Vacuum state quantum random entropy source chip and random number sequence generation method

Abstract

The invention discloses a vacuum-state quantum random entropy source chip and a random number sequence generation method, and belongs to the technical field of vacuum-state quantum random entropy sources and quantum integrated chips. A monolithic integrated chip of a light source, a beam splitter module and a balanced homodyne detection module is designed, the beam splitter module is formed by connecting multiple stages of beam riffles in series, each beam riffle comprises a first port, a second port and two output ends, the first port of the first-stage beam riffle receives local oscillator laser emitted by the light source, and the second port of the second-stage beam riffle receives local oscillator laser emitted by the balanced homodyne detection module. The second port of each level of light beam riffle inputs a vacuum state, and split laser carrying a vacuum state signal output by the output end of each light beam riffle is used as an input signal of the first port of the next level of light beam riffle; in use, the multi-channel quantum random number sequence can be generated by starting the light source. The system can meet the application requirements of small size, low cost, stable performance and high reliability, has the advantages of high confidentiality, high speed, multiple channels, high integration and the like, and can meet more application scenes.

Description

Technical Field

[0001] The present invention belongs to the field of quantum integrated chip technology, and relates to a vacuum state quantum random entropy source technology, and in particular to a vacuum state quantum random entropy source chip and a random number sequence generation method. Background Art

[0002] Random numbers have crucial applications in numerous fields, including secure communications, cryptography, numerical simulation, gaming, and random sampling. True random number generators (TRNGs) measure certain unpredictable random physical processes and can extract random values ​​from the measurement results or directly use them as a sequence of true random numbers. Common TRNGs include those based on chaotic noise, thermal noise in electronic devices, radioactive decay, and optical quantum random number generators, all of which have high security application value.

[0003] Quantum random number generators (QNRGs) generate true random numbers based on the principles of quantum physics. The fundamental physical processes of quantum mechanics possess intrinsic randomness that is absent from classical physics. They can serve as a true source of random entropy, generating random numbers that are highly irreproducible, unpredictable, and unbiased. They are key components in quantum communication systems. Entropy sources can be categorized into single-photon path selection, vacuum fluctuations, photon arrival times, photon number distribution, laser phase fluctuations, and amplified spontaneous emission noise.

[0004] However, these schemes generate quantum random numbers at a low speed and with a small capacity (mainly due to the single channel), and most quantum random number generators rely on bulky and costly discrete optical devices and complex optical path systems, which have low economic practicality, are not conducive to miniaturization and integration, and the stability of the resulting systems is poor. The quantum random entropy source based on the chaotic cavity has low integration and non-real-time output, which limits the application scenarios.

[0005] To sum up, the defects of the existing technology are: the current quantum random number generator is large in size, high in power consumption, expensive, low in speed, small in capacity, poor in stability, and low in integration, which seriously limits the application scenarios of random numbers.

[0006] Topological photonics is a cutting-edge research field focused on exploring various physical mechanisms and optical phenomena in topological photonic structures, laying the foundation for innovative applications of optical materials and photonic devices. Among the most important applications in this field is the design of on-chip optical waveguides and beam splitters. By leveraging the unique properties of topologically protected optical modes, robust transmission of optical states and specialized functional applications can be achieved, addressing issues that are difficult to overcome with conventional photonic device design principles. However, there is currently no research on how to utilize the principles of topological photonics to realize large-scale, multi-channel, and highly integrated quantum random entropy sources. Summary of the Invention

[0007] The present invention provides a vacuum state quantum random entropy source based on a large-scale multi-channel topological photonic circuit, which is used to solve the defects of low speed, single channel, poor stability and low integration in the existing technology for generating quantum random numbers, and realize large-scale multi-channel quantum random number generation.

[0008] The present invention provides a method for generating a multi-channel quantum random number sequence, which utilizes the above-mentioned vacuum state quantum random entropy source to quickly generate a quantum random number sequence through multiple channels, thereby improving the application scenarios of random numbers.

