Quantum random number generator based on co-fired ceramic integration

Abstract

The present invention provides a quantum random number generator based on co-fired ceramic integration, comprising: a co-fired ceramic substrate, and a quantum state preparation unit, a quantum state measurement chip, a first processing unit and a second processing unit which are integrated together on the co-fired ceramic substrate and connected in sequence, wherein the quantum state preparation unit comprises a laser chip, the quantum state measurement chip comprises an end face coupler, a light outlet of the laser chip and an input end of the end face coupler are three-dimensionally aligned using a preset alignment structure, and the preset alignment structure is formed on the co-fired ceramic substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum random number generation, and more specifically, to a quantum random number generator based on co-fired ceramic integration. Background Art

[0002] Random numbers are a widely used basic resource, and have extensive and important applications in many fields such as cryptography, numerical computing, neural network computing, traditional information security and quantum communication. The quantum random number generator is based on the basic principles of quantum physics. The quantum random numbers it generates are unpredictable and non-repeatable. Compared with traditional pseudo-random number generators and noise source random number generators, its source of randomness is clearer, and its randomness can be strictly proved by the minimum entropy theory. Therefore, it has higher security and is particularly suitable for application scenarios with high requirements for randomness. From a practical point of view, the quantum random number generator needs to have the characteristics of small size, high random number generation rate and strong stability.

[0003] In the process of realizing the concept of the present invention, the inventors found that a quantum random number generator can be realized based on an optical chip solution based on vacuum state fluctuation measurement. However, the optical chip solution based on vacuum state fluctuation measurement requires continuous laser as input. Although silicon-based optical chips can realize monolithic integration of passive devices, silicon is an indirect bandgap semiconductor with low direct luminescence efficiency. Therefore, it is impossible to directly integrate the light source on the silicon wafer. If the traditional grating coupling or lens coupling method is used to realize laser input, it faces the problems of low coupling efficiency and difficulty in controlling the overall volume. At the same time, the quantum random number generator needs to use microelectronic circuits to extract randomness and post-process the original data. Therefore, how to realize the optoelectronic integration of the light source, passive optical chip and back-end microelectronic circuit, there is currently a lack of more effective solutions. Summary of the invention

[0004] In view of this, the present invention provides a quantum random number generator based on co-fired ceramic integration.

[0005] One aspect of the present invention provides a quantum random number generator based on co-fired ceramic integration, comprising: a co-fired ceramic substrate, and a quantum state preparation unit, a quantum state measurement chip, a first processing unit, and a second processing unit that are integrated together on the co-fired ceramic substrate and connected in sequence, wherein the quantum state preparation unit includes a laser chip, the quantum state measurement chip includes an end face coupler, and the light output port of the laser chip and the input end of the end face coupler are three-dimensionally aligned using a preset alignment structure, and the preset alignment structure is formed on the co-fired ceramic substrate.

[0006] The quantum random number generator based on co-fired ceramic integration provided by the embodiment of the present invention realizes the photoelectric integration of the light source, the passive optical chip and the back-end microelectronic circuit by integrating the quantum state preparation unit, the quantum state measurement chip, the first processing unit and the second processing unit on a co-fired ceramic substrate, thereby improving the stability and output bandwidth of the system, and can effectively reduce the volume of the entire quantum random number generator system while reducing costs. In addition, through the alignment structure pre-designed on the co-fired ceramic substrate, the light outlet of the laser chip and the input end of the end coupler can be three-dimensionally aligned to minimize the input loss, thereby ensuring a high optical coupling efficiency between the laser chip and the end coupler. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0008] Figure 1 A schematic structural diagram of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown;

[0009] Figure 2 A top view of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown;

[0010] Figure 3 A perspective view of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown;

[0011] Figure 4 A quantum state preparation unit and a quantum state measurement chip according to an embodiment of the present invention are shown;

[0012] Figure 5 A schematic diagram showing the principle of a quantum random number generator according to an embodiment of the present invention is shown.

[0013] Explanation of the reference numerals: 100, quantum random number generator; 1, co-fired ceramic substrate; D1, alignment structure; d1, preset groove; 2, quantum state preparation unit; 21, laser chip; 22, vacuum state input; 3, quantum state measurement chip; 31, end coupler; 32, passive device; 4, first processing unit; 41, first photodetector chip; 42, transimpedance amplifier; 43, second photodetector chip; 5, second processing unit; 51, operational amplifier; 52, analog-to-digital converter; 53, randomness extraction circuit; 54, microcontroller unit; 55, memory unit. DETAILED DESCRIPTION

[0014] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0015] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0016] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0017] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0018] In the embodiments of the present invention, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage and other aspects of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0019] In the embodiment of the present invention, before obtaining or collecting the user's personal information, the user's authorization or consent is obtained.

