A true random number generation method based on polarization entangled photon pairs

Abstract

The present application relates to a kind of true random number generation methods based on polarization entangled photon pair, belong to quantum random number generation technical field.For the limitations of existing quantum random number generator in security and reliability, the present application provides high security, high reliability quantum random number source based on polarization entangled photon pair.Technical scheme includes: linearly polarized pump light is generated using semiconductor laser;The light is bidirectionally pumped periodic polarization potassium titanyl phosphate crystal PPKTP in Sagnac loop using dual-wavelength polarization beam splitter DPBS, and degenerate polarization entangled photon pair is generated;After the entangled photon pair is separated using polarization beam splitter PBS, the signal of detector A is used to trigger the coincidence determination of detector B and C, and original quantum random number seed is generated;Finally, the sequence is post-processed using von Neumann method.The present application provides a kind of quantum random number source with high security and high reliability.

Description

Technical Field

[0001] This invention belongs to the field of quantum random number generation technology, and relates to a method for generating true random numbers based on polarization entangled photon pairs. Background Technology

[0002] Random numbers are a crucial resource in cryptography, communications, and scientific simulations. Their randomness and unpredictability directly impact encryption security, computational reliability, and communication confidentiality. Current random number generation techniques are mainly divided into two categories: classical methods and quantum methods. Classical random number generators rely on deterministic algorithms and initial seeds. While they offer advantages such as high efficiency and ease of implementation, the sequences they generate are inherently pseudo-random, exhibiting periodicity, and are susceptible to reverse engineering or computational prediction. Quantum random number generation schemes typically use attenuated laser pulses to simulate single-photon sources. However, this weakly coherent light source cannot completely avoid the generation of multi-photon pulses, which not only reduces random number generation efficiency but also easily introduces security threats such as photon number splitting attacks, thus affecting the overall security of the system.

[0003] Other existing solutions, such as random number generation methods based on vacuum fluctuations or amplified spontaneous emission, while achieving high random number generation rates, still have limitations in terms of security and system reliability. These limitations mainly manifest as follows: the physical source of randomness is not robust enough, making it susceptible to external environmental interference, or theoretically, it cannot completely eliminate potential predictable risks.

[0004] Therefore, there is an urgent need in this field to explore a new quantum random number generation method that can effectively overcome the above-mentioned defects. This method needs to provide higher randomness and unpredictability from a physical mechanism, while also having a higher level of security and system reliability, in order to meet the needs of modern cryptography and high-security applications. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a true random number generation method based on polarization entangled photon pairs, aiming to provide a quantum random number source with both high security and high reliability. The specific implementation steps are as follows: First, a nonlinear crystal is pumped using a continuous laser to generate polarization entangled photon pairs as the physical source of random numbers through its parametric down-conversion process; second, based on the Sagnac interferometer ring structure, a beam splitter is used to separate the frequency degenerate entangled photon pairs; third, the detection results are filtered and statistically analyzed based on coincidence counting logic to extract the original random number sequence; finally, using von Neumann... The von Neumann post-processing method performs bias correction on the sequence and outputs uniformly distributed quantum random numbers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for generating true random numbers based on polarization entangled photon pairs includes the following steps: S1: A continuous pump light is generated using a semiconductor laser with a wavelength of 405nm, and the pump light is modulated into linearly polarized light using a quarter-wave plate and a half-wave plate; S2: The linearly polarized light is split into clockwise and counterclockwise optical paths by a dual-wavelength polarizing beamsplitter (DPBS) to form a Sagnac loop. The clockwise and counterclockwise optical paths simultaneously irradiate a periodically poled potassium titanate phosphate crystal (PPKTP), causing a spontaneous parametric down-conversion process and generating degenerate polarization entangled photon pairs. The light intensity of the entangled photon pairs satisfies the following relationship:

[0007] Among them, symbols Indicates a direct proportional relationship. d The length of the periodically polarized potassium titanium phosphate crystal is given. c At the speed of light, Let be the phase mismatch amount, and the phase mismatch amount satisfies:

[0008] in, For polarization period, For the pump light wave vector, For the signal light wave vector, For the grating wave vector; S3: After the entangled photon pairs are separated by a polarizing beam splitter (PBS), they are coupled into multimode optical fibers through short focal length lenses, wherein the entangled photon pairs contain signal light and idle light; S4: The idle light transmitted through the polarization beam splitter is received by the detector A with a pigtail, and the signal light reflected by the polarization beam splitter is split into two paths by a 50 / 50 beam splitter. S5: Couple the two beams of signal light after beam splitting into detector B and detector C respectively; S6: Using the signal from detector A as a trigger signal, perform coincidence determination to generate an original quantum random number seed; S7: The original quantum random number seed is post-processed using the von Neumann method to generate a quantum random sequence.

