CN115061657B - Quantum random number generator chip - Google Patents
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Abstract
A quantum random number generator chip belongs to the technical field of quantum secure communication and comprises an integrated optical chip and an electronics processing module, wherein the integrated optical chip comprises a light source, an unequal arm interferometer and a photoelectric detection module, the unequal arm interferometer comprises a first beam splitter, a second beam splitter and a phase modulator, and the photoelectric detection module comprises a first photoelectric detector and a second photoelectric detector; the electronics processing module comprises an amplifier, a feedback control module, a data acquisition module and a post-processing module. Compared with the prior art, the differential signal is used as the feedback signal by adopting the unequal-arm interferometer and combining the balance detector, so that the phase compensation can be more accurately carried out; and the generation rate and the randomness of the random numbers are improved, and the requirement on the polarization characteristic of the interferometer is reduced. In addition, the light source, the photoelectric detector and the unequal-arm interferometer are mixed and integrated and are integrally packaged with the electronic module, so that the integration level of the chip is greatly improved.
Description
Technical Field
The invention relates to the technical field of quantum secure communication, in particular to a quantum random number generator chip.
Background
In modern society, random numbers are widely used in many fields such as simulation and cryptography. Random numbers can be classified into two broad categories, pseudo random numbers and true random numbers, depending on the principle of generation. Since pseudo-random numbers are generally generated by algorithms, with the increasing threat of quantum computing, the pseudo-random numbers will become predictable, and thus their security cannot be guaranteed. The Quantum Random Number Generator (QRNG) is a novel technology for generating physical true random numbers by using quantum physical intrinsic characteristics, for example, a quantum random number generator based on quantum vacuum state fluctuation, quantum phase fluctuation of laser spontaneous emission and the equivalent quantum optical principle, and the generated random numbers are completely unpredictable, so that the quantum random number generator has true randomness and is also a more and more mature quantum random number generation scheme researched at present. The quantum random number generator built by adopting the discrete optical elements has the advantages of large volume, complex structure, poor stability and high cost, and is difficult to produce in large scale. Therefore, integration of optical devices is a necessary trend.
The random number generator scheme based on laser spontaneous emission phase fluctuation needs to use an unequal arm interferometer to realize time delay interference on a light source, convert the phase fluctuation of the light source into intensity fluctuation and detect the intensity fluctuation through a photoelectric detector. However, the structure of the unequal-arm interferometer is unstable, on one hand, because phase drift exists between the long arm and the short arm, phase compensation is needed to maintain the stability of interference, and on the other hand, the single photoelectric detector monitors the light intensity to perform phase feedback control, so that the influence caused by the light intensity fluctuation of the light source cannot be eliminated; on the other hand, since the interference has a high requirement on the polarization consistency of the two optical signals, the long-arm and short-arm polarization maintaining characteristics of the general interferometer are different, which affects the stability of the interference result. In addition, in the prior art random number generator scheme, the randomness of the random number only comes from one kind of quantum fluctuation, such as the phase fluctuation of laser spontaneous emission or the quantum fluctuation in a vacuum state, and there is no random number generator capable of simultaneously utilizing two kinds of quantum fluctuation.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a quantum random number generator chip.