[0009] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: On the one hand, the present invention provides a vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit, characterized by comprising: A monolithically integrated light source for providing local oscillator laser; A beam splitter module is composed of a plurality of beam splitters connected in series, each of which includes a first port for inputting a local oscillator laser, a second port for inputting a vacuum laser, and two output ports. The beam splitter is used to split the local oscillator laser inputted at the first port and the vacuum state inputted at the second port into two split laser beams with the same energy and carrying vacuum state signals, which are outputted from the two output ports respectively. The first port of the first-stage beam splitter receives the local oscillator laser emitted by the light source, and the second port of each stage beam splitter inputs the vacuum state. The split laser beams carrying vacuum state signals outputted from the output port of each beam splitter serve as input signals to the first port of the next-stage beam splitter respectively. The balanced homodyne detection module is connected to the two output ends of the last-stage beam splitter and is used to generate quantum random numbers through balanced homodyne detection technology.

[0010] Furthermore, the beam splitter module is composed of 2-10 levels of beam splitters connected in series.

[0011] Furthermore, the beam splitter includes two valley photonic crystals, and the two valley photonic crystals have different topological invariants, thereby forming a topological photonic waveguide circuit with unidirectional optical path propagation at the boundary. The topological photonic waveguide circuit includes a first incident optical path, a second incident optical path, a first splitting optical path, a second splitting optical path and two output optical paths. The entrance of the first incident optical path corresponds to the first port, and the entrance of the second incident optical path corresponds to the second port. The first incident optical path and the second incident optical path are linearly coaxial and in opposite directions, so that their exits converge to form a splitting point. The first splitting optical path and the second splitting optical path are symmetrically connected at the splitting point with the first incident optical path. The entrances of the two output optical paths are respectively connected to the first splitting optical path and the second splitting optical path, and the exits of the two output optical paths correspond to the two output ends respectively.

[0012] Furthermore, the valley photonic crystal is formed by preparing a periodically distributed low refractive index medium layer within a high refractive index medium layer.

[0013] Furthermore, the material of the high refractive index dielectric layer includes silicon, germanium, InP, GaAs, and SiN, and the material of the low refractive index dielectric layer includes air, silicon oxide, organic matter, and photoresist.

[0014] Furthermore, the unit cell of the valley photonic crystal is rhombus-shaped, and two low-refractive-index medium holes are opened in the rhombus-shaped unit cell. The areas of the two low-refractive-index medium holes are different, and two types of valley photonic crystals are formed by exchanging the areas of the two low-refractive-index medium holes.

[0015] Furthermore, the high refractive index medium layer is prepared on a substrate, and the low refractive index medium hole is prepared in the high refractive index medium layer.

[0016] Furthermore, the light source is a continuous wave laser.

[0017] Furthermore, the balanced homodyne detection module includes: Two photodetectors are connected to the two output ends of the last-stage beam splitter, respectively, to convert the optical signals at the two output ends into electrical signals; a subtractor, connected to the two photodetectors, for subtracting the current signals of the two photodetectors to obtain a differential signal; a transimpedance amplifier for amplifying the differential signal; and Analog-to-digital converter, used to extract the quantum random number sequence generated by vacuum fluctuations.

[0018] On the other hand, the present invention provides a method for generating a multi-channel quantum random number sequence, using the above-mentioned vacuum state quantum random entropy source chip, the generation method comprising the following steps: Start the light source and emit local oscillator laser; The local oscillator laser enters the first port of the first-stage beam splitter and is split 3dB into two split laser beams carrying vacuum state signals by the first-stage beam splitter. The two split laser beams carrying vacuum state signals are split 3dB again by two second-stage beam splitters respectively. The two split laser beams carrying vacuum state signals output from the two output ends of each last-stage beam splitter are both extracted through the corresponding balanced homodyne detection module to extract the quantum random number sequence generated by vacuum fluctuations, forming the generation of multi-channel quantum random number sequences.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention is based on a large-scale multi-channel topological photonic circuit. It creates a large-capacity quantum random number generator through a multiplexing scheme of balanced homodyne detector measurements, and encapsulates all optoelectronic modules in an independent device. The resulting vacuum state quantum entropy source can meet the application requirements of small size, low cost, stable performance, and high reliability, and has the advantages of high confidentiality, high speed, multi-channel, and high integration.

[0020] Taking the output end of the topological photonic waveguide circuit as the new first port, each new input end can be expanded to form a new second port and two output ends. The newly formed output end can be further expanded as a new first port. And so on, the topological photonic circuit can be continuously expanded according to different application requirements to form a large-capacity vacuum quantum random entropy source with multiple vacuum state input channels and multiple output channels, which can meet more application scenarios.

