Multi-channel quantum random number generator

Abstract

The invention belongs to the technical field of quantum security communication, and discloses a multi-channel quantum random number generator, which comprises a multi-channel spontaneous radiation light source module, a filtering module, a light beam shifter, a photoelectric detection module, a data acquisition module and a data processing module, each path of incident light beam comprises a random phase and a random polarization state of spontaneous radiation; the light beam shifter is used for splitting multiple paths of incident light beams which are vertically incident to a light incident surface of the light beam shifter, so that each path of incident light beam correspondingly generates a path of horizontal polarization component and a path of vertical polarization component which are parallelly emitted from a light emergent surface of the light beam shifter. Compared with the prior art, the non-polarized light with the random phase generated by the spontaneous radiation light source is split into two cross-polarized light beams by the light beam shifter, and a random phase signal is converted into random light intensity fluctuation. The method has high expandability, so that the random number generation rate can be multiplied.

Description

Technical Field

[0001] The present invention relates to the field of quantum secure communication technology, and in particular to a multi-channel quantum random number generator. Background Art

[0002] Random number generators are widely used in applications ranging from business to science, including secure key generation, communications, gaming, and Monte Carlo simulations. Quantum random number generators (QRNGs) exploit truly random quantum mechanical properties such as the superposition of single photons or vacuum fluctuations measured using coherent light. In addition to high-quality random numbers, high generation rates, multi-channel outputs, etc. are also essential for cryptographic applications in optical communications and cloud services.

[0003] Parallel random number generation methods can significantly improve the generation rate and scalability of random numbers by generating multiple random bits simultaneously. Patent CN111488993A proposes a method of generating multiple random entropy sources in parallel by dividing the optical signal generated by the laser into multiple paths and performing balanced detection of vacuum noise on each path. However, this scheme requires expensive narrow linewidth lasers and requires attenuators to be set on half of the optical path, which increases the cost and complexity of the system. The paper Li X, Cohen AB, Murphy TE, et al. S·calable parallel physical random number generator based on a superluminescent LED. Optics letters, 2011, 36(6): 1020-1022. proposes a scheme that uses a photodetector to convert the random phase of a superluminescent diode (SLED) into random light intensity for detection and extraction of random numbers. Multiple optical fiber filters can be cascaded to separate optical signals of multiple wavelengths to achieve the parallel generation of multiple random bits. However, this scheme requires the use of optical fiber devices such as filters, which is not conducive to the miniaturization of QNRG. In addition, each wavelength of light signal is detected by only one photodetector. Since the SLED will produce corresponding changes due to factors such as driving voltage and temperature, the fluctuations in this part will affect the randomness of the random number and cannot be eliminated, reducing the security of the random number. Summary of the invention

[0004] In view of the above defects in the prior art, the present invention proposes a multi-channel quantum random number generator.

[0005] The technical solution of the present invention is achieved in this way: A multi-channel quantum random number generator includes a multi-channel spontaneous radiation light source module, a filter module, a beam deflector, a photoelectric detection module, a data acquisition module and a data processing module. The multi-channel spontaneous radiation light source module is used to generate N parallel incident light beams, each of which contains a random phase and a random polarization state of spontaneous radiation; The filter module is used to perform narrow-band filtering on N incident light beams; A beam deflector is used to split N incident light beams vertically incident on its light incident surface, so that each incident light beam generates a horizontal polarization component and a corresponding vertical polarization component and then emits from its exit surface, and the propagation directions of the two components after emission are consistent; The planes where each horizontal polarization component and the corresponding vertical polarization component are located are perpendicular to the planes where the N incident light beams are located; The photoelectric detection module includes N balanced detection modules, each balanced detection module is used to detect one horizontal polarization component and one corresponding vertical polarization component to generate one differential electrical signal; The data acquisition module includes N analog-to-digital conversion modules, which are used to perform high-speed sampling on N differential electrical signals to generate N initial random bits; The data processing module includes N post-processing modules, which are used to extract randomness from N initial random bits respectively, and generate and output N true random numbers.

[0006] Preferably, the multi-channel spontaneous radiation light source module comprises a broadband superluminescent diode, a first lens L1, a second lens L2 and a mask. L1 and L2 form a lens group for expanding the light beam emitted by the superluminescent diode; The mask plate includes N light-through holes arranged in a straight line and at equal intervals, which are used to allow the expanded light beam to pass through and generate N parallel incident light beams.