The technical scheme of the invention is realized as follows:
a quantum random number generator chip comprises an integrated optical chip and an electronic processing module which are connected with each other,
the integrated optical chip comprises a light source, an unequal arm interferometer and a photoelectric detection module, wherein the unequal arm interferometer comprises a first beam splitter, a second beam splitter and a phase modulator, and the photoelectric detection module comprises a first photoelectric detector and a second photoelectric detector;
the electronic processing module comprises an amplifier, a feedback control module, a data acquisition module and a post-processing module;
the light source is used for generating a continuous optical signal containing spontaneous emission phase fluctuation;
the first beam splitter is used for splitting the continuous optical signal into a first signal light and a second signal light;
the phase modulator is used for adjusting the phase of the first signal light to enable the phase difference between the first signal light and the second signal light to be pi/2;
the second beam splitter is used for enabling the same polarization components of the first signal light and the second signal light after phase modulation and time delay to interfere, converting phase fluctuation of a light source into light intensity fluctuation, enabling orthogonal polarization components of the first signal light and the second signal light to interfere with a vacuum state, converting the vacuum fluctuation into the light intensity fluctuation, and generating two paths of interference light signals;
the first photoelectric detector and the second photoelectric detector are respectively used for converting the interference light signals into current signals and outputting differential current signals of two paths of current signals;
the amplifier is used for amplifying the differential current signal and outputting a corresponding voltage signal;
the feedback control module is used for inputting the amplified differential signal and providing feedback control voltage for the phase modulator;
the data acquisition module is used for carrying out analog-to-digital conversion and sampling on the amplified differential signal to generate an initial random bit;
the post-processing module is used for performing randomness extraction on the input initial random bits and outputting the extracted random bits.
Preferably, the optical waveguide structure of the unequal arm interferometer comprises a first directional coupler, a waveguide delay line, a thermo-optic phase modulator and a second directional coupler,
the first directional coupler is used for splitting a continuous optical signal input to an input port of the first directional coupler into first signal light and second signal light;
the waveguide delay line and the thermo-optic phase modulator are respectively used for delaying and phase modulating the first signal light;
the second directional coupler is used for carrying out superposition interference on the first signal light and the second signal light to generate two paths of interference light signals.
Preferably, the optical waveguide structure of the unequal arm interferometer further includes an adjustable polarization rotator for rotating a polarization state of the second signal light.
Preferably, the light source, the unequal arm interferometer and the photodetection module are integrated on the same substrate by hybrid integration technology.
Preferably, the unequal-arm interferometer is an optical waveguide structure, and the material of the optical waveguide structure is one of silicon dioxide, silicon-on-insulator, lithium niobate thin film or III-V semiconductor compound material.
Preferably, the post-processing module is configured to perform randomness extraction on the input initial random bits through a Toeplitz matrix algorithm using fast fourier transform.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a quantum random number generator chip, which can more accurately perform phase compensation by adopting an unequal arm interferometer combined with a balance detector and taking a differential signal as a feedback signal; when the first signal light and the second signal light interfere with each other, the component interference with the same polarization can convert the phase fluctuation of the light source into light intensity fluctuation, the different polarization components respectively interfere with the vacuum state, the vacuum fluctuation can be converted into the light intensity fluctuation, the finally output signal contains two kinds of quantum fluctuation, the generation rate and the randomness of the random number can be improved, and meanwhile, the requirement on the polarization characteristic of the interferometer is lowered. In addition, the light source, the photoelectric detector and the unequal-arm interferometer are mixed and integrated and are integrated with the electronic module for integrated packaging, so that the overall size of the random number generator can be reduced, and the integration level of the chip is greatly improved.