[0009] Furthermore, S2 includes the following steps: S21: The linearly polarized light obtained in S1 is incident on the dual-wavelength polarization beam splitter DPBS, which splits the linearly polarized light into a clockwise propagating beam and a counterclockwise propagating beam to form the Sagnac interference ring and realize bidirectional pumping of the periodically polarized potassium titanium phosphate crystal PPKTP. S22: Both the clockwise and counterclockwise propagating light beams satisfy type II phase matching conditions within the periodically polarized potassium titanyl phosphate crystal (PPKTP), and each undergoes the spontaneous parametric down-conversion process. Each pump photon decays into the energy-conserving and orthogonally polarized signal light and the idler light, wherein the spontaneous parametric down-conversion process is expressed as follows:

[0010] in, The vacuum state of the light field. and These are the operators for generating the signal light and the idle light, respectively. , and The frequencies of the pump light, the signal light, and the idle light are respectively. The two-photon wavefunction is the spontaneous parametric downconversion photon pair, and the two-photon wavefunction is expressed as the product of the amplitude spectrum function of the pump light and the phase matching function of the periodically polarized potassium titanyl phosphate crystal PPKTP. S23: By adjusting the optical path, the spontaneous parametric downconversion process of the bidirectional pump generates constructive interference, and the degenerate photon pair in a defined polarization entanglement state is output at the output port of the dual-wavelength polarization beam splitter (DPBS).

[0011] Furthermore, S6 includes the following steps: S61: The coincidence count is obtained by using a coincidence logic unit to measure the coincidence of the output signals of detector A and detector B and the output signals of detector A and detector C respectively, wherein the output of the coincidence logic unit is a standard TTL level signal; S62: Define random bits based on the result of the coincidence count, wherein when detector A and detector B coincide and detector A and detector C do not coincide, the output is recorded as "1", and when the condition that detector A and detector B coincide and detector A and detector C do not coincide is not met, the output is recorded as "0". Generate an original binary random number sequence as the original quantum random number seed according to the definition.

[0012] Furthermore, S7 includes the following steps: S71: Read adjacent bits in the original quantum random number seed in sequence and group the adjacent bits together; S72: Distinguish each group of adjacent bits, wherein if the group is "00" or "11", discard the group, and if the group is "01" or "10", retain the group; S73: Redefine each group of adjacent bits that are retained, wherein when the retained group is “01”, the group is mapped to a new bit “0”, and when the retained group is “10”, the group is mapped to a new bit “1”, thereby generating the quantum random sequence.

[0013] Furthermore, in step S5, an interference filter is installed in front of detectors B and C.

[0014] The beneficial effects of this invention are as follows: (1) This invention uses polarized entangled photon pairs as the physical source of quantum random numbers, overcoming the inherent defects of using attenuated laser pulses to simulate single-photon sources in existing technologies. Attenuated laser pulses cannot completely avoid multi-photon pulses, which may introduce security threats such as photon number separation attacks. This invention ensures higher randomness from a physical mechanism perspective and provides a quantum random number source with a higher level of security.

[0015] (2) This invention uses a Sagnac interference ring structure to generate entangled photon pairs. A dual-wavelength polarization beam splitter (DPBS) is used to split the pump light into clockwise and counterclockwise optical paths, forming a Sagnac loop, thereby realizing bidirectional pumping of periodically polarized potassium titanate phosphate (PPKTP) crystals. By precisely adjusting the optical path, constructive interference is generated during the bidirectional downconversion process, thereby outputting degenerate photon pairs in a defined polarization entangled state at the output port of the DPBS.

[0016] (3) This invention uses a logic based on coincidence counting to extract the original random number seed. When detector A and detector B coincide and detector A and detector C do not coincide, the output is recorded as "1"; when the above conditions are not met, the output is recorded as "0". This definition based on quantum measurement results directly generates the original binary random number sequence.