[0007] Preferably, the multi-channel spontaneous emission light source module is a 1×N superluminescent diode array, comprising N wide-spectrum superluminescent diode units.

[0008] Preferably, the filter module is a bandpass interference filter with a 3dB line width of 10nm.

[0009] Preferably, the beam shifter is an yttrium vanadate (YVO4) beam shift mirror, and the output parallel beam spacing is not less than 3 mm.

[0010] Preferably, the beam shifter is a calcite beam shifting mirror, and the output parallel beam spacing is not less than 3 mm.

[0011] Preferably, the photoelectric detection module includes 2N photoelectric detectors PD, and every two photoelectric detectors and a corresponding differential circuit constitute a balanced detection module.

[0012] Preferably, the photoelectric detection module is a balanced detector array chip, comprising N balanced detection units, each balanced detector comprising two photodiodes and a corresponding differential circuit.

[0013] Preferably, it further comprises two polarization rotation reflection modules, which are respectively placed in parallel on the light incident surface and the light exit surface of the beam deflector, and the distance between them is adjustable; The polarization rotation reflection module is composed of a quarter wave plate QWP and a reflector M directly bonded together, and the main axis direction of the quarter wave plate is at an angle of 45° to the horizontal polarization direction; The two polarization rotation reflection modules are used to make each vertical polarization component reflect back and forth between the two modules, and emit from its light exit surface after passing through the beam deflector multiple times, so as to increase the delay between each vertical polarization component and the corresponding horizontal polarization component.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a multi-channel quantum random number generator, which uses a beam shifter to split the non-polarized light with random phase generated by a spontaneous radiation light source into two orthogonal polarizations, and detects it through a balanced detector to convert the random phase signal into random light intensity fluctuations. Since the projection intensity of the randomly polarized photons generated by the spontaneous radiation light source is equal on the two orthogonal polarization states, polarization control and light intensity adjustment are not required, and the influence of the light source on the randomness due to factors such as driving signals and temperature can be eliminated. The present invention realizes multi-channel random number output through spatial multiplexing of multi-channel light beams, has a compact structure, and is easy to miniaturize; and has high scalability, so that the random number generation rate can be increased exponentially. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an optical path and principle diagram of a first embodiment of a multi-channel quantum random number generator of the present invention; Figure 2 Schematic diagram of the propagation process of an incident light beam in Embodiment 1 and Embodiment 2 of the present invention; Figure 3 This is the optical path and principle diagram of the second embodiment of the multi-channel quantum random number generator of the present invention; Figure 4 This is a schematic diagram of the propagation process of an incident light beam in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0017] like Figure 1As shown, in the first embodiment of the present invention, A multi-channel quantum random number generator includes a multi-channel spontaneous radiation light source module, a filter module, a beam deflector BD, a photoelectric detection module, a data acquisition module and a data processing module. The multi-channel spontaneous radiation light source module is used to generate N parallel incident light beams, each of which contains a random phase and a random polarization state of spontaneous radiation; The filter module is used to perform narrow-band filtering on N incident light beams; The beam deflector BD is used to split N incident light beams vertically incident on its light incident surface, so that each incident light beam generates a horizontal polarization component and a corresponding vertical polarization component and then emits from its exit surface, and the propagation directions of the two components after emission are consistent; The planes where each horizontal polarization component and the corresponding vertical polarization component are located are perpendicular to the planes where the N incident light beams are located; The photoelectric detection module includes N balanced detection modules, each balanced detection module is used to detect one horizontal polarization component and one corresponding vertical polarization component to generate one differential electrical signal; The data acquisition module includes N analog-to-digital conversion modules, which are used to perform high-speed sampling on N differential electrical signals to generate N initial random bits; The data processing module includes N post-processing modules, which are used to extract randomness from N initial random bits respectively, and generate and output N true random numbers.

[0018] The multi-channel spontaneous radiation light source module includes a wide-spectrum superluminescent diode SLED, a first lens L1, a second lens L2 and a mask. L1 and L2 form a lens group for expanding the light beam emitted by the superluminescent diode SLED; The mask plate includes N light-through holes arranged in a straight line and at equal intervals, which are used to allow the expanded light beam to pass through and generate N parallel incident light beams.