[0020] Random numbers are a widely used basic resource, and have extensive and important applications in many fields such as cryptography, numerical computing, neural network computing, traditional information security, and quantum communication. Quantum random number generators are based on the basic principles of quantum physics. The quantum random numbers they generate are unpredictable and non-repeatable. Compared with traditional pseudo-random number generators and noise source random number generators, their randomness sources are clearer, and their randomness can be strictly proved by the minimum entropy theory. Therefore, they have higher security and are particularly suitable for application scenarios with high requirements for randomness.

[0021] Today, quantum random number generators have been implemented in a variety of ways, such as photon path selection, photon arrival time, laser phase fluctuation, and vacuum state fluctuation measurement. From a practical point of view, quantum random number generators need to be small in size, have a high random number generation rate, and have strong stability. The optical chip solution based on vacuum state fluctuation measurement does not require an optical interferometer, and the optical structure is simple, so it can be integrated on a single silicon chip. Quantum state measurement can be directly implemented on the chip, and the final random number generation rate can reach more than 10Gbps, which meets the standards of small size, high stability, and high speed for the next generation of quantum communication systems, and therefore has the best application prospects.

[0022] The above-mentioned optical chip solution based on vacuum state fluctuation measurement requires continuous laser as input. Although silicon-based optical chips can realize monolithic integration of passive devices, silicon is an indirect bandgap semiconductor with low direct luminescence efficiency, so it is impossible to directly integrate the light source on the silicon wafer. If the traditional grating coupling or lens coupling method is used to realize laser input, it faces the problems of low coupling efficiency and difficult to control the overall volume. At the same time, the quantum random number generator needs to use microelectronic circuits to extract randomness and post-process the original data. Therefore, how to realize the optoelectronic integration of the light source, passive optical chip and back-end microelectronic circuit is currently lacking a more effective solution.

[0023] In order to at least partially solve the technical problems existing in the related art, the present invention provides a quantum random number generator based on co-fired ceramic integration. The quantum random number generator based on co-fired ceramic integration includes: a co-fired ceramic substrate, and a quantum state preparation unit, a quantum state measurement chip, a first processing unit, and a second processing unit that are integrated on the co-fired ceramic substrate and connected in sequence, wherein the quantum state preparation unit includes a laser chip, the quantum state measurement chip includes an end face coupler, and the light outlet of the laser chip and the input end of the end face coupler are three-dimensionally aligned using a preset alignment structure, and the preset alignment structure is formed on the co-fired ceramic substrate.

[0024] Figure 1 A schematic structural diagram of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown.

[0025] Figure 2 A top view of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown.

[0026] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the quantum random number generator 100 includes: a co-fired ceramic substrate 1, and a quantum state preparation unit 2, a quantum state measurement chip 3, a first processing unit 4, and a second processing unit 5 which are integrated on the co-fired ceramic substrate 1 and connected in sequence. The quantum state preparation unit 2 includes a laser chip 21, and the quantum state measurement chip 3 includes an end coupler 31. The light outlet of the laser chip 21 and the input end of the end coupler 31 are three-dimensionally aligned using a preset alignment structure D1, and the preset alignment structure D1 is formed on the co-fired ceramic substrate 1.

[0027] According to an embodiment of the present invention, the co-fired ceramic substrate can be made of many single-piece ceramic substrates through lamination, hot pressing, debonding, sintering and other processes. Based on the multi-layer structure of the co-fired ceramic substrate, its wiring density is high, the length of the interconnection line can be shortened as much as possible, and the assembly density and signal transmission speed are improved. Therefore, the co-fired ceramic substrate can meet the requirements of the quantum random number generator for system miniaturization, high density, multi-function, high reliability, high speed, high power, etc.

[0028] According to an embodiment of the present invention, a quantum random number generator can generate true random numbers based on the principles of quantum physics, and has the characteristics of unpredictability, non-repeatability and unbiasedness, and is a key core component in a quantum communication system.

[0029] According to one embodiment of the present invention, the structure of the quantum random number generator may include three parts: entropy source, measurement, and post-processing. The entropy source outputs the quantum state, which is the source of quantum randomness. Measurement is the measurement of the entropy source, which generates initial random numbers. The initial data is affected by factors such as environmental noise, non-ideal entropy source, and measurement noise, and thus has certain bias and correlation. First, the entropy of the original data needs to be estimated, and then the randomness is extracted through the post-processing algorithm to finally obtain a complete quantum random number.

[0030] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the quantum state preparation unit 2 can be used to output the quantum state, and the quantum state measurement chip 3 can be used to measure the random signal generated by the quantum fluctuation. The first processing unit 4 and the second processing unit 5 can be used to process the data to obtain the quantum random number generated in real time. The co-fired ceramic substrate 1 can be used as a substrate to carry the aforementioned quantum state preparation unit 2, the quantum state measurement chip 3, the first processing unit 4 and the second processing unit 5, and provide electronic connections for each unit.