Drawings
FIG. 1 is a schematic block diagram of the architecture of a quantum random number generator chip of the present invention;
FIG. 2 is a functional block diagram of a first embodiment of an unequal-arm interferometer of a quantum random number generator chip of the present invention;
FIG. 3 is a schematic block diagram of a second embodiment of an unequal-arm interferometer for a quantum random number generator chip of the present invention.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
As shown in fig. 1, a quantum random number generator chip, comprising an integrated optical chip 1 and an electronics processing module 2,
the integrated optical chip 1 comprises a light source 1-1, an unequal arm interferometer 1-2 and a photoelectric detection module 1-3, wherein the unequal arm interferometer 1-2 comprises a first beam splitter 1-2-1, a second beam splitter 1-2-2 and a phase modulator 1-2-3, and the photoelectric detection module 1-3 comprises a first photoelectric detector 1-3-1 and a second photoelectric detector 1-3-2; the electronics processing module 2 comprises an amplifier 2-1, a feedback control module 2-2, a data acquisition module 2-3 and a post-processing module 2-4;
the light source 1-1 is connected with an input port of a first beam splitter 1-2-1; one output port of the first beam splitter 1-2-1 is connected with one input port of the second beam splitter 1-2-2 through a long-arm waveguide and a phase modulator 1-2-3; the other output port of the first beam splitter 1-2-1 is connected with the other input port of the second beam splitter 1-2-2 through a short arm waveguide; two output ports of the second beam splitter 1-2-2 are respectively connected with the first photoelectric detector 1-3-1 and the second photoelectric detector 1-3-2; the differential output ports of the first photoelectric detector 1-3-1 and the second photoelectric detector 1-3-2 are connected with the input port of the amplifier 2-1; the output port of the amplifier 2-1 is divided into two paths which are respectively connected with the input ports of the feedback control module 2-2 and the data acquisition module 2-3; the output port of the feedback control module 2-2 is connected with the electric control port of the phase modulator 1-2-3; the output port of the data acquisition module 2-3 is connected with the input port of the post-processing module 2-4;
the light source 1-1 is used for generating a continuous optical signal containing spontaneous radiation phase fluctuation; the first beam splitter 1-2-1 is configured to split the continuous optical signal into a first signal light and a second signal light; the phase modulator 1-2-3 is used for adjusting the phase of the first signal light to enable the phase difference between the first signal light and the second signal light to be pi/2; the second beam splitter 1-2-2 is used for enabling the same polarization components of the first signal light and the second signal light after phase modulation and time delay to interfere, converting the phase fluctuation of the light source 1-1 into light intensity fluctuation, enabling the orthogonal polarization components of the light source 1-1 and the second signal light to interfere with a vacuum state, converting the vacuum fluctuation into the light intensity fluctuation, and generating two paths of interference light signals; the first photoelectric detector 1-3-1 and the second photoelectric detector 1-3-2 are respectively used for converting the interference light signals into current signals and outputting differential current signals of two paths of current signals; the amplifier 2-1 is used for amplifying the differential current signal and outputting a corresponding voltage signal; the feedback control module 2-2 is used for inputting the amplified differential signal and providing feedback control voltage for the phase modulator 1-2-3; the data acquisition module 2-3 is used for performing analog-to-digital conversion and sampling on the amplified differential signal to generate an initial random bit; the post-processing module 2-4 is configured to perform randomness extraction on the input initial random bits through a Toeplitz matrix algorithm based on fast fourier transform, and output the extracted random bits.
The light source 1-1, the unequal-arm interferometer 1-2 and the photoelectric detection module 1-3 are integrated on the same substrate through a hybrid integration technology. The unequal-arm interferometer 1-2 is an optical waveguide structure, and the optical waveguide structure is made of silicon dioxide, silicon on insulator, lithium niobate thin film or III-V group semiconductor compound material.
The specific working principle is as follows:
the light source 1-1 generates continuous light containing spontaneous emission phase noise, and its electric field can be written as
Wherein,
，
，
respectively field strength, frequency and phase of the continuous light.
The continuous light is split into first signal light and second signal light through the first beam splitter 1-2-1, wherein the first signal light is modulated in phase phi by the phase modulator 1-2-3 when passing through a long arm of the unequal arm interferometer 1-2 and then reaches the second beam splitter 1-2-2, and the second signal light directly reaches the second beam splitter 1-2-2 through a short arm of the unequal arm interferometer 1-2. Since the two paths are different, different polarization changes may be generated, and if the polarization direction of the first signal light is taken as the reference X polarization (for example, the horizontal polarization direction), the component thereof in the Y polarization direction perpendicular to the reference X polarization is 0, the polarization state of the second signal light may be decomposed into a first polarization component in the X polarization direction and a second polarization component in the Y polarization direction, which may be respectively expressed as the first polarization component in the X polarization direction and the second polarization component in the Y polarization direction
Wherein alpha is an included angle between the polarization directions of the first signal light and the second signal light, delta is a phase difference between two polarization components of the second signal light, and tau is photon propagation time corresponding to the arm length difference of the unequal-arm interferometer 1-2.