[0019] The filter module is a bandpass interference filter with a 3dB line width of 10nm.

[0020] The beam deflector BD is a calcite beam deflector, and the output parallel beam spacing is not less than 3mm.

[0021] The photoelectric detection module includes 2N photoelectric detectors, and every two photoelectric detectors and corresponding differential circuits constitute a balanced detection module.

[0022] The working principle of the first embodiment is as follows: The superluminescent diode SLED emits a beam with random phase and random polarization state through spontaneous radiation. After the beam is expanded by the lens group composed of L1 and L2, a parallel beam with a longitudinal diameter that can cover N light holes on the mask is formed. The N light holes on the mask are in a straight line and arranged at equal intervals. After the parallel beam passes through the N light holes, N parallel incident beams are generated.

[0023] After being filtered by the bandpass interference filter BPF, N incident light beams are vertically incident on the light incident surface of the beam shifter. Each incident light beam is polarized and split into a horizontal polarization component H and a vertical polarization component V. The process of one incident light beam being polarized and split by the beam shifter and detected by the balanced detector is as follows: Figure 2 shown.

[0024] It can be seen that since the incident light beam is in a random polarization state, after entering the beam shifter, all polarization states are projected into the horizontal polarization and vertical polarization directions, and the intensities of the two are equal, and there is no need for additional polarization control or adjusting the attenuation of one of the paths to make the two equal. Among them, the horizontal polarization component H propagates along the direction of the original light beam, and finally emerges vertically from the light exit surface of the beam shifter; the propagation direction of the vertical polarization component V in the beam shifter has a certain angle with the horizontal polarization component H, and then emerges vertically from the light exit surface of the beam shifter, parallel to the horizontal polarization component V, and the distance D between the two is not less than 3mm. Then the horizontal polarization component H and the vertical polarization component V enter the two photodetectors PD1 and PD2 in the balanced detector BPD for detection, respectively, and differential electrical signals are generated and output.

[0025] The central wavelength λ of the bandpass interference filter BPF is 1550nm, and the 3dB line width is 10nm, then the coherence length of the incident light beam after passing through the bandpass interference filter BPF is , It is much smaller than D=3mm, that is, the process difference between the horizontal polarization component H and the vertical polarization component V is much larger than the coherence time of the incident light beam after filtering. Therefore, the horizontal polarization component H and the vertical polarization component V emitted from the beam shifter at the same time come from two completely independent spontaneous radiation processes, and the differential electrical signals obtained by the two photodetectors PD1 and PD2 are proportional to the light intensity difference between the two.

[0026] The mean and variance of the electrical signal obtained by the photodetector PD1 detecting the vertical polarization component V can be written as , in, is the power spectral density of the incident beam spontaneous emission, are the bandwidths of the bandpass filter and the photodetector respectively. Then the electrical signal output by the photodetector PD1 follows the Gamma distribution , in, The electrical signal obtained by the photodetector PD2 detecting the vertical polarization component H also obeys the same distribution.

[0027] when When , the differential electrical signals of the two photodetectors obey the Gaussian distribution. , in, .

[0028] The Gaussian-distributed differential electrical signals output by the corresponding N balanced detectors BPD are sampled at high speed through N analog-to-digital conversion modules and converted into digital signals to generate N initial random bits. Subsequently, the randomness of the initial random bits is extracted through the corresponding N post-processing modules according to post-processing algorithms, such as global hashing, Toeplitz matrix multiplication, etc., and finally N quantum random numbers with true randomness are output.

[0029] like Figure 3 As shown, the second embodiment of the present invention: The multi-channel spontaneous radiation light source module is a 1×N superluminescent diode array, which includes N wide-spectrum superluminescent diode units.

[0030] The filter module is a bandpass interference filter with a 3dB line width of 10nm.

[0031] The beam shifter is an yttrium vanadate (YVO4) beam shift mirror, and the output parallel beam spacing is not less than 3mm.

[0032] The photoelectric detection module is a balanced detector array chip, which includes N balanced detection units, and each balanced detector BPD includes two photodiodes and a corresponding differential circuit.