[0017] (4) In the final step, this invention uses the von Neumann method to post-process the original quantum random number seed to eliminate any possible small biases and correlations in the sequence. Finally, a new quantum random sequence is generated in which the probabilities of bit 0 and bit 1 appearing are theoretically completely equal.

[0018] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a diagram illustrating the basic components of the quantum random number of this invention. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0021] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] Please see Figure 1 The present invention includes the following steps: S1: A continuous pump light is generated using a semiconductor laser with a wavelength of 405nm, and the pump light is modulated into linearly polarized light using a quarter-wave plate and a half-wave plate.

[0024] S2: Linearly polarized light is split into clockwise and counterclockwise optical paths by a dual-wavelength polarizing beamsplitter (DPBS) to form a Sagnac loop. Simultaneously, it irradiates a periodically polarized potassium titanium phosphate crystal (PPKTP), causing a spontaneous parametric down-conversion process that generates degenerate entangled photons whose intensity satisfies the following relationship: (1) Among them, the symbol " "Indicates a direct proportional relationship" For crystal length, At the speed of light, Let the phase mismatch satisfy: (2) in, For polarization period, For the pump light wave vector, For the signal light wave vector, This is the grating wave vector.

[0025] S3: The generated entangled photon pairs (signal light and idle light) are separated by a polarizing beam splitter (PBS) and efficiently coupled into multimode optical fibers through short focal length lenses.

[0026] S4: The idle light transmitted through the PBS is directly received by the detector A with a pigtail. The signal light reflected by the PBS passes through a 50 / 50 beam splitter and is randomly split into two paths.

[0027] S5: Couple the two signal beams after beam splitting into detectors B and C respectively, and install an interference filter in front of each detector.

[0028] S6: Use the signal from detector A as a trigger signal to perform a coincidence determination, thereby generating the original quantum random number seed.

[0029] S7: The original random number sequence is post-processed using the von Neumann method to eliminate possible small biases and correlations, and finally a quantum random sequence is generated.

[0030] S2 includes the following steps: S21: The linearly polarized pump light obtained in S1 is incident on a dual-wavelength polarization beam splitter, which splits it into two beams that propagate clockwise and counterclockwise to form a Sagnac interference ring and realize bidirectional pumping of the periodically polarized potassium titanium phosphate crystal within the ring.

[0031] S22: The bidirectional pump light satisfies the type II phase-matching condition within the periodically polarized potassium titanate phosphate crystal, and each undergoes a spontaneous parametric downconversion process. Each pump photon decays into a pair of energy-conserved, orthogonally polarized signal and idler light. This process can be represented as: (3) in, The vacuum state of the light field. and These are the operators for generating the signal light and the idle light, respectively. , and The frequencies of the pump light, the signal light, and the idle light are respectively. The two-photon wavefunction of the spontaneous parametric downconversion photon pair can be expressed as the amplitude spectral mode function of the pump light. Phase matching function with nonlinear crystals The product of.

[0032] S23: By precisely adjusting the optical path, constructive interference is generated during the bidirectional downconversion process, thereby outputting degenerate photon pairs in a defined polarization entanglement state at a specific output port of the dual-wavelength polarization beam splitter.

[0033] S6 includes the following steps: S61: Using a coincidence logic unit, coincidence measurements are performed on the output signals of detectors A and B, and detectors A and C, respectively, to obtain the coincidence count between them. The output of the coincidence logic unit is a standard TTL level signal, which can be acquired through the parallel port of a computer.

[0034] S62: Define random bits based on the logical result: when detector A matches detector B but does not match detector C, the output is recorded as "1"; when the above conditions are not met, the output is recorded as "0". Generate the original binary random number sequence according to this rule.

[0035] S7 includes the following steps: S71: Read adjacent bits in the original binary random number sequence in sequence and group them together.

[0036] S72: Determine the combination of two bits in each group. If the group is "00" or "11", discard the data. Only retain the combination if it is "01" or "10".

[0037] S73: Redefine each of the retained groups: (1) If the retained combination is “01”, then map it to the new bit “0”.

[0038] (2) If the retained combination is “10”, then map it to the new bit “1”.

