Hybrid integrated quantum random number generator based on silicon dioxide waveguide

Abstract

This technology discloses a hybrid integrated quantum random number generator based on silica waveguide, including a random number optical structure, the random number optical structure includes a hybrid integrated substrate, a laser chip 1, a detector chip 1 and a PLC waveguide are fixed on the hybrid integrated substrate, and a 50:50 beam splitting module 2, a waveguide delay module and a 50:50 beam combining module 2 are provided on the PLC waveguide, the 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is provided on one of the waveguide optical paths; the PLC waveguide is a silicon-based silica waveguide. This technology can ultimately realize a low-cost, high-stability, small-volume quantum random number generator, thereby promoting the expansion and development of the application field of quantum random number generators.

Description

Technical Field

[0001] The present technology belongs to the field of quantum random numbers, and specifically relates to a hybrid integrated quantum random number generator based on silicon dioxide waveguide. Background Art

[0002] Random numbers are one of the important resources of cryptography. Both classical cryptography and quantum cryptography have very strict requirements on the randomness of random numbers, which even directly determines the security of most cryptographic systems. In addition, random numbers are also widely used outside of cryptography, including in sampling statistics, Monte-Carlo simulation, and some computational sciences, playing a very important role.

[0003] At present, based on the characteristics of the generation method and the output sequence, the random number generation method can be divided into two categories: pseudo-random number generator and physical random number generator. Among them, the pseudo-random number generator is generally based on a preset mathematical algorithm, with external information such as the system time as the seed, and is implemented together with a computer. This random number generator can output a pseudo-random number sequence at a very fast rate, and the algorithm ensures that the output sequence has certain statistical characteristics. However, since pseudo-random numbers are generated based on a deterministic algorithm, the source of their randomness is only the randomness of the input seed, so when it is used frequently, it can theoretically be predicted by statistical analysis of the generated random numbers.

[0004] Physical random numbers are different. Their randomness is based on the randomness of some non-deterministic objective physical phenomena, including atmospheric noise, electronic noise, circuit jitter, etc. These random number generators generate random numbers by detecting the results of these physical phenomena. At the same time, if these physical phenomena are quantum phenomena, this type of physical random number generator is called a quantum random number generator. These physical phenomena include quantum physical processes such as vacuum fluctuations, phase noise, and radiation decay. Due to the intrinsic randomness of quantum mechanics in quantum physical processes, quantum random numbers are generally considered to be truly random and cannot be predicted, making them an ideal random number generator.

[0005] With the introduction of this concept, the theoretical and experimental work on quantum random number generators has made great progress. However, the existing quantum random number generators are generally based on separate optical device systems, and still have problems such as large size, high power consumption, and high price, and have not yet been widely used.

[0006] As we all know, integrated optics is to integrate optical components on the same substrate and interconnect the lines through high-refractive-index optical waveguides to solve the problems of large size, poor stability, and high price of traditional optical systems. Among the many optical waveguide materials, silicon-based silica planar lightwave circuit waveguide (PLC) has become one of the preferred routes for quantum random number integration due to its low price and mature manufacturing process. However, at the same time, since active devices such as lasers and detectors cannot be realized on PLC waveguides, it is necessary to use hybrid integration to combine the lasers and detectors required by the random number generator with the PLC waveguide results, so as to complete the design and production of the quantum random number generator. Summary of the invention

[0007] The technical problem to be solved by the present technology is to provide a hybrid integrated quantum random number generator based on silicon dioxide waveguide in view of the deficiencies of the above-mentioned prior art. The hybrid integrated quantum random number generator based on silicon dioxide waveguide can ultimately realize a low-cost, high-stability, and small-volume quantum random number generator, thereby promoting the expansion and development of the application field of quantum random number generators.