The components of the first signal light and the second signal light in the X polarization direction interfere at the second beam splitter 1-2-2, and then the components of the two output ports of the second beam splitter 1-2-2 in the X polarization direction are respectively
Since the component of the first signal light in the Y polarization direction is 0, the component of the second signal light in the Y polarization direction interferes with the vacuum state, which may be written as EV (t) = EV + δ X (t) + i δ P (t), where EV + δ X (t) is the amplitude component and δ P (t) is the phase component. The components of the two output ports of the second beam splitter 1-2-2 in the Y polarization direction are respectively
Therefore, the interference result of the two output ports of the second beam splitter 1-2-2 is the synthesis of the component in the X polarization direction and the component in the Y polarization direction, and is converted into photocurrents i1 and i2 by the first photodetector 1-3-1 and the second photodetector 1-3-2, respectively, and the output differential current is
Having an average value of
Variance of
It can be seen that the first term of the above equation is the variance of the light source phase fluctuation
The second term is the variance of fluctuation in vacuum state
The obtained result is the superposition of the variance of the two kinds of quantum fluctuation, and the result is finally converted into the change of voltage, and the amplitude is larger than that of single quantum fluctuation.
When the unequal arm interferometer 1-2 has phase drift, the voltage of the phase modulator 1-2-3 needs to be dynamically adjusted for phase compensation. Assuming the phase drift of the unequal arm interferometer 1-2 is ε, the differential current can be written as
Due to the fact that
Randomly varied within a small range, the average value of the differential current being
It can be seen that it is directly related to the amount of phase drift and the compensation by the phase modulators 1-2-3 adjusts the average value of the differential current to 0. Therefore, a voltage signal obtained by amplifying the differential current through the amplifier is used as a feedback control signal of the phase modulator 1-2-3, and the phase drift can be accurately compensated through the feedback control module 2-2 and the PID control algorithm, so that the phase difference between the long arm and the short arm of the unequal-arm interferometer 1-2 is maintained at 2m pi + pi/2, and the chip can stably work.
After the differential current is amplified by the amplifier, the differential current is sampled by the data acquisition modules 2-3 to complete analog-to-digital conversion, and then the original random bit can be obtained. Since the final measured variance also includes the classical electronics noise variance
The original random bits are further processed by a post-processing module 2-4 into a final random number sequence.
Classical electronics noise variance
The method can be directly obtained by turning off the light source 1-1, and the sum of the variance of the phase fluctuation and the variance of the vacuum fluctuation can be obtained by subtracting the measured total variance, so that the proportion of the sum of the two quantum noises is obtained. And calculating to obtain the minimum entropy Hmin by calculating the quantum noise distribution condition, and determining the compression ratio of the postprocessing Toeplitz matrix algorithm.
Inputting the original random sequence with the length of k output by the data acquisition module 2-4 into the post-processing module 2-6, and determining the length of the output random sequence by using the residual Hash theorem
Wherein n is ADC sampling precision, and epsilon is an information theory safety parameter.
And then constructing a j multiplied by k Toeplitz matrix by using j + k-1 bit random number seeds, multiplying the original data by the Toeplitz matrix to obtain an extracted random bit string, and outputting a final quantum random number.
As shown in FIG. 2, the quantum random number generator chip of the first embodiment of the unequal-arm interferometer of the invention:
the optical waveguide structure of the unequal arm interferometer 1-2 comprises a first directional coupler 1-2-4, a waveguide delay line 1-2-5, a thermo-optic phase modulator 1-2-6 and a second directional coupler 1-2-7, wherein one output port of the first directional coupler 1-2-4 is connected with one input port of the second directional coupler 1-2-7 through the waveguide delay line 1-2-5 and the thermo-optic phase modulator 1-2-6, and the other output port of the first directional coupler 1-2-4 is connected with the other input port of the second directional coupler 1-2-7 through a waveguide; the first directional coupler 1-2-4 is used for splitting a continuous optical signal input to an input port thereof into a first signal light and a second signal light; the waveguide delay line 1-2-5 and the thermo-optic phase modulator 1-2-6 are respectively used for delaying and phase modulating first signal light; the second directional coupler 1-2-7 is used for performing superposition interference on the first signal light and the second signal light to generate two paths of interference light signals.