[0031] According to the embodiment of the present invention, the co-fired ceramic substrate 1 can provide physical support and electronic connection for the quantum state preparation unit 2, the quantum state measurement chip 3, the first processing unit 4 and the second processing unit 5, realize the optoelectronic integration of the light source, the passive optical chip and the back-end microelectronic circuit, improve the stability and output bandwidth of the system, and effectively reduce the volume of the entire system of the quantum random number generator 100 while reducing costs. As just one example, compared with the solution using lens optical coupling with a heat sink substrate, the overall volume of the quantum random number generator 100 provided by the embodiment of the present invention is reduced by 50%.

[0032] According to an embodiment of the present invention, quantum random number generators can be divided into discrete type and continuous type according to different random sources.

[0033] According to one embodiment of the present invention, a continuous quantum random number generator uses continuous laser pulses as an entropy source. Multiple random bits can be obtained in one measurement, and it is not limited by single-photon detectors, so the quantum random number generation rate is higher. Among them, a representative one is a quantum random number generator based on vacuum shot noise. The essence of vacuum shot noise is the statistical fluctuation of observation data caused by vacuum fluctuations. The measured value of the regular component X or P of the vacuum state is expressed as a Gaussian random variable. Usually, a homodyne detection device can be used to measure the regular component of the vacuum state. For example, it can be realized based on an optical chip solution for vacuum state fluctuation measurement. The advantages of this solution are that the vacuum state is easy to prepare, the system is simple and easy to integrate, and the shot noise is theoretically white noise with infinite bandwidth, so a large number of original random numbers can be obtained by sampling at one time.

[0034] According to an embodiment of the present invention, a coherent state is a pure state in quantum mechanics, which is closest to the quantum state of a classical light field. The photon number distribution in the coherent state obeys the Poisson distribution, and the quantum noise of its two orthogonal components is equal, which conforms to the minimum uncertainty relationship. In practical applications, coherent states are often used to describe the light field output by a laser. The vacuum state is a special case of n=0 in the photon number state, indicating a quantum state without any photons. Although there are no photons in the vacuum state, there are still quantum fluctuations in the electromagnetic field, which are called vacuum fluctuations. The vacuum state is the lowest limit of quantum noise, also known as the quantum noise limit. In a quantum random number generator, the fluctuations in the vacuum state can be used as a source for generating true random numbers.

[0035] According to an embodiment of the present invention, Figure 1 and Figure 2As shown, the quantum state preparation unit 2 includes a laser chip 21, and the quantum state measurement chip 3 includes an end coupler 31. The laser chip 21 is used to provide continuous laser, that is, coherent state light. One input end of the end coupler 31 receives the coherent state light output by the laser chip 21, and the other input end is vacant as a vacuum state input 22. Among them, the light output port of the laser chip 21 and the input end of the end coupler 31 are three-dimensionally aligned using a preset alignment structure D1, and the preset alignment structure D1 is formed on the co-fired ceramic substrate 1. Exemplarily, the alignment structure D1 can be selected as a groove structure or a boss structure, etc.

[0036] According to the embodiment of the present invention, the end coupler 31 can be understood as a coupler located at the edge of the optical chip. The end coupler can achieve efficient transmission of optical signals by accurately aligning the optical chip and the light source, and has the advantages of high coupling efficiency and large working bandwidth.

[0037] It is understandable that the three-dimensional alignment of the end coupler 31 and the light source is the key to achieving high light coupling efficiency of the end coupler 31, because only when the light emitted by the light source (such as the laser chip 21) is accurately matched with the light mode field (mode spot) of the end coupler 31, can the reflection and scattering of the light be minimized, thereby improving the light transmission efficiency. Exemplarily, the three-dimensional alignment may include vertical alignment (ensuring that the light beam is highly aligned with the waveguide end face) and horizontal alignment (ensuring that the light beam is at the center of the waveguide end face to maximize the light coupling efficiency), as well as angular alignment (ensuring that the angle of the light beam to the waveguide axis is correct).

[0038] According to an embodiment of the present invention, based on the pre-designed alignment structure D1 on the co-fired ceramic substrate 1, the light output port of the laser chip 21 and the input end of the end coupler 31 can be three-dimensionally aligned to minimize input loss, thereby ensuring a high optical coupling efficiency between the laser chip 21 and the end coupler 31.