[0021] According to the vacuum state quantum random entropy source based on a large-scale multi-channel topological photonic circuit in accordance with the embodiment of the present invention, a large-capacity quantum random number generator is created by a multiplexing scheme of balanced homodyne detector measurements, and all optoelectronic modules are encapsulated in an independent device. The ultimately realized vacuum state quantum entropy source can meet the application requirements of small size, low cost, stable performance, and high reliability, and has the advantages of high confidentiality, high speed multi-channel, high integration, etc., and can meet more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a schematic diagram of the structure of a vacuum state quantum random entropy source based on a large-scale multi-channel topological photonic circuit provided by an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the structure of a single beam splitter in the beam splitter module provided in an embodiment of the present invention, where the purple dotted line represents the topological waveguide path.

[0025] Figure 3 for Figure 2 Schematic diagram of the valley boundary formed by the combination of a single first-type valley photonic crystal and a second-type valley photonic crystal.

[0026] Figure 4 for Figure 2 Schematic diagram of the topological photonic waveguide circuit in a single beam splitter.

[0027] Figure 5 This is a diagram of the energy band extremes of the valley photonic crystal in the topological photonic waveguide circuit according to an embodiment of the present invention.

[0028] Figure 6 The embodiment of the present invention provides Figure 1 Transmission spectrum simulation results of the topological photonic circuit structure shown.

[0029] Figure 7 Schematic diagram of the structure of a balanced homodyne detection module provided in an embodiment of the present invention.

[0030] 100 - beam splitter module, 101 - first port, 102 - second port, 103 - third port, 104 - fourth port; 110 - topological photonic waveguide circuit, 111 - first incident optical path, 112 - second incident optical path, 113 - first splitting optical path, 114 - second splitting optical path, 115 - first output optical path, 116 - second output optical path, 117 - splitting point; 120 - first-stage beam splitter, 121 - first-stage vacuum input, 130 - second-stage beam splitter, 131 - second-stage vacuum input, 140 - third-stage beam splitter, 141 - third-stage vacuum input; 150 - first-stage valley photonic crystal, 151 - first air hole, 152 - second air hole, 160 - second-stage valley photonic crystal, 170 - valley boundary; 200-Balanced homodyne detection module; DETAILED DESCRIPTION The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0033] Example 1: Figure 1 As shown, the present invention provides a vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit, comprising: A monolithically integrated light source for providing local oscillator laser; The beam splitter module 100 is composed of a plurality of beam splitters connected in series. The beam splitter includes a first port 101 for inputting a local oscillator laser, a second port 102 for inputting a vacuum laser, and two output ports (a third port 103 and a fourth port 104). The beam splitter is used to split the local oscillator laser inputted into the first port 101 and the vacuum state inputted into the second port 102 into two split laser beams with the same energy and carrying vacuum state signals, which are outputted from the two output ports respectively. The first port 101 of the first-stage beam splitter 120 receives the local oscillator laser emitted by the light source, and the second port 102 of each stage beam splitter inputs the vacuum state. The split laser beams carrying vacuum state signals outputted from the output ports of each beam splitter (the third port 103 and the fourth port 104) serve as the input signals of the first port 101 of the next-stage beam splitter. The balanced homodyne detection module 200 is connected to the two output ends of the last-stage beam splitter and is used to generate quantum random numbers through balanced homodyne detection technology.

[0034] The present invention creatively combines multiple levels of beam splitters in series to form a binary tree structure. The split laser and vacuum state output from the output end of the upper-level beam splitter are respectively used as input signals and input from the first port 101 of the lower-level beam splitter. The second port 102 is left vacant and serves as a vacuum state light input end. For each additional beam splitter, a new vacuum state light input end is added. A balanced homodyne detection module 200 is set at the last beam splitter to extract the quantum random number sequence generated by vacuum fluctuations and generate random numbers. Since the present invention uses a single laser beam for multi-level 3dB splitting, it can ensure that the range of direct random number sequences in different channels is the same and does not interfere with each other. This makes the present invention a large-capacity vacuum quantum random entropy source with multiple vacuum state input channels and multiple output channels. It has the advantages of high confidentiality, high speed, multi-channel, high integration, etc., and can meet more application scenarios.