[0008] In order to achieve the above technical objectives, the technical solution adopted by this technology is:

[0009] A hybrid integrated quantum random number generator based on silica waveguide, comprising a random number optical structure, the random number optical structure comprising a hybrid integrated substrate, a laser chip 1, a detector chip 1 and a PLC waveguide are fixed on the hybrid integrated substrate, a 50:50 beam splitting module 2, a waveguide delay module and a 50:50 beam combining module 2 are arranged on the PLC waveguide, the 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is arranged on one of the waveguide optical paths; the PLC waveguide is a silicon-based silica waveguide;

[0010] The light pulse emitted by the laser chip 1 is used to be transmitted to the 50:50 beam splitting module 2 in the PLC waveguide. One end of the 50:50 beam splitting module 2 is used to send the light pulse to the 50:50 beam combining module 2 through the waveguide delay module on the waveguide optical path, and the other end is used to send the light pulse to the 50:50 beam combining module 2 through the waveguide optical path. The 50:50 beam combining module 2 is used to combine the two received light pulses and transmit them to the detector chip 1.

[0011] As a technical solution for further improvement of the present technology, the 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is provided on one of the waveguide optical paths and an equal-arm interferometer is provided on the other waveguide optical path. The equal-arm interferometer includes a 50:50 beam splitting module 1 and a 50:50 beam combining module 1. The 50:50 beam splitting module 1 is connected to the 50:50 beam combining module 1 through a waveguide upper arm and a waveguide lower arm, respectively. The waveguide upper arm and the waveguide lower arm have the same length and a phase adjustment module is provided on the waveguide upper arm and / or the waveguide lower arm.

[0012] As a further improved technical solution of the present technology, a lens 1 and a lens 2 are also fixed on the hybrid integrated substrate; the lens 1 is located between the laser chip 1 and the PLC waveguide, and the lens 2 is located between the PLC waveguide and the detector chip 1;

[0013] The light pulse emitted by the laser chip one is used to be transmitted to the lens one through the spatial light path. The lens one is used to transmit the light pulse into the PLC waveguide through the spatial light path. The light pulse then passes through the waveguide light path in the PLC waveguide and enters the 50:50 beam splitting module two. The 50:50 beam combining module two is used to transmit the light pulse to the end of the PLC waveguide through the waveguide light path. The light pulse then passes through the spatial light path and the lens two and enters the detector chip one.

[0014] The beneficial effects of this technology are: This technology proposes a quantum random number generator structure based on silicon-based silica waveguide hybrid integration. Using this structure, the volume, cost and power consumption of existing quantum random number generators can be reduced, which is conducive to greatly broadening the use scenarios and commercial application markets of quantum random number generators. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the random number optical structure of the present technical embodiment Figure 1 .

[0016] Figure 2 This is a schematic diagram of the structure of a quantum random number generator according to an embodiment of the present technology.

[0017] Figure 3 Schematic diagram of the random number optical structure of the present technical embodiment Figure 2 . DETAILED DESCRIPTION

[0018] According to the following Figures 1 to 3 The specific implementation methods of this technology are further described as follows:

[0019] like Figure 1As shown, a hybrid integrated quantum random number generator based on silica waveguide includes a random number optical structure, which includes a hybrid integrated substrate, on which a laser chip 1, a detector chip 1 and a PLC waveguide are fixed, and the PLC waveguide is provided with a 50:50 beam splitting module 2, a waveguide delay module and a 50:50 beam combining module 2. The 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is provided on one of the waveguide optical paths. The PLC waveguide is a silicon-based silica waveguide. The waveguide delay module is used for optical delay of light pulses, and is generally a long waveguide structure on the PLC waveguide chip. The delay amount is controlled by controlling the waveguide length. The light pulse emitted by the laser chip 1 is used to be transmitted to the 50:50 beam splitting module 2 in the PLC waveguide. One end of the 50:50 beam splitting module 2 is used to send optical pulses to the 50:50 beam combining module 2 through the waveguide delay module on the waveguide optical path, and the other end is used to send optical pulses to the 50:50 beam combining module 2 through the waveguide optical path. The 50:50 beam combining module 2 is used to combine the two received optical pulses and transmit them to the detector chip 1.

[0020] Lens 1 and lens 2 are also fixed on the hybrid integrated substrate of this embodiment; lens 1 is located between laser chip 1 and PLC waveguide. Lens 2 is located between PLC waveguide and detector chip 1. The light pulse emitted by laser chip 1 is used to be transmitted to lens 1 through a spatial optical path, and lens 1 is used to transmit the light pulse to the PLC waveguide through a spatial optical path, and the light pulse then passes through the waveguide optical path in the PLC waveguide and enters the 50:50 beam splitting module 2. The 50:50 beam combining module 2 is used to transmit the light pulse to the end of the PLC waveguide through the waveguide optical path, and the light pulse then enters the detector chip 1 through the spatial optical path and lens 2.

