] The preparation method of the optical quantum chip provided in the example is a standard micro-nano processing technology, which includes the steps of preparing a silicon substrate, photoetching chip structure, etching waveguide, preparing a silicon dioxide buried layer, and making a metal electrode. In use, continuous pump light 1 with a wavelength of 1549.32 nm enters the optical quantum chip via the first input port 4; the working power of the first phase shifter 10 and the second phase shifter 11 is adjusted by a direct current power supply to change the phase difference of the first waveguide 8 or the second waveguide 9 (i.e. the two arms of the Mach-Zehnder interferometer), and the π phase consumption power is 25 mW; the pump light power is equally distributed in the third waveguide 13 and the fourth waveguide 14. The wavelengths of the entangled photon pairs output by the first entangled photon pair generating waveguide 15 and the second entangled photon pair generating waveguide 16 are 1546.02 nm and 1552.52 nm respectively; the full width at half maximum of the generated photon pairs is 54 nm.

[0087] The calculation process of temperature sensing is as follows:

[0088] In the sensing unit, the phase difference of the two arms With the change of the overall temperature T of the sensing unit satisfying Where λ is the wavelength. The effective refractive index *n* of the silicon waveguide (sensing arm and reference arm) changes per unit temperature, where ΔL is the difference in arm length between the two arms. In the silicon waveguide used in this example, RIU is approximately equal to 1.87 × 10⁻⁶. -4 ℃ -1 Therefore, when the temperature change reaches 94℃, the phase difference changes by 2π. (Single-photon state) After passing through the sensing unit and undergoing phase modulation (third phase shifter 19), it becomes... The output state after interference from a 50:50 beam splitter (third beam splitter 20) becomes Two-photon path focusing state (Generated from the nonlinear unit) After passing through the sensing unit and undergoing phase modulation (third phase shifter 19), it becomes... The output state after interference from a 50:50 beam splitter (third beam splitter 20) becomes

[0089] Therefore, this example utilizes the two-photon path-focused state (generated from a nonlinear unit) to achieve temperature sensing with twice the phase sensitivity. The |11> state is selected as the projection measurement basis to measure the two-photon coincidence counting interferometry curve. The theoretical calculated value is as follows: Figure 2 As shown.

[0090] Example 2

[0091] This example provides an optical quantum chip for multi-parameter quantum sensing based on silicon-based materials, and uses it to perform sodium chloride solution concentration sensing calculations; the specific difference from Example 1 is:

[0092] In this example of a photonic quantum chip, the reference arm 17 and the sensing arm 18 are of equal length. However, the silicon dioxide capping layer of the silicon waveguide on the sensing arm needs to be etched away, exposing it to air. The etching length L is 300 μm. Without damaging the structure, the longer L is, the higher the sensing accuracy.

[0093] The concentration sensing calculation process is as follows:

[0094] In the sensing unit, the phase difference between the two arms As the solution concentration m of the sensing unit changes, it satisfies Where λ is the wavelength. The change in refractive index n1 of a solution with respect to a unit change in concentration; taking sodium chloride solution as an example, RIUneff is approximately equal to 0.14585%. -1 . The effective refractive index *n* of the windowed waveguide (sensor arm) changes with the refractive index *n*1 of the solution. In this example, under the silicon waveguide (sensor arm) parameters, *RIUmf* is approximately equal to 1.8 × 10⁻⁶. -3Therefore, when the concentration of the sodium chloride solution changes by 20%, the phase difference changes by 2π. If it is a single-photon state After passing through the sensing unit, it becomes After passing through the 50:50 beam splitter (third beam splitter 20), the output state becomes The two-photon path bunching state in this example After passing through the sensing unit, it becomes After passing through the 50:50 beam splitter (third beam splitter 20), the output state becomes

[0095] Therefore, the two-photon path bunching state in this example can realize twice the phase sensitivity of the solution concentration sensing. The |11> state is selected as the projection measurement basis to measure the two-photon coincidence counting interference curve, and the theoretical calculation value is as shown in Figure 3