[0035] When applied, the light source, beam splitter module 100 and balanced homodyne detection module 200 are encapsulated in an independent device, and the final vacuum state quantum entropy source can meet the application requirements of small size, low cost, stable performance and high reliability.

[0036] like Figure 1 As shown, exemplarily, the present invention provides a four-channel vacuum state quantum random entropy source, the beam splitter module 100 is composed of three-stage beam splitters in series, the first-stage beam splitter 120, the second-stage beam splitter 130, and the third-stage beam splitter 140 are 1, 2, and 4 respectively; the first port 101 of the first-stage beam splitter 120 is connected to the local oscillator laser emitted by the light source, the second port 102 of the first-stage beam splitter 120 is connected to the first-stage vacuum input 121, the third port 103 and the fourth port 104 of the first-stage beam splitter 120 are connected to the first port 101 of the two second-stage beam splitters 130, and the two second-stage beam splitters 140 are connected to the first port 101 of the second-stage beam splitter 130. The second port 102 of the splitter 130 is connected to a new second-stage vacuum input 131. Similarly, the third port 103 and the fourth port 104 of each second-stage beam splitter 130 are respectively connected to a third-stage beam splitter 140. The two output ends (third port 103 and fourth port 104) of each third-stage beam splitter 140 are connected to a balanced homodyne detection module 200. The balanced homodyne detection module 200 measures the vacuum fluctuation noise at the two output ends to obtain a random number sequence. This embodiment has four balanced homodyne detection modules 200 to measure the output ends of the four third-stage beam splitters 140, thereby achieving four-channel measurement.

[0037] The second port in each level of the beam splitter of the present invention is left vacant as a vacuum state, but cannot be omitted; the first-level vacuum input 121 of the first-level beam splitter 120 has a random influence on the input of the second-level beam splitter 130, and similarly, the second-level vacuum input 131 also has a random influence on the input of the third-level beam splitter 140.

[0038] It should be noted that the number of levels of the beam splitter is selected according to the number of channels. The above description is only an example, and it can generally be 2-10 levels.

[0039] like Figure 2 and Figure 3 As shown, the beam splitter includes two valley photonic crystals, Figure 3 The diagram of the valley boundary 170 formed by a single first valley photonic crystal 150 and a second valley photonic crystal 160 is shown in FIG. The black arrow indicates the direction of light propagation. The two valley photonic crystals have different topological invariants, thereby forming a topological photonic waveguide circuit 110 with unidirectional light propagation at the boundary. The schematic diagram of the topological photonic waveguide circuit 110 is shown in FIG. Figure 4As shown, the topological photonic waveguide circuit 110 includes a first incident light path 111, a second incident light path 112, a first splitting light path 113, a second splitting light path 114 and two outgoing light paths. The first incident light path 111 and the second incident light path 112 are coaxially arranged and in opposite directions, so that the outlets of the first incident light path 111 and the second incident light path 112 converge in the middle to form a splitting point 117, and the two outgoing light paths are a first outgoing light path 115 and a second outgoing light path 116, respectively. The first outgoing light path 115 and the second outgoing light path 116 are parallel to each other and to the first incident light path, and the first outgoing light path 115 and the second outgoing light path 116 are parallel to each other and to the first incident light path, and the first outgoing light path 115 and the second outgoing light path 116 are parallel to each other and to the first incident light path. The optical paths are mirror-symmetrical; the entrance of the first incident optical path 111 corresponds to the first port 101, the first split optical path 113 and the second split optical path 114 are symmetrically arranged with respect to the first incident optical path 111, the entrances of the first split optical path 113 and the second split optical path 114 are both connected to the splitting point 117, the entrances of the two outgoing optical paths are respectively connected to the exits of the first split optical path 113 and the second split optical path 114, the exits of the two outgoing optical paths respectively correspond to the two output ends, the second incident optical path 112 linearly coincides with the first incident optical path 111 and has an opposite propagation direction, and is arranged at the other opposite end, and the entrance end of the second incident optical path 112 serves as the second port 102.

[0040] The present invention realizes unidirectional propagation of optical paths through valley Hall topology by designing two valley photonic crystals, realizes ideal 3dB power splitting through the symmetry of the first splitting optical path 113 and the second splitting optical path 114, and has good robustness to dimensional errors; and for each additional beam splitter in the present invention, a corresponding second port 102 will be added, thereby forming a large-capacity vacuum quantum random entropy source with multiple vacuum state input channels and multiple output channels.