The specific working process of the embodiment comprises the following steps:
the light source 1-1 generates continuous light containing spontaneous emission phase noise in an electric field of
. The continuous light is split into first signal light and second signal light through the first directional coupler 1-2-4, wherein the first signal light is delayed by tau through a waveguide delay line 1-2-5 and a thermo-optic phase modulator 1-2-6 and is modulated by phase phi, then the first signal light reaches the second directional coupler 1-2-7, and the second signal light directly reaches the second directional coupler 1-2-7 through a waveguide. Since the two paths are different, different polarization changes may be generated, and if the polarization direction of the first signal light is taken as the reference X polarization (for example, the horizontal polarization direction), the component thereof in the Y polarization direction perpendicular to the reference X polarization is 0, the polarization state of the second signal light may be decomposed into a first polarization component in the X polarization direction and a second polarization component in the Y polarization direction, which may be respectively expressed as the first polarization component in the X polarization direction and the second polarization component in the Y polarization direction
Wherein α is an included angle between polarization directions of the first signal light and the second signal light, and δ is a phase difference between two polarization components of the second signal light.
The components of the first signal light and the second signal light in the X polarization direction interfere with each other in the second directional coupler 1-2-7, and the components of the two output ports of the second directional coupler 1-2-7 in the X polarization direction are the components respectively
Since the component of the first signal light in the Y polarization direction is 0, the component of the second signal light in the Y polarization direction interferes with the vacuum state, which can be written as EV (t) = EV + δ X (t) + i δ P (t), where EV + δ X (t) is an amplitude component and δ P (t) is a phase component. The components of the two output ports of the second directional coupler 1-2-7 in the Y polarization direction are respectively
Therefore, the interference result of the two output ports of the second directional coupler 1-2-7 is the composition of the component in the X polarization direction and the component in the Y polarization direction, and is converted into photocurrents i1 and i2 by the first photodetector 1-3-1 and the second photodetector 1-3-2, respectively, and the output differential current is
Having an average value of
Variance is
It can be seen that the first term of the above equation is the variance of the light source phase fluctuation
The second term is the variance of fluctuation in vacuum state
The obtained result is the superposition of the variance of the two kinds of quantum fluctuation, and the result is finally converted into the change of voltage, and the amplitude is larger than that of single quantum fluctuation.
When the phase drift of the unequal-arm interferometer 1-2 exists, the voltage of the thermo-optic phase modulator 1-2-6 needs to be dynamically adjusted for phase compensation. Assuming the phase drift of the unequal arm interferometer 1-2 is ε, the differential current can be written as
Due to the fact that
Randomly varied within a small range, the average value of the differential current being
It can be seen that it is directly related to the amount of phase drift, the average of the differential currents is adjusted to 0 by compensation of thermo-optic phase modulators 1-2-6. Therefore, a voltage signal obtained by amplifying the differential current through the amplifier is used as a feedback control signal of the thermo-optic phase modulator 1-2-6, and the phase drift can be accurately compensated through the feedback control module 2-2 and the PID control algorithm, so that the phase difference between the long arm and the short arm of the unequal-arm interferometer 1-2 is maintained at 2m pi + pi/2, and the chip can stably work.
After the differential current is amplified by the amplifier, the differential current is sampled by the data acquisition module 2-3 to complete analog-to-digital conversion, and then the original random bit can be obtained. Since the final measured variance also includes the classical electronics noise variance
The original random bits are further processed by a post-processing module 2-4 into a final random number sequence.