[0033] The working principle of the second embodiment is as follows: The 1×N superluminescent diode array emits N parallel incident light beams with random phases and random polarization states through spontaneous radiation. After being filtered by the bandpass interference filter BPF, they are vertically incident on the light incident surface of the beam shifter. Each incident light beam is polarized into a horizontal polarization component H and a vertical polarization component V. One of the incident light beams is polarized and split by the beam shifter and detected by a balanced detection unit of the balanced detector array chip. The corresponding process is as follows: Figure 2 shown.

[0034] It can be seen that since the incident light beam is in a random polarization state, after entering the beam shifter, all polarization states are projected into the horizontal polarization and vertical polarization directions, and the intensities of the two are equal, and there is no need for additional polarization control or adjusting the attenuation of one of the paths to make the two equal. Among them, the horizontal polarization component H propagates along the direction of the original light beam, and finally emerges vertically from the light exit surface of the beam shifter; the propagation direction of the vertical polarization component V in the beam shifter has a certain angle with the horizontal polarization component H, and then emerges vertically from the light exit surface of the beam shifter, parallel to the horizontal polarization component V, and the distance D between the two is not less than 3mm. Then the horizontal polarization component H and the vertical polarization component V enter the two photodiodes PD1 and PD2 in a balanced detection unit for detection, respectively, and differential electrical signals are generated and output.

[0035] The central wavelength λ of the bandpass interference filter BPF is 1550nm, and the 3dB line width is 10nm, then the coherence length of the incident light beam after passing through the bandpass interference filter BPF is , It is much smaller than D=3mm, that is, the process difference between the horizontal polarization component H and the vertical polarization component V is much larger than the coherence time of the incident light beam after filtering. Therefore, the horizontal polarization component H and the vertical polarization component V emitted from the beam shifter at the same time come from two completely independent spontaneous radiation processes, and the differential electrical signals obtained by the two photodiodes PD1 and PD2 are proportional to the light intensity difference between the two.

[0036] The mean and variance of the electrical signal obtained by the photodiode PD1 detecting the vertical polarization component V can be written as , in, is the power spectral density of the incident beam spontaneous emission, are the bandwidths of the bandpass filter and the photodiode respectively. Then the electrical signal output by the photodiode PD1 follows the Gamma distribution , in, The electrical signal obtained by the photodiode PD2 detecting the vertical polarization component H also obeys the same distribution.

[0037] when When , the differential electrical signal of the two photodiodes follows a Gaussian distribution. , in, .

[0038] The Gaussian-distributed differential electrical signals output by the corresponding N balanced detection units are sampled at high speed through N analog-to-digital conversion modules and converted into digital signals to generate N initial random bits. Subsequently, the randomness of the initial random bits is extracted through the corresponding N post-processing modules according to post-processing algorithms, such as global hashing, Toeplitz matrix multiplication, etc., and finally N quantum random numbers with true randomness are output.

[0039] like Figure 4 As shown, the third embodiment of the present invention: It also includes two polarization rotation reflection modules, which are respectively placed in parallel on the light incident surface and the light exit surface of the beam deflector, and the distance between them is adjustable; The polarization rotation reflection module is composed of a quarter wave plate QWP and a reflector M directly bonded together, and the main axis direction of the quarter wave plate is at an angle of 45° to the horizontal polarization direction; The two polarization rotation reflection modules are used to make each vertical polarization component reflect back and forth between the two modules, and emit from its light exit surface after passing through the beam deflector multiple times, so as to increase the delay between each vertical polarization component and the corresponding horizontal polarization component.

[0040] The working principle of the third embodiment is as follows: The working principle is similar to that of the second embodiment, except that the vertical polarization component V does not enter the photodiode for detection directly after it is emitted from the BD for the first time, but first enters a polarization rotation reflection module composed of a quarter wave plate and a reflector directly bonded together, and is reflected by it and the polarization is rotated 90° to become horizontal polarization. After entering the BD for the second time, it is directly transmitted without deviation. This component is then reflected by another polarization rotation reflection module, becomes vertically polarized, and then enters the BD for the third time. The light beam is deflected and emitted perpendicular to the light exit surface of the BD. After the above process is repeated many times, the position where the component is emitted from the light exit surface of the BD gradually moves, that is, the interval between it and the position where the horizontal polarization component H is emitted from the light exit surface of the BD gradually increases, and finally the optical path difference between the two when they reach the corresponding photodiode is greatly increased, thereby meeting the requirement of being much greater than the coherence length.