[0039] Therefore, the quantum random number generator 100 based on co-fired ceramic integration provided by the embodiment of the present invention realizes the photoelectric integration of the light source, the passive optical chip and the back-end microelectronic circuit by integrating the quantum state preparation unit 2, the quantum state measurement chip 3, the first processing unit 4 and the second processing unit 5 on a co-fired ceramic substrate 1, thereby improving the stability and output bandwidth of the system, and can effectively reduce the volume of the entire system of the quantum random number generator 100 while reducing the cost. In addition, by pre-designing the alignment structure D1 on the co-fired ceramic substrate 1, the light outlet of the laser chip 21 and the input end of the end coupler 31 can be three-dimensionally aligned to minimize the input loss, thereby ensuring a high optical coupling efficiency between the laser chip 21 and the end coupler 31.

[0040] According to the embodiment of the present invention, a preset groove d1 is formed on the co-fired ceramic substrate 1, the laser chip 21 is fixed in the preset groove, and the light outlet of the laser chip 21 and the end face coupler 31 are three-dimensionally aligned by the preset groove d1.

[0041] Figure 3 A perspective view of a quantum random number generator based on co-fired ceramic integration according to an embodiment of the present invention is shown. Figure 4 A quantum state preparation unit and a quantum state measurement chip according to an embodiment of the present invention are shown.

[0042] According to one embodiment of the present invention, Figure 3 and Figure 4 As shown, a preset groove d1 is formed on the co-fired ceramic substrate 1. The laser chip 21 is fixed in the preset groove d1, and the light outlet of the laser chip 21 and the end face coupler 31 are three-dimensionally aligned by the preset groove d1.

[0043] As just one example, based on the multi-layer structure and preparation process of the co-fired ceramic substrate 1, during the preparation process of the co-fired ceramic substrate 1, a preset groove d1 can be made on at least one layer of the single-piece ceramic substrate by mechanical punching / laser punching, etc., so that the light output port of the laser chip 21 and the input end of the end face coupler 31 can be three-dimensionally aligned using the preset groove d1.

[0044] Compared with the boss structure, the solution of forming a groove structure on a co-fired ceramic substrate has the advantages of simple process, less material usage, low cost and high integration.

[0045] According to an embodiment of the present invention, the depth of the preset groove d1 is determined according to the height difference between the laser chip 21 and the end face coupler 31, and the depth of the preset groove d1 enables the light outlet of the laser chip 21 and the input end of the end face coupler 31 to be aligned in the vertical direction; the fixed position of the laser chip 21 in the preset groove d1 is determined based on the maximum optical coupling efficiency between the laser chip 21 and the end face coupler 31.

[0046] According to an embodiment of the present invention, Figure 3 and Figure 4 As shown, the height difference between the laser chip 21 and the end face coupler 31 can be accurately measured first, and then the height difference can be determined as the depth of the preset groove d1, so that the light outlet of the laser chip 21 and the input end of the end face coupler 31 can be aligned in the vertical direction based on the preset groove d1, thereby ensuring that the light emitted by the laser chip 21 is aligned with the height of the waveguide end face.

[0047] According to an embodiment of the present invention, Figure 3 and Figure 4As shown, the maximum optical coupling efficiency between the laser chip 21 and the end face coupler 31 in the preset groove d1 can be determined first, and then the position corresponding to the maximum optical coupling efficiency can be determined as the fixed position of the laser chip 21, so that the light output port of the laser chip 21 and the input end of the end face coupler 31 can be aligned in the horizontal direction and angle based on the preset groove d1.

[0048] Therefore, based on the preset groove d1 formed on the co-fired ceramic substrate 1, three-dimensional alignment between the light output port of the laser chip 21 and the input end of the end coupler 31 can be achieved, thereby effectively reducing light loss and ensuring a high light coupling efficiency between the laser chip 21 and the end coupler 31.

[0049] According to an embodiment of the present invention, a method for fixing the laser chip 21 includes: placing the laser chip 21 in a preset groove d1 to achieve vertical alignment between the light outlet of the laser chip 21 and the input end of the end coupler 31; in the horizontal plane direction, moving the laser chip 21 in the preset groove d1 according to a preset step length to determine the maximum optical coupling efficiency between the laser chip 21 and the end coupler 31; determining the position corresponding to the maximum optical coupling efficiency as the fixed position of the laser chip 21, and fixing the laser chip 21 at the fixed position to achieve three-dimensional alignment between the light outlet of the laser chip 21 and the input end of the end coupler 31.