Classical electronics noise variance
The method can be directly obtained by turning off the light source 1-1, and the sum of the variance of the phase fluctuation and the variance of the vacuum fluctuation can be obtained by subtracting the measured total variance, so that the proportion of the sum of the two quantum noises is obtained. And calculating to obtain the minimum entropy Hmin by calculating the quantum noise distribution condition, and determining the compression ratio of the postprocessing Toeplitz matrix algorithm.
Inputting the original random sequence with the length of k output by the data acquisition module 2-4 into the post-processing module 2-6, and determining the length of the output random sequence by using the residual Hash theorem
Wherein n is ADC sampling precision, and epsilon is an information theory safety parameter.
And then constructing a j multiplied by k Toeplitz matrix by using j + k-1 bit random number seeds, multiplying the original data by the Toeplitz matrix to obtain an extracted random bit string, and outputting a final quantum random number.
As shown in fig. 3, the quantum random number generator chip unequal-arm interferometer of the second embodiment of the invention:
the optical waveguide structure of the unequal-arm interferometer 1-2 comprises a first directional coupler 1-2-4, a waveguide delay line 1-2-5, a thermo-optic phase modulator 1-2-6, a second directional coupler 1-2-7 and an adjustable polarization rotator 1-2-8, wherein one output port of the first directional coupler 1-2-4 is connected with one input port of the second directional coupler 1-2-7 through the waveguide delay line 1-2-5 and the optical phase modulator 1-2-6, and the other output port of the first directional coupler 1-2-4 is connected with the other input port of the second directional coupler 1-2-7 through the adjustable polarization rotator 1-2-8; the first directional coupler 1-2-4 is used for splitting a continuous optical signal input to an input port thereof into a first signal light and a second signal light; the waveguide delay line 1-2-5 and the thermo-optic phase modulator 1-2-6 are respectively used for delaying and phase modulating first signal light; the second directional coupler is used for carrying out superposition interference on the first signal light and the second signal light to generate two paths of interference light signals; the adjustable polarization rotator 1-2-8 is used to rotate the polarization state of the second signal light.
The second embodiment comprises the following specific working processes:
the light source 1-1 generates continuous light containing spontaneous emission phase noise in an electric field of
. The continuous light is split into first signal light and second signal light through the first directional coupler 1-2-4, wherein the first signal light is delayed by tau through a waveguide delay line 1-2-5 and a thermo-optic phase modulator 1-2-6 and is modulated by phase phi, and then reaches the second directional coupler 1-2-7, and the second signal light reaches the second directional coupler 1-2-7 through an adjustable polarization rotator 1-2-8. Since the two paths are different, different polarization changes will occur, and if the polarization direction of the first signal light is taken as the reference X polarization (e.g. horizontal polarization direction), it is at the same level as the reference X polarizationThe component in the Y polarization direction perpendicular to the X polarization is 0, and the polarization state of the second signal light can be decomposed into a first polarization component in the X polarization direction and a second polarization component in the Y polarization direction, which can be respectively expressed as
Where α is an included angle between polarization directions of the first signal light and the second signal light, and δ is a phase difference between two polarization components of the second signal light. The adjustable polarization rotator 1-2-8 can realize the dynamic adjustable conversion of any linear polarization state in the waveguide to any linear polarization state, the adjustability utilizes the thermo-optic effect or electro-optic effect of the waveguide, and changes the polarization direction of light in the waveguide by changing the bias voltage of the polarization rotator, namely, the arbitrary adjustment of the included angle alpha of the polarization directions of the first signal light and the second signal light is realized.