[0041] Exemplarily, the valley photonic crystal is formed by preparing a second dielectric layer with a small refractive index and a periodic distribution in the first dielectric layer. Specifically, the first dielectric layer is made of silicon material, and the second dielectric layer is air holes; or The first dielectric layer is metal, and the second dielectric layer is silicon dioxide or titanium dioxide.

[0042] like Figure 3As shown, in the present invention, the unit cell of the valley photonic crystal is a rhombus, and two equilateral triangular second dielectric layers are provided in the rhombic unit cell. The side lengths of the two second dielectric layers are different, and two valley photonic crystals are formed by exchanging the side lengths of the two second dielectric layers; Exemplarily, the first dielectric layer is a silicon material, and the second dielectric layer is an air hole, specifically an equilateral triangular air hole. The lattice constant is denoted as a (the side length of the rhombus). By setting the side lengths of the two air holes (denoted as s1 and s2 respectively) to different values and exchanging the side lengths of the two air holes, two valley photonic crystals can be constructed. Exemplarily, the first valley photonic crystal 150 has a first air hole 151 with a small size and a second air hole 152 with a large size. By exchanging the side lengths of the two air holes of the first valley photonic crystal 150 (or by exchanging the positions of the two air holes), the second valley photonic crystal 160 is obtained, as Figure 3 shown; A non-trivial topological bandgap that supports the valley boundary state mode is formed at the boundary between the two valley photonic crystals, and the corresponding values of a, s1, and s2 are set according to the requirements of different working wavelength bands.

[0043] In this embodiment, the method for determining and calculating the working wavelength of the topological photonic waveguide loop 110 is as follows: When s1 = s2 = 0.5a, the unit cell of the valley photonic crystal has C6 symmetry, resulting in a pair of degenerate points in the energy band, and there is no bandgap at this time. When the inversion symmetry (such as s1 = 0.7a, s2 = 0.3a) is broken, the valley photonic crystal structure is reduced to C3 symmetry, resulting in the disappearance of the degenerate points and opening a non-trivial topological bandgap (0.222c / a < f < 0.251c / a) that supports the valley boundary state mode. The relative size of the bandgap can be adjusted by changing the side length difference Δs of the two air holes, and the working frequency of the valley photonic crystal can be adjusted by simple cell scaling. Plotting the extreme values of the two energy bands in Figure 5 results in the region between the two lines being the range of the bandgap.

[0044] In the embodiment of the present invention, the principle of unidirectional light propagation is as follows: Due to the bulk-edge correspondence, the domain wall between the two valley photonic crystals can support a pair of valley-dependent boundary modes with opposite propagation directions. This contrast of the valley edge modes indicates the suppression of the scattering between the two valley edge modes, enabling the light path to propagate unidirectionally only along the domain wall between the two valley photonic crystals. Even if the light source and the first port 101 are not highly accurately aligned, the local oscillator laser can be highly centered and restricted to propagate within the incident light path through this valley-dependent boundary mode. When the incident light path reaches the splitting point 117, due to the symmetry of the first splitting light path 113 and the second splitting light path 114 and the restriction of the valley-dependent boundary mode on the light path (inter-valley scattering suppression), the light path can naturally perform 50 / 50 beam splitting (i.e., 3db power splitting).

[0045] In this embodiment, a topological photonic loop coupler is designed using the boundaries formed by the two valley photonic crystals mentioned above, which can achieve an ideal 3dB splitting. The transmission spectrum simulation results are shown in Figure 2. Figure 6 As shown in Figure 1, the device consists of a harpoon-shaped structure, with four ports formed by connecting two different boundaries. When light is incident from the first port 101, due to the suppression of intervalley scattering, the incident light can only propagate to the third port 103 and the fourth port 104. Due to the mirror symmetry of the coupler, the incident light is evenly output from the third port 103 and the fourth port 104.

[0046] In some embodiments, the first dielectric layer is prepared on a substrate, and a cladding layer is provided around the second dielectric layer.

[0047] In some embodiments, the light source is a continuous wave laser.