[0021] like Figure 3 As shown, further, a waveguide delay module is provided on a waveguide optical path between the 50:50 beam splitting module 2 and the 50:50 beam combining module 2 in the random number optical structure of this embodiment, and an equal-arm interferometer can also be provided on the other waveguide optical path, the equal-arm interferometer comprises a 50:50 beam splitting module 1 and a 50:50 beam combining module 1, the 50:50 beam splitting module 1 is connected to the 50:50 beam combining module 1 through a waveguide upper arm and a waveguide lower arm respectively, the waveguide upper arm and the waveguide lower arm have the same length and a phase adjustment module is provided on the waveguide upper arm and / or the waveguide lower arm.

[0022] for Figure 2 and Figure 3 , the implementation steps are as follows:

[0023] (1) A driving circuit module is used to provide voltage drive to the laser chip 1, so that the laser chip 1 works in a gain switching mode and emits a series of phase-independent optical pulses.

[0024] (2) The light pulse from the laser chip 1 passes through the lens 1 and enters the PLC optical waveguide, where it is then transmitted and enters the 50:50 beam splitting module 2.

[0025] (3) An equal-arm MZ interferometer is composed of a 50:50 beam splitting module 1, a phase adjustment module and a 50:50 beam combining module 1. By controlling the length of the waveguide delay module, it is ensured that after the light pulse is split by the 50:50 beam splitting module 1, there is a fixed difference in the optical path length between the upper and lower waveguide arms and the 50:50 beam combining module 1. This equal-arm MZ is used to adjust the light intensity of the light pulse transmitted through the MZ interferometer. Here, a unequal-arm MZ interferometer is composed of a 50:50 beam splitting module 2, a waveguide delay module, a 50:50 beam combining module 2 and the equal-arm MZ interferometer mentioned above. By controlling the length of the waveguide delay module, it is ensured that after the light pulse is split by the 50:50 beam splitting module 2, there is a fixed difference in the optical path length between the upper and lower arms and the 50:50 beam combining module 2. The inherent optical path difference is generally the period of the light pulse emitted by the laser chip, and also includes integer multiples of the period, so that the front and rear light pulses emitted by the laser chip can interfere with each other.

[0026] (4) According to the arm length difference of the unequal-arm interferometer mentioned above, the light pulses of the laser chip 1 participating in the interference interfere at the 50:50 beam combining module 2, and the output light intensity signal is:

[0027]

[0028] Here I represents the output light intensity, I 1 and I 2 represents the intensity of the light pulse involved in the interference, θ 1 and θ 2 They represent the phases of the previous and next pulses respectively. Since the phases of the independent light pulses emitted by the laser chip are completely unrelated, and since the emission of the light pulses is based on spontaneous radiation, the phases are completely random. At this time, the output intensity of the interference result is completely random, and since the spontaneous radiation phenomenon is a quantum phenomenon, this randomness is quantum randomness.

[0029] (5) In this random number generator, this embodiment defines interference visibility as follows:

[0030]

[0031] in:

[0032]

[0033] So we have:

[0034]

[0035] The interference visibility is related to the random number production efficiency of the final random number generator. In this embodiment, it is hoped that V = 1 in the system. However, since the waveguide paths of the pulses participating in the interference are different, the intensity I 1 and I 2 In actual situations, there may be deviations. Here, this embodiment uses the phase adjustment module in the equal-arm MZ interferometer to adjust the phase of I 1 and I 2 The effect of the strength is reduced so that the interference visibility remains at 1.

[0036] (6) The random light intensity signal after interference will pass through the waveguide through the 50:50 beam combining module 2, and then through the lens 2 for beam focusing.

[0037] Entering the detector chip, the detector chip detects the light intensity of the light pulse and transmits the detection analog signal result to the analog-to-digital conversion module through wires. After being converted into a digital signal, it enters the post-processing module. The post-processing module runs the pre-made post-processing algorithm, extracts random numbers, and then outputs the random number signal through the random number output interface.