The components of the first signal light and the second signal light in the X polarization direction interfere with each other in the second directional coupler 1-2-7, and the components of the two output ports of the second directional coupler 1-2-7 in the X polarization direction are the components respectively
Since the component of the first signal light in the Y polarization direction is 0, the component of the second signal light in the Y polarization direction interferes with the vacuum state, which can be written as EV (t) = EV + δ X (t) + i δ P (t), where EV + δ X (t) is an amplitude component and δ P (t) is a phase component. The components of the two output ports of the second directional coupler 1-2-7 in the Y polarization direction are respectively
Therefore, the interference result of the two output ports of the second directional coupler 1-2-7 is the composition of the component in the X polarization direction and the component in the Y polarization direction, and is converted into photocurrents i1 and i2 by the first photodetector 1-3-1 and the second photodetector 1-3-2, respectively, and the output differential current is
Having an average value of
Variance is
It can be seen that the first term of the above equation is the variance of the light source phase fluctuation
The second term is the variance of fluctuation in vacuum state
That is, the obtained result is the superposition of the variance of two kinds of quantum fluctuation, and the two kinds of fluctuation are finally converted into the change of voltage, and the amplitude is larger than that of single quantum fluctuation. In addition, the air conditioner is provided with a fan,
and
the random number generation rate is optimized by adjusting the proportion of two kinds of quantum fluctuation by adjusting the size of alpha by adjusting the adjustable polarization rotator 1-2-8.
When the unequal arm interferometer 1-2 has phase drift, the voltage of the thermo-optic phase modulator 1-2-6 needs to be dynamically adjusted for phase compensation. Assuming that the phase drift amount of the unequal arm interferometer 1-2 is ε, the differential current can be written as
Due to the fact that
Randomly varied within a small range, the average value of the differential current being
It can be seen that it is directly related to the amount of phase drift, the average of the differential currents is adjusted to 0 by compensation of thermo-optic phase modulators 1-2-6. Therefore, a voltage signal obtained by amplifying the differential current through the amplifier is used as a feedback control signal of the thermo-optic phase modulator 1-2-6, and the phase drift can be accurately compensated through the feedback control module 2-2 in combination with a PID control algorithm, so that the phase difference between the long arm and the short arm of the unequal-arm interferometer 1-2 is maintained at 2m pi + pi/2, and the chip can stably work.
After the differential current is amplified by the amplifier, the differential current is sampled by the data acquisition modules 2-3 to complete analog-to-digital conversion, and then the original random bit can be obtained. Since the final measured variance also includes the classical electronics noise variance
The original random bits are further processed by a post-processing module 2-4 into a final random number sequence.
Classic electronicsVariance of noise
The method can be directly obtained by turning off the light source 1-1, and the sum of the variance of the phase fluctuation and the variance of the vacuum fluctuation can be obtained by subtracting the measured total variance, so that the proportion of the sum of the two quantum noises is obtained. And calculating to obtain the minimum entropy Hmin by calculating the quantum noise distribution condition, and determining the compression ratio of the postprocessing Toeplitz matrix algorithm.
Inputting the original random sequence with the length of k output by the data acquisition module 2-4 into the post-processing module 2-6, and determining the length of the output random sequence by using the residual Hash theorem
Wherein n is ADC sampling precision, and epsilon is an information theory safety parameter.
And then constructing a j multiplied by k Toeplitz matrix by using j + k-1 bit random number seeds, multiplying the original data by the Toeplitz matrix to obtain an extracted random bit string, and outputting a final quantum random number.
According to the embodiments of the invention, the invention provides a quantum random number generator chip, and the differential signal is used as the feedback signal by adopting the unequal arm interferometer and combining the balance detector, so that the phase compensation can be more accurately carried out; when the first signal light and the second signal light interfere with each other, the component interference with the same polarization of the first signal light and the second signal light can convert the phase fluctuation of the light source into light intensity fluctuation, different polarization components respectively interfere with a vacuum state, the vacuum fluctuation can be converted into the light intensity fluctuation, and finally output signals contain two kinds of quantum fluctuation, so that the generation rate and the randomness of random numbers can be improved, and the requirement on the polarization characteristic of the interferometer is reduced. In addition. The light source, the photoelectric detector and the unequal arm interferometer are mixed and integrated and packaged with the electronic module, the overall size of the random number generator can be reduced, and the integration level of the chip is greatly improved.