[0048] In some embodiments, as Figure 7 As shown, Figure 7 A balanced homodyne detection module 200 is shown connected after a third-stage beam splitter 140, and the balanced homodyne detection module 200 includes: Two photodetectors are connected to the two output ends of the last-stage beam splitter, respectively, to convert the optical signals at the two output ends into electrical signals; a subtractor, connected to the two photodetectors, for subtracting the current signals of the two photodetectors to obtain a differential signal; a transimpedance amplifier for amplifying the differential signal; and Analog-to-digital converter, used to extract the quantum random number sequence generated by vacuum fluctuations.

[0049] The present invention provides a balanced homodyne detection module 200 that matches the above-mentioned light module, which uses two photodiodes with exactly the same performance as two photodetectors to convert the optical signals received from the two output ends of the beam splitter into electrical signals; the two photodiodes are respectively a first photodiode and a second photodiode.

[0050] The output ends of the first photodiode and the second photodiode are connected to the subtractor to obtain a differential signal, which carries the orthogonal amplitude and orthogonal phase information of the vacuum shot noise.

[0051] The subtractor is connected to a transimpedance amplifier to amplify the relatively weak current signal into a voltage signal.

[0052] In yet another embodiment of the present invention, the input end of the analog-to-digital converter is connected to the output end of the transimpedance amplifier to extract a random number sequence based on quantum vacuum fluctuations.

[0053] To further facilitate understanding, the following Figure 1 The workflow and working principle of the vacuum state quantum random entropy source are introduced.

[0054] Workflow Laser light emitted by a continuous-wave laser is input as local oscillator light into the first port 101 of the first-stage beam splitter 120. Vacuum-state signal light is input into the second port 102. After passing through the topological photonic waveguide circuit 110 with a 50 / 50 splitting function, two power-balanced split beams are output from the third port 103 and the fourth port 104. These two power-balanced split beams are split by the two-stage beam splitter to form four channels. Two power-balanced split beams are also output from the two output ports of each third-stage beam splitter 140. Each third-stage beam splitter 140 inputs the two beams into two photodiodes with identical performance, which convert the input optical signals into electrical signals. The two photocurrent signals are subtracted by a subtractor to produce a differential signal. The AC component of the differential signal contains quantum shot noise, which carries the orthogonal amplitude and phase information of the quantum state. The weak current signal is then amplified into a voltage signal through a transimpedance amplifier circuit, and the quantum random number sequence generated by the vacuum fluctuation is extracted through a digital-to-analog converter. The four third-stage beam splitters 140 can obtain four quantum random number sequences.

[0055] How it works The vacuum state is a state of minimum uncertainty. The vacuum field has quantum fluctuations, which lead to uncertainty in the two orthogonal components of the vacuum state. The balanced homodyne detection technology can effectively extract the quantum noise fluctuations of the vacuum state and generate a random number sequence.

[0056] Assume that the annihilation operator of the local oscillator laser is , the corresponding generation operator is ; The annihilation operator of the vacuum state is , the corresponding generation operator is After the topological photonic circuit splits the beam, the generation operators of the two output light paths are: Formula (1) The annihilation operators of the two output light paths are: Formula (2) It is known that the photocurrent is proportional to the number of photons. Assume that the number of photons in the two waveguide circuit signals is and , which is converted into a current signal by the photodiode. The two photocurrent signals are subtracted by the subtractor, and the corresponding photon number difference for: Formula (3) Substituting formula (1) and formula (2) into formula (3), the difference in the number of photons is: Formula (4) Use quantum mechanical operators to express the creation and annihilation operators of the vacuum state: Formula (5) In the above formula, is the vacuum state creation operator, is the annihilation operator of the vacuum state, is the amplitude operator of the vacuum state, is the phase operator of the vacuum state, i is an imaginary unit; The properties of the local oscillator light field are closer to classical physics, and its creation and annihilation operators can be described using complex numbers represented by amplitude and phase: Formula (6) In the above formula, is the phase; The difference in the number of photons is thus obtained: Formula (7) According to formula (7), on the one hand, one or more orthogonal components of the vacuum state can be measured by adjusting the phase of the local oscillator laser, thereby extracting the quantum fluctuation noise of the vacuum state and generating a random number sequence; on the other hand, increasing the power of the local oscillator laser will cause the difference in the number of photons to increase, amplifying the weak vacuum fluctuations and becoming an entropy source for random number extraction.