[0038] Figure 1 The implementation steps and Figure 3 Similarly, here we will Figure 3 The equal-arm MZ interferometer composed of a 50:50 beam splitting module, a phase adjustment module and a 50:50 beam combining module is omitted. The efficiency of random number generation may be reduced because the intensity of the optical pulses participating in the interference cannot be adjusted.

[0039] exist Figure 1 , Figure 3 In the optical path, the dotted line represents the spatial optical path, and the solid line represents the waveguide optical path. In order for the random number generator to work properly, the system also requires corresponding external drive circuit modules and post-processing modules, such as Figure 2 As shown, Figure 2 Schematic diagram of the overall structure of the quantum random number generator. Figure 2 The solid lines in the middle represent metal lines such as driving lines or data transmission lines.

[0040] exist Figure 2In the random number optical structure, the driving circuit module provides driving signals for active devices including laser chip 1, detector chip 1 and phase adjustment module. The analog-to-digital conversion module converts the analog electrical signal detected by the detector chip 1 into a digital signal and sends it to the post-processing module. The post-processing module is generally a data processing chip such as an ASIC chip or an FPGA chip. The post-processing module performs post-processing on the received digital signal and then transmits the generated random number through the random number output interface for user use. Generally, the random number output interface includes common data interfaces such as network port, PCI-e, and USB interface.

[0041] In summary, this technology proposes a quantum random number generator structure based on silicon-based silica waveguide hybrid integration. Using this structure, the volume, cost and power consumption of existing quantum random number generators can be reduced, which is conducive to greatly broadening the use scenarios and commercial application markets of quantum random number generators.

[0042] The protection scope of the present technology includes but is not limited to the above embodiments. The protection scope of the present technology shall be based on the claims. Any replacement, deformation, and improvement of the present technology that can be easily thought of by technicians in this field shall fall within the protection scope of the present technology.

Claims

1. A hybrid integrated quantum random number generator based on silicon dioxide waveguide, characterized in that: It comprises a random number optical structure, the random number optical structure comprises a hybrid integrated substrate, a laser chip 1, a detector chip 1 and a PLC waveguide are fixed on the hybrid integrated substrate, a 50:50 beam splitting module 2, a waveguide delay module and a 50:50 beam combining module 2 are arranged on the PLC waveguide, the 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is arranged on one of the waveguide optical paths; the PLC waveguide is a silicon-based silica waveguide; The optical pulse emitted by the laser chip 1 is used to be transmitted to the 50:50 beam splitting module 2 in the PLC waveguide. One end of the 50:50 beam splitting module 2 is used to send the optical pulse to the 50:50 beam combining module 2 through the waveguide delay module on the waveguide optical path, and the other end is used to send the optical pulse to the 50:50 beam combining module 2 through the waveguide optical path. The 50:50 beam combining module 2 is used to combine the two received optical pulses and transmit them to the detector chip 1. The 50:50 beam splitting module 2 is connected to the 50:50 beam combining module 2 through two waveguide optical paths, and a waveguide delay module is provided on one of the waveguide optical paths and an equal-arm interferometer is provided on the other waveguide optical path. The equal-arm interferometer includes a 50:50 beam splitting module 1 and a 50:50 beam combining module 1. The 50:50 beam splitting module 1 is connected to the 50:50 beam combining module 1 through a waveguide upper arm and a waveguide lower arm, respectively. The waveguide upper arm and the waveguide lower arm have the same length, and a phase adjustment module is provided on the waveguide upper arm and / or the waveguide lower arm.

2. The hybrid integrated quantum random number generator based on silicon dioxide waveguide according to claim 1, characterized in that: The hybrid integrated substrate is also fixed with a lens 1 and a lens 2; the lens 1 is located between the laser chip 1 and the PLC waveguide, and the lens 2 is located between the PLC waveguide and the detector chip 1; The light pulse emitted by the laser chip one is used to be transmitted to the lens one through the spatial light path. The lens one is used to transmit the light pulse into the PLC waveguide through the spatial light path. The light pulse then passes through the waveguide light path in the PLC waveguide and enters the 50:50 beam splitting module two. The 50:50 beam combining module two is used to transmit the light pulse to the end of the PLC waveguide through the waveguide light path. The light pulse then passes through the spatial light path and the lens two and enters the detector chip one.

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