[0050] As an example, since the depth of the preset groove d1 is determined according to the height difference between the laser chip 21 and the end coupler 31, the laser chip 21 is placed in the preset groove d1, so that the light outlet of the laser chip 21 and the input end of the end coupler 31 can be aligned in the vertical direction. In the horizontal plane direction, the laser chip 21 can be clamped by the power-on fixture, and the laser chip 21 can be moved in the preset groove d1 according to the preset step length. At the same time, the electric coupling stage can be connected to the laser chip 21. Since the power-on fixture is conductive and clamps the laser chip 21, the electric coupling stage can be electrically connected to the laser chip 21, so that the optical coupling efficiency between the laser chip 21 and the end coupler 31 can be measured. By measuring the optical coupling efficiency corresponding to each position in the preset groove d1, the position corresponding to the maximum optical coupling efficiency can be found, and the position is determined as the fixed position of the laser chip 21. The laser chip 21 can be fixed at the fixed position by dispensing glue to achieve the fixation of the laser chip 21.

[0051] Preferably, the alignment errors of the light outlet of the laser chip 21 and the input end of the end coupler 31 in the front-to-back, left-to-right, and up-to-down directions need to be controlled within 50 μm, thereby ensuring efficient coupling of optical signals.

[0052] According to an embodiment of the present invention, the quantum state measurement chip 3 also includes a passive device 32, which is integrated on the quantum state measurement chip 3; the output end of the quantum state measurement chip 3 is constructed as a beveled structure so that the optical signal can be totally reflected at the output end of the quantum state measurement chip 3 to change the light output direction of the optical signal from the horizontal direction to the vertical direction.

[0053] According to an embodiment of the present invention, Figure 1-4 As shown, the quantum state measurement chip 3 also includes a passive device 32 integrated on the chip. The quantum state measurement chip 3 is used to receive the optical signal output by the end face coupler 31 and realize quantum state measurement. The quantum state measurement chip 3 can be, for example, a silicon-based optical chip. Exemplarily, the end face receiver can couple the continuous laser input by the laser chip 21 into the quantum state measurement chip 3, so that the optical signal can be output to the passive device 32 integrated on the quantum state measurement chip 3.

[0054] According to an embodiment of the present invention, based on the refractive index characteristics of the silica waveguide, the output end of the quantum state measurement chip 3 is constructed as a bevel structure, and preferably, the angle of the bevel structure can be set to 45°. The optical signal can be totally reflected at the output end of the quantum state measurement chip 3, and the light emitting direction of the optical signal is changed from the horizontal direction to the vertical direction.

[0055] According to an embodiment of the present invention, the optical signal includes a coherent state sub-signal and a vacuum state sub-signal, and the first processing unit 4 includes a first photodetector chip 41, a transimpedance amplifier 42, and a second photodetector chip 43 connected in sequence, the first photodetector chip 41 and the second photodetector chip 43 are used to receive the coherent state sub-signal and the vacuum state sub-signal output by the quantum state measurement chip 3, the first photodetector chip 41 is used to output a first electrical signal, the second photodetector chip 43 is used to output a second electrical signal, and the transimpedance amplifier 42 is used to receive a differential mode signal of the first electrical signal and the second electrical signal; wherein, the photosensitive surface of the first photodetector chip 41 is perpendicular to the light emitting direction of the coherent state sub-signal, and the electrode of the first photodetector chip 41 is horizontally bonded to the electrode of the co-fired ceramic substrate 1; the photosensitive surface of the second photodetector chip 43 is perpendicular to the light emitting direction of the vacuum state sub-signal, and the electrode of the second photodetector chip 43 is horizontally bonded to the electrode of the co-fired ceramic substrate 1.

[0056] According to an embodiment of the present invention, the first processing unit 4 is used to perform photoelectric conversion and amplification on the optical signal. Figure 1-Figure 4 As shown, the first processing unit 4 includes a first photodetector chip 41, a transimpedance amplifier 42 and a second photodetector chip 43 connected in sequence. The first photodetector chip 41 and the second photodetector chip 43 are used for photoelectric conversion, and the transimpedance amplifier 42 is used for amplifying the signal.

[0057] According to one embodiment of the present invention, the first photodetector chip 41 and the second photodetector chip 43 have the same structure, and are preferably low-noise and high-responsivity photodetector chips. The first photodetector chip 41 and the second photodetector chip 43 are used to receive the coherent state sub-signal and the vacuum state sub-signal output by the quantum state measurement chip 3, the first photodetector chip 41 is used to output the first electrical signal, the second photodetector chip 43 is used to output the second electrical signal, and the transimpedance amplifier 42 is used to receive the differential signal of the first electrical signal and the second electrical signal. Among them, the first electrical signal represents the detection result of the first photodetector chip 41 on the coherent state sub-signal and the vacuum state sub-signal, and the second electrical signal represents the detection result of the second photodetector chip 43 on the coherent state sub-signal and the vacuum state sub-signal. The difference between the first electrical signal and the second electrical signal can be determined as a differential signal, and the differential signal can be used to represent the vacuum state sub-signal.