[0041] It can be seen from the various embodiments of the present invention that the present invention proposes a multi-channel quantum random number generator, which uses a beam shifter to split the non-polarized light with random phase generated by a spontaneous radiation light source into two orthogonal polarizations, and detects it through a balanced detector to convert the random phase signal into random light intensity fluctuations. Since the projection intensity of the randomly polarized photons generated by the spontaneous radiation light source is equal on the two orthogonal polarization states, polarization control and light intensity adjustment are not required, and the influence of the light source on the randomness due to factors such as driving signals and temperature can be eliminated. The present invention realizes multi-channel random number output through spatial multiplexing of multi-channel light beams, has a compact structure, and is easy to miniaturize; and has high scalability, so that the random number generation rate can be increased exponentially.

Claims

1. A multi-channel quantum random number generator, characterized in that: include: A multi-channel spontaneous radiation light source module is used to generate N parallel incident light beams, each of which contains a random phase and a random polarization state of spontaneous radiation; A filtering module, used for performing narrow-band filtering on N incident light beams; A beam deflector is used to split N incident light beams vertically incident on its light incident surface, so that each incident light beam generates a horizontal polarization component and a corresponding vertical polarization component and then emits from its exit surface, and the propagation directions of the two components after emission are consistent; The planes where each horizontal polarization component and the corresponding vertical polarization component are located are perpendicular to the planes where the N incident light beams are located; The photoelectric detection module includes N balanced detection modules, each balanced detection module is used to detect one horizontal polarization component and one corresponding vertical polarization component to generate one differential electrical signal; A data acquisition module, comprising N analog-to-digital conversion modules, for performing high-speed sampling on N differential electrical signals to generate N initial random bits; The data processing module includes N post-processing modules, which are used to extract randomness from N initial random bits respectively, and generate and output N true random numbers.

2. The multi-channel quantum random number generator according to claim 1, characterized in that: The multi-channel spontaneous radiation light source module includes a broadband superluminescent diode, a first lens, a second lens and a mask. The first lens and the second lens constitute a lens group, which is used to expand the light beam emitted by the superluminescent diode; The mask plate includes N light-through holes arranged in a straight line and at equal intervals, which are used to allow the expanded light beam to pass through and generate N parallel incident light beams.

3. The multi-channel quantum random number generator according to claim 1, characterized in that: The multi-channel spontaneous radiation light source module is a 1×N superluminescent diode array, which includes N wide-spectrum superluminescent diode units.

4. The multi-channel quantum random number generator according to claim 1 or 2, characterized in that: The filter module is a bandpass interference filter with a 3dB line width of 10nm.

5. The multi-channel quantum random number generator according to claim 1, characterized in that: The beam deflector is an yttrium vanadate beam deflection mirror, and the output parallel beam spacing is not less than 3mm.

6. The multi-channel quantum random number generator according to claim 1, characterized in that: The beam deflector is a calcite beam deflection mirror, and the output parallel beam spacing is not less than 3mm.

7. The multi-channel quantum random number generator according to claim 1, characterized in that: The photoelectric detection module includes 2N photoelectric detectors, and every two photoelectric detectors and corresponding differential circuits constitute a balanced detection module.

8. The multi-channel quantum random number generator according to claim 1, characterized in that: The photoelectric detection module is a balanced detector array chip, which includes N balanced detection units, and each balanced detector includes two photodiodes and a corresponding differential circuit.

9. The multi-channel quantum random number generator according to claim 1, characterized in that: It also includes two polarization rotation reflection modules, which are respectively placed in parallel on the light incident surface and the light exit surface of the beam deflector, and the distance between them is adjustable; The polarization rotation reflection module is composed of a quarter wave plate and a reflector directly bonded together, and the main axis direction of the quarter wave plate is at an angle of 45° to the horizontal polarization direction; The two polarization rotation reflection modules are used to make each vertical polarization component reflect back and forth between the two modules, and emit from its light exit surface after passing through the beam deflector multiple times, so as to increase the delay between each vertical polarization component and the corresponding horizontal polarization component.

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