[0057] Minimum entropy is used to describe the lower limit of uncertainty of a random number sequence and is defined as: Formula (8) in for The value is The probability of using a random number sequence based on minimum entropy post-processing technology can obtain better randomness.

[0058] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit, characterized in that: include: A monolithically integrated light source for providing local oscillator laser; A beam splitter module is composed of a plurality of beam splitters connected in series, each of which includes a first port for inputting a local oscillator laser, a second port for inputting a vacuum laser, and two output ports. The beam splitter is used to split the local oscillator laser inputted at the first port and the vacuum state inputted at the second port into two split laser beams with the same energy and carrying vacuum state signals, which are outputted from the two output ports respectively. The first port of the first-stage beam splitter receives the local oscillator laser emitted by the light source, and the second port of each stage beam splitter inputs the vacuum state. The split laser beams carrying vacuum state signals outputted from the output port of each beam splitter serve as input signals to the first port of the next-stage beam splitter respectively. The balanced homodyne detection module is connected to the two output ends of the last-stage beam splitter and is used to generate quantum random numbers through balanced homodyne detection technology.

2. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 1 is characterized in that: The beam splitter module is composed of 2-10 levels of beam splitters connected in series.

3. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 1 is characterized in that: The beam splitter includes two valley photonic crystals, and the two valley photonic crystals have different topological invariants, thereby forming a topological photonic waveguide circuit with unidirectional optical path propagation at the boundary. The topological photonic waveguide circuit includes a first incident optical path, a second incident optical path, a first split optical path, a second split optical path and two output optical paths. The entrance of the first incident optical path corresponds to the first port, and the entrance of the second incident optical path corresponds to the second port. The first incident optical path and the second incident optical path are linearly coaxial and in opposite directions, so that their exits converge to form a splitting point. The first split optical path and the second split optical path are symmetrically connected at the splitting point with the first incident optical path. The entrances of the two output optical paths are respectively connected to the first split optical path and the second split optical path, and the exits of the two output optical paths correspond to the two output ends respectively.

4. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 3 is characterized in that: The valley photonic crystal is formed by preparing a periodically distributed low refractive index medium layer in a high refractive index medium layer.

5. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 4 is characterized in that: The material of the high refractive index dielectric layer includes silicon, germanium, InP, GaAs, and SiN, and the material of the low refractive index dielectric layer includes air, silicon oxide, organic matter, and photoresist.

6. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 4, characterized in that: The unit cell of the valley photonic crystal is rhombus-shaped. Two low-refractive-index medium holes are opened in the rhombus-shaped unit cell. The areas of the two low-refractive-index medium holes are different. Two types of valley photonic crystals are formed by exchanging the areas of the two low-refractive-index medium holes.

7. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 4, characterized in that: The high refractive index medium layer is prepared on a substrate, and the low refractive index medium holes are prepared in the high refractive index medium layer.

8. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to claim 1, characterized in that: The light source is a continuous wave laser.

9. The vacuum state quantum random entropy source chip based on a large-scale multi-channel topological photonic circuit according to any one of claims 1 to 8, characterized in that: The balanced homodyne detection module includes: Two photodetectors are connected to the two output ends of the last-stage beam splitter, respectively, to convert the optical signals at the two output ends into electrical signals; a subtractor, connected to the two photodetectors, for subtracting the current signals of the two photodetectors to obtain a differential signal; a transimpedance amplifier for amplifying the differential signal; and Analog-to-digital converter, used to extract the quantum random number sequence generated by vacuum fluctuations.

10. A method for generating a multi-channel quantum random number sequence, using the vacuum state quantum random entropy source chip according to any one of claims 1 to 9, characterized in that: The generation method includes the following steps: Start the light source and emit local oscillator laser; The local oscillator laser enters the first port of the first-stage beam splitter and is split 3dB into two split laser beams carrying vacuum state signals by the first-stage beam splitter. The two split laser beams carrying vacuum state signals are split 3dB again by two second-stage beam splitters respectively. The two split laser beams carrying vacuum state signals output from the two output ends of each last-stage beam splitter are both extracted through the corresponding balanced homodyne detection module to extract the quantum random number sequence generated by vacuum fluctuations, forming the generation of multi-channel quantum random number sequences.

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