[0058] According to one embodiment of the present invention, the photosensitive surface of the photodetector chip and its electrode are located in the same plane. If the light emitting direction of the quantum state measurement chip 3 is horizontal, the photosensitive surface of the photodetector chip needs to be along the vertical plane, and its electrode is difficult to bond with the substrate electrode. However, since the output end of the quantum state measurement chip 3 of the embodiment of the present invention is constructed as a bevel structure, the optical signal can be totally reflected at the output end of the quantum state measurement chip 3, thereby changing the light emitting direction of the optical signal from the horizontal direction to the vertical direction. Therefore, the photosensitive surface of the photodetector chip can be turned upward to receive the optical signal output by the quantum state measurement chip 3, and the electrode of the photodetector chip can be directly bonded horizontally with the substrate electrode.

[0059] It can be understood that, through the bevel structure designed at the output end of the quantum state measurement chip 3, the light output direction of the optical signal is changed from the horizontal direction to the vertical direction, so that the first photodetector chip 41 and the second photodetector chip 43 can be compactly integrated near the quantum state measurement chip 3, and at the same time, the electrodes of the first photodetector chip 41 and the second photodetector chip 43 can be directly horizontally bonded to the substrate electrodes, thereby improving the output bandwidth and reducing the system volume and noise crosstalk.

[0060] According to an embodiment of the present invention, the second processing unit 5 includes: an operational amplifier 51, an analog-to-digital converter 52, a randomness extraction circuit 53, a microcontroller unit 54 and a memory unit 55, wherein the operational amplifier 51, the analog-to-digital converter 52 and the randomness extraction circuit 53 are connected in sequence, and the output end of the transimpedance amplifier 42 is connected to the input end of the operational amplifier 51.

[0061] According to an embodiment of the present invention, the second processing unit 5 is used to collect the electrical signal representing the quantum fluctuation and to perform post-processing on the electrical signal. Figure 1-Figure 4As shown, the second processing unit 5 includes an operational amplifier 51 , an analog-to-digital converter 52 , a randomness extraction circuit 53 , a microcontroller unit 54 (MCU) and a memory unit 55 .

[0062] According to an embodiment of the present invention, Figure 1-Figure 4 As shown, the operational amplifier 51 , the analog-to-digital converter 52 and the randomness extraction circuit 53 are connected in sequence, and the output end of the transimpedance amplifier 42 is connected to the input end of the operational amplifier 51 .

[0063] According to an embodiment of the present invention, the transimpedance amplifier 42, the operational amplifier 51, the analog-to-digital converter 52, the randomness extraction circuit 53, the microcontroller unit 54 and the memory unit 55 are all connected to the electrodes of the co-fired ceramic substrate 1 by means of SMD.

[0064] According to the embodiment of the present invention, the patch connection method is used to facilitate the quantum random number generator 100 to achieve high-bandwidth, small-volume, and low-noise optoelectronic integration.

[0065] According to an embodiment of the present invention, the end coupler 31 is configured as a silicon-based inverted wedge structure.

[0066] According to the embodiment of the present invention, the silicon-based inversed-taper end coupler 31 can increase the mode field radius of the waveguide, thereby increasing the mode spot matching between the waveguide and the laser, and further improving the light coupling efficiency.

[0067] According to an embodiment of the present invention, the thermal expansion coefficient of the co-fired ceramic substrate 1 is The dielectric constant temperature coefficient of the co-fired ceramic substrate 1 is 10ppm / K~20ppm / K.

[0068] According to the embodiment of the present invention, thanks to the smaller thermal expansion coefficient and dielectric constant temperature coefficient of the co-fired ceramic substrate 1, the deformation amplitude of the co-fired ceramic substrate 1 in a high temperature environment is extremely low, which can make the optical connection between the laser chip 21, the end coupler 31, the quantum state measurement chip 3 and the photodetector chip less susceptible to the high temperature environment, thereby ensuring that the high optical coupling efficiency between the laser chip 21 and the end coupler 31 can remain stable. In addition, without affecting the optical coupling efficiency, the co-fired ceramic substrate 1 can also provide a larger operating temperature range for the quantum random number generator 100, meeting the industrial standard of -40°C to 85°C.

[0069] According to an embodiment of the present invention, the co-fired ceramic substrate 1 may be a low temperature co-fired ceramic substrate (Low Temperature Co-fired Ceramic, LTCC) or a high temperature co-fired ceramic substrate (High Temperature co-fired Ceramic, HTCC).

[0070] Figure 5 A schematic diagram showing the principle of a quantum random number generator according to an embodiment of the present invention is shown.

[0071] According to an embodiment of the present invention, Figure 5 As shown, the laser chip 21 provides continuous laser light, i.e., coherent state sub-signal , coherent state signal The quantum state measurement chip 3 enters one input end through the end coupler 31. The other input end of the quantum state measurement chip 3 is left vacant as the vacuum state sub-signal enter.