[0039] Through the above three steps, a new quantum random number sequence is finally generated, in which the probabilities of bit 0 and bit 1 appearing are theoretically completely equal.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for generating true random numbers based on polarization-entangled photon pairs, characterized in that: Includes the following steps: S1: A continuous pump light is generated using a semiconductor laser with a wavelength of 405nm, and the pump light is modulated into linearly polarized light using a quarter-wave plate and a half-wave plate; S2: The linearly polarized light is split into a clockwise optical path and a counterclockwise optical path by a dual-wavelength polarization beamsplitter (DPBS) to form a Sagnac loop. The clockwise and counterclockwise optical paths simultaneously irradiate a periodically polarized potassium titanium phosphate crystal (PPKTP), causing a spontaneous parametric down-conversion process and generating degenerate polarization entangled photon pairs. The light intensity of the entangled photon pairs satisfies the following relationship: Among them, symbols Indicates a direct proportional relationship. d The length of the periodically polarized potassium titanium oxyphosphate crystal is given. c At the speed of light, Let be the phase mismatch amount, and the phase mismatch amount satisfies: in, For polarization period, For the pump light wave vector, For the signal light wave vector, For the grating wave vector; S3: After being separated by the polarization beam splitter PBS, the entangled photon pairs are coupled into multimode optical fibers through short focal length lenses, wherein the entangled photon pairs contain signal light and idle light; S4: The idle light transmitted through the polarization beam splitter is received by the detector A with a pigtail, and the signal light reflected by the polarization beam splitter is split into two paths by a 50 / 50 beam splitter. S5: Couple the two beams of signal light after beam splitting into detector B and detector C respectively; S6: Using the signal from detector A as a trigger signal, perform coincidence determination to generate an original quantum random number seed; S7: The original quantum random number seed is post-processed using the von Neumann method to generate a quantum random sequence.

2. The true random number generation method based on polarization entangled photon pairs according to claim 1, characterized in that: S2 includes the following steps: S21: The linearly polarized light obtained in S1 is incident on the dual-wavelength polarization beam splitter DPBS, which splits the linearly polarized light into a clockwise propagating beam and a counterclockwise propagating beam to form the Sagnac interference ring and realize bidirectional pumping of the periodically polarized potassium titanium phosphate crystal PPKTP. S22: Both the clockwise and counterclockwise propagating light beams satisfy type II phase matching conditions within the periodically polarized potassium titanyl phosphate crystal (PPKTP), and each undergoes the spontaneous parametric down-conversion process. Each pump photon decays into the energy-conserving and orthogonally polarized signal light and the idler light, wherein the spontaneous parametric down-conversion process is expressed as follows: in, and The frequencies of the signal light and the idle light are respectively. and These are the operators for generating the signal light and the idle light, respectively. The vacuum state of the light field. The two-photon wavefunction is the spontaneous parametric downconversion photon pair, and the two-photon wavefunction is expressed as the product of the amplitude spectrum function of the pump light and the phase matching function of the periodically polarized potassium titanyl phosphate crystal PPKTP. S23: By adjusting the optical path, the spontaneous parametric downconversion process of the bidirectional pump generates constructive interference, and the degenerate photon pair in a defined polarization entanglement state is output at the output port of the dual-wavelength polarization beam splitter (DPBS).

3. The true random number generation method based on polarization entangled photon pairs according to claim 1, characterized in that: S6 includes the following steps: S61: The coincidence count is obtained by using a coincidence logic unit to measure the coincidence of the output signals of detector A and detector B and the output signals of detector A and detector C respectively, wherein the output of the coincidence logic unit is a standard TTL level signal; S62: Define random bits based on the result of the coincidence count, wherein when detector A and detector B coincide and detector A and detector C do not coincide, the output is recorded as "1", and when the condition that detector A and detector B coincide and detector A and detector C do not coincide is not met, the output is recorded as "0". Generate an original binary random number sequence as the original quantum random number seed according to the definition.

4. The true random number generation method based on polarization entangled photon pairs according to claim 1, characterized in that: S7 includes the following steps: S71: Read adjacent bits in the original quantum random number seed in sequence and group the adjacent bits together; S72: Distinguish each group of adjacent bits, wherein if the group is "00" or "11", discard the group, and if the group is "01" or "10", retain the group; S73: Redefine each group of adjacent bits that are retained, wherein when the retained group is "01", the group is mapped to a new bit "0", and when the retained group is "10", the group is mapped to a new bit "1", thereby generating the quantum random sequence.

5. The true random number generation method based on polarization entangled photon pairs according to claim 1, characterized in that: In step S5, an interference filter is installed in front of detectors B and C.

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