[0096] Embodiment 3

[0097] This example provides a light quantum chip for multi-parameter quantum sensing based on silicon-based materials, and uses it to perform air humidity sensing calculation. The difference between this example and embodiment 2 is that the sensing calculation process is different. The humidity sensing calculation process of this example is as follows:

[0098] The phase difference of the two arms With the change of the humidity h of the sensing unit satisfying Where λ is the wavelength. RIUhf represents the change in the effective refractive index n of the windowed part of the waveguide (sensing arm) under the change of unit humidity. Under the parameters of the silicon waveguide (sensing arm) used in this example, RIUhf is approximately equal to 1.46x10 -4 -1 Therefore, when the air humidity changes by 36%, the phase difference changes by 2π. If it is a single-photon state After passing through the sensing unit, it becomes After passing through the 50:50 beam splitter (third beam splitter 20), the output state becomes The two-photon path bunching state in this example After passing through the sensing unit, it becomes After passing through the 50:50 beam splitter (third beam splitter 20), the output state becomes

[0099] ​​Therefore, the air humidity sensor with double phase sensitivity can be realized by using the two-photon path bunch state (nonlinear unit) in this example. The state |11> is selected as the projection measurement base to measure the two-photon coincidence counting interference curve, and the theoretical calculation value is shown in Table 1. Figure 4

[0100] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.​

Claims

1. An optical quantum chip for multi-parameter quantum sensing, characterized in that, The multi-parameter quantum sensing optical quantum chip comprises a substrate and an optical path arranged on the substrate; The optical path comprises a classical laser processing unit, a nonlinear unit, a sensing unit and a quantum state output unit arranged in connection; The classical laser processing unit comprises a first beam splitter (7), a first waveguide (8) and a second waveguide (9) arranged in parallel, and a second beam splitter (12); the first waveguide (8) is provided with a first phase shifter (10); the second waveguide (9) is provided with a second phase shifter (11); The nonlinear unit comprises the second beam splitter (12) and comprises a first entangled photon pair generation waveguide (15) and a second entangled photon pair generation waveguide (16) arranged in parallel; The sensing unit comprises a reference arm (17) in communication with the first entangled photon pair generation waveguide (15), and a sensing arm (18) connected with the second entangled photon pair generation waveguide (16); The quantum state output unit comprises a third beam splitter (20) in communication with the reference arm (17) and the sensing arm (18).

2. The photonic quantum chip of claim 1, wherein, The optical quantum chip further comprises a cover layer and a buried layer; the buried layer is arranged on the surface of the substrate, the optical path is located above the buried layer, and the cover layer covers the optical path.

3. The optical quantum chip of claim 2, wherein, The lengths of the sensing arm (18) and the reference arm (17) are not equal; and / or, the lengths of the sensing arm (18) and the reference arm (17) are equal, and the cover layer of a local area of the sensing arm (18) is etched.

4. The photonic quantum chip of claim 1, wherein, The second beam splitter (12) and the first entangled photon pair generation waveguide (15) are connected through a third waveguide (13); and / or, the second beam splitter (12) and the second entangled photon pair generation waveguide (16) are connected through a fourth waveguide (14).

5. The photonic quantum chip of claim 1, wherein, The reference arm (17) is provided with a third phase shifter (19).

6. The photonic quantum chip according to any one of claims 1 to 5, characterized in that, The optical quantum chip comprises at least one input port, the input port is connected with the first beam splitter (7); and / or, the optical quantum chip further comprises at least two output ports; the output port is connected with the third beam splitter (20).

7. The photonic quantum chip according to any one of claims 1 to 5, characterized in that, The material of the nonlinear unit comprises at least one of silicon, silicon nitride, aluminum gallium arsenide, silicon dioxide and lithium niobate.

8. A method for producing a photonic quantum chip according to any one of claims 1 to 7, characterized in that, The preparation method comprises arranging the optical path on the substrate.

9. The preparation method according to claim 8, characterized in that, The arrangement method of the optical path comprises at least one of photolithography, electron beam exposure, chemical exchange, mechanical cutting and chemical mechanical polishing.

10. Application of the optical quantum chip according to any one of claims 1-7 in temperature, solution concentration, humidity, gas concentration and electric field tests.

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