[0072] like Figure 5 As shown, the coherent state signal and vacuum state subsignal After being processed by the passive device 32 integrated on the quantum state measurement chip 3, two different quantum state lights are output, namely quantum state and quantum states .

[0073] like Figure 5 As shown, two paths of quantum state light are respectively converted into photoelectricity by the first photodetector chip 41 and the second photodetector chip 43 to generate two paths of photocurrent. Corresponding to the first electrical signal mentioned above, the photocurrent Corresponding to the second electrical signal described above, the two photocurrents are input to the transimpedance amplifier 42, which amplifies the weak high-frequency current signal and converts it into a voltage signal, which is the random signal generated by quantum fluctuations.

[0074] like Figure 5 As shown, the voltage signal output by the transimpedance amplifier 42 is still relatively weak and needs to be further amplified by the operational amplifier 51 before it can be collected and quantized by the analog-to-digital converter 52. The amplified voltage signal enters the analog-to-digital converter 52, generates raw data after conversion, and after post-processing by the randomness extraction circuit 53, the real-time generated quantum random number can be obtained. During this period, the randomness extraction circuit 53 is configured by the memory unit 55, and the micro control unit 54 is responsible for the instruction issuance and overall control of the circuit.

[0075] Reference below Figure 1-Figure 5The working principle of the quantum random number generator of the embodiment of the present invention is specifically described as follows:

[0076] Quantum fluctuations exist in the coherent state light field, which satisfies the principle of minimum uncertainty in amplitude and phase. This random number scheme is essentially to quantize and extract the coherent state quantum fluctuations. In the embodiment of the present invention, two photodetector chips are used to balance the two paths of light output by the quantum state measurement chip 3, so that randomness can be reflected.

[0077] One path of the laser chip 21 is the local oscillator light source (i.e. continuous laser) input, and the other path is vacant (i.e. vacuum state light). If we assume that the quantum states of the two input paths are ,remember After being processed by the passive device 32 on the quantum state measurement chip 3, the quantum states of the two output lights are recorded as , there are the following relations:

[0078] (1)

[0079] (2)

[0080] In formula (1)-formula (2), Vacuum state;

[0081] After photoelectric conversion, the current passing through the first photodetector chip 41 and the second photodetector chip 43 is:

[0082] (3)

[0083] (4)

[0084] In formula (3)-formula (4), is the quantum efficiency of the photodetector, Corresponding to the light intensity of the two input photoelectric detectors respectively; Added superscript "+" to represent The Hermitian conjugation of the quantum state. The current value should be equal to the product of the quantum efficiency and the light intensity. The difference between the two currents is for:

[0085] (5)

[0086] It can be proved that:

[0087] (6)

[0088] In formula (6) Corresponding quantum noise , quantum noise is reflected in the result of equilibrium detection. In the embodiment of the present invention, the noise obtained by the data acquisition and post-processing circuit The distribution is divided into two parts, quantum noise and classic noise ,Right now

[0089] (7)

[0090] Continuous laser is a coherent light source, and its average photon number is For coherent light sources, the number of photons is Poisson distribution , whose distribution is given by the following formula (8):

[0091] (8)

[0092] After the two photodetectors detect the results of photodetection with homodyne, the number of photons is It obeys the Skellam distribution, and its distribution is given by the following formula (9):

[0093] (9)

[0094] In formula (9), is the modified Bessel function; The two parameters corresponding to the average number of photons in the two light paths are also the two parameters of the Skellam distribution, which determine the shape of this distribution.

[0095] In the embodiment of the present invention, the quantum noise distribution can be obtained through the above calculation.

[0096] Classical noise in the system follows a Gaussian distribution, so we only need to measure the classical noise when there is no light input. , we can calculate the proportion of quantum noise.

[0097] The minimum entropy is calculated by calculating the quantum noise distribution The randomness is quantified by the minimum entropy, which is defined as:

[0098] (10)

[0099] In formula (10), is the probability of the most likely outcome. The random number of vacuum state fluctuations obeys the Skellam distribution, which is obtained through the aforementioned quantum noise variance , you can get , thereby calculating the minimum entropy.

[0100] In the final random number post-processing, the Toeplitz matrix algorithm based on fast Fourier transform is used, and the matrix size is , that is, the final random number of m bits can be extracted from the n-bit original quantum random number data, and the following relationship is satisfied: After the above processing, the final quantum random number can be obtained. Its randomness comes from the basic principles of quantum physics and can be verified by information theory.

[0101] In the above scheme, the minimum entropy of the original data is calculated based on the measurement results, and the measurement results can be obtained in real time inside the randomness extraction circuit 53, thereby achieving an accurate estimation of the minimum entropy. After the original data is post-processed, the final quantum random number of vacuum state fluctuations can be obtained in real time. Through the above scheme, high-speed and stable quantum random numbers can be obtained.