Claims (6)
1. A quantum random number generator chip, comprising an integrated optical chip (1) and an electronics processing module (2) connected to each other,
the integrated optical chip (1) comprises a light source (1-1), an unequal arm interferometer (1-2) and a photoelectric detection module (1-3), wherein the unequal arm interferometer (1-2) comprises a first beam splitter (1-2-1), a second beam splitter (1-2-2) and a phase modulator (1-2-3), and the photoelectric detection module (1-3) comprises a first photoelectric detector (1-3-1) and a second photoelectric detector (1-3-2);
the electronic processing module (2) comprises an amplifier (2-1), a feedback control module (2-2), a data acquisition module (2-3) and a post-processing module (2-4);
the light source (1-1) is used for generating a continuous optical signal containing spontaneous emission phase fluctuation;
the first beam splitter (1-2-1) is used for splitting the continuous optical signal into a first signal light and a second signal light;
the phase modulator (1-2-3) is used for adjusting the phase of the first signal light to enable the phase difference between the first signal light and the second signal light to be pi/2;
the second beam splitter (1-2-2) is used for enabling the same polarization components of the first signal light and the second signal light which are subjected to phase modulation and time delay to interfere, converting phase fluctuation of the light source (1-1) into light intensity fluctuation, enabling orthogonal polarization components of the light source and the light source to interfere with a vacuum state, converting the vacuum fluctuation into light intensity fluctuation, and generating two paths of interference light signals;
the first photoelectric detector (1-3-1) and the second photoelectric detector (1-3-2) are respectively used for converting the interference optical signals into current signals and outputting differential current signals of two paths of current signals;
the amplifier (2-1) is used for amplifying the differential current signal and outputting a corresponding voltage signal;
the feedback control module (2-2) is used for inputting the amplified differential signal and providing feedback control voltage for the phase modulator (1-2-3);
the data acquisition module (2-3) is used for carrying out analog-to-digital conversion and sampling on the amplified differential signal to generate an initial random bit;
the post-processing module (2-4) is used for performing randomness extraction on the input initial random bits and outputting the extracted random bits.
2. The quantum random number generator chip of claim 1, wherein the optical waveguide structure of the unequal arm interferometer (1-2) comprises a first directional coupler (1-2-4), a waveguide delay line (1-2-5), a thermo-optic phase modulator (1-2-6), and a second directional coupler (1-2-7),
the first directional coupler (1-2-4) is used for splitting a continuous optical signal input to an input port of the first directional coupler into first signal light and second signal light;
the waveguide delay line (1-2-5) and the thermal light phase modulator (1-2-6) are respectively used for delaying and phase modulating first signal light;
the second directional coupler (1-2-7) is used for carrying out superposition interference on the first signal light and the second signal light to generate two paths of interference light signals.
3. The quantum random number generator chip of claim 2, wherein the optical waveguide structure of the unequal arm interferometer (1-2) further comprises an adjustable polarization rotator (1-2-8), the adjustable polarization rotator (1-2-8) for rotating the polarization state of the second signal light.
4. A quantum random number generator chip as claimed in claim 1 or 2 or 3, characterized in that the light source (1-1), the unequal arm interferometer (1-2) and the photodetection module (1-3) are integrated on the same substrate by hybrid integration technology.
5. A quantum random number generator chip as claimed in claim 4, wherein said unequal arm interferometers (1-2) are optical waveguide structures of one of silicon dioxide, silicon on insulator, lithium niobate thin films or III-V semiconductor compound materials.
6. A quantum random number generator chip as claimed in claim 1, characterized in that the post-processing module (2-4) is adapted to perform randomness extraction of the incoming initial random bits by means of Toeplitz matrix algorithm using fast fourier transform.
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| WO2024186266A1 (en) * | 2023-03-07 | 2024-09-12 | National University Of Singapore | Chip-based self-validation quantum random number generator |
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