[0102] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

[0103] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A quantum random number generator based on co-fired ceramic integration, characterized in that: The quantum random number generator comprises: a co-fired ceramic substrate, and a quantum state preparation unit, a quantum state measurement chip, a first processing unit and a second processing unit which are integrated on the co-fired ceramic substrate and connected in sequence, wherein the quantum state preparation unit comprises a laser chip, and the quantum state measurement chip comprises an end face coupler; The laser chip is used to output an optical signal, the end coupler is used to receive the optical signal output by the laser chip, the quantum state measurement chip is used to receive the optical signal output by the end coupler and implement quantum state measurement, the first processing unit is used to perform photoelectric conversion and amplification on the optical signal to obtain an electrical signal, and the second processing unit is used to collect and post-process the electrical signal representing quantum fluctuations to obtain a quantum random number; The light outlet of the laser chip and the input end of the end face coupler are three-dimensionally aligned using a preset alignment structure, and the preset alignment structure is formed on the co-fired ceramic substrate; the output end of the quantum state measurement chip is constructed as a beveled structure so that the optical signal can be totally reflected at the output end of the quantum state measurement chip to change the light output direction of the optical signal from a horizontal direction to a vertical direction.

2. The quantum random number generator according to claim 1, characterized in that: A preset groove is formed on the co-fired ceramic substrate, the laser chip is fixed in the preset groove, and the light outlet of the laser chip and the end face coupler are three-dimensionally aligned by using the preset groove.

3. The quantum random number generator according to claim 2, characterized in that: The depth of the preset groove is determined according to the height difference between the laser chip and the end coupler, and the depth of the preset groove enables the light outlet of the laser chip and the input end of the end coupler to be aligned in the vertical direction; The fixed position of the laser chip in the preset groove is determined based on the maximum light coupling efficiency between the laser chip and the end face coupler.

4. The quantum random number generator according to claim 3, characterized in that: The method for fixing the laser chip comprises: Placing the laser chip in the preset groove to achieve vertical alignment between the light outlet of the laser chip and the input end of the end face coupler; In a horizontal plane direction, moving the laser chip in the preset groove according to a preset step length to determine the maximum optical coupling efficiency between the laser chip and the end face coupler; The position corresponding to the maximum optical coupling efficiency is determined as the fixed position of the laser chip, and the laser chip is fixed at the fixed position to achieve three-dimensional alignment between the light outlet of the laser chip and the input end of the end face coupler.

5. The quantum random number generator according to any one of claims 1 to 4, characterized in that: The quantum state measurement chip also includes passive components, and the passive components are integrated on the quantum state measurement chip.

6. The quantum random number generator according to claim 5, characterized in that: The optical signal includes a coherent state sub-signal and a vacuum state sub-signal, The first processing unit includes a first photodetector chip, a transimpedance amplifier, and a second photodetector chip connected in sequence, the first photodetector chip and the second photodetector chip are used to receive the coherent state sub-signal and the vacuum state sub-signal output by the quantum state measurement chip, the first photodetector chip is used to output a first electrical signal, the second photodetector chip is used to output a second electrical signal, and the transimpedance amplifier is used to receive a differential mode signal of the first electrical signal and the second electrical signal; Among them, the photosensitive surface of the first photodetector chip is perpendicular to the light emitting direction of the coherent state sub-signal, and the electrode of the first photodetector chip is horizontally bonded to the electrode of the co-fired ceramic substrate; the photosensitive surface of the second photodetector chip is perpendicular to the light emitting direction of the vacuum state sub-signal, and the electrode of the second photodetector chip is horizontally bonded to the electrode of the co-fired ceramic substrate.

7. The quantum random number generator according to claim 6, characterized in that: The second processing unit includes: an operational amplifier, an analog-to-digital converter, a randomness extraction circuit, a microcontroller unit and a memory unit, wherein the operational amplifier, the analog-to-digital converter and the randomness extraction circuit are connected in sequence, and the output end of the transimpedance amplifier is connected to the input end of the operational amplifier.

8. The quantum random number generator according to claim 7, characterized in that: The transimpedance amplifier, the operational amplifier, the analog-to-digital converter, the randomness extraction circuit, the microcontroller unit and the memory unit are all connected to the electrodes of the co-fired ceramic substrate by means of patches.

9. The quantum random number generator according to any one of claims 1 to 4, characterized in that: The end coupler is configured as a silicon-based inverted wedge structure.

10. The quantum random number generator according to any one of claims 1 to 4, characterized in that: The thermal expansion coefficient of the co-fired ceramic substrate is The dielectric constant temperature coefficient of the co-fired ceramic substrate is 10ppm / K~20ppm / K.

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