Quantum Random Number Generation Using Interferometer Merging
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Solution Overview
Problem
The complexity of device configuration in quantum encryption communication systems for generating high-speed, information-theoretically secure random number sequences, particularly when using independent semiconductor laser devices and interferometers, leads to a cumbersome setup.
Innovation Solution
A random number sequence generation apparatus incorporating a semiconductor laser device for pulsed laser beam generation, an interferometer with differently lengthed transmission lines, a light reflecting unit, and an AD converter to produce a binarized random number sequence from interference light, simplifying the configuration while maintaining high-speed generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a random number source capable of generating physical random numbers at high speed (several Gb/s or more) is used, then the generation speed of random number sequence is improved, but the device configuration becomes complicated
Solution Approach 1:
The patent combines the random number generation function with the quantum key distribution system by integrating a random number source into the interferometer configuration. The interferometer itself, with its beam splitters and phase modulators, is used to generate random numbers through quantum interference effects, eliminating the need for separate complex random number generation equipment while achieving high-speed generation of several Gb/s or more.
Solution Approach 2:
The interferometer in the quantum key distribution system is designed to serve dual functions: quantum key distribution and random number generation. By utilizing the existing optical paths, beam splitters, and phase modulation capabilities of the interferometer, the system can generate random numbers as a byproduct of the quantum interference process, thereby achieving multi-functionality without adding significant complexity.
2Reliability
If independent semiconductor laser device and interferometer are used for quantum key distribution, then the reliability of quantum encryption communication is improved, but the device configuration becomes complicated
Solution Approach 1:
The patent integrates the random number source with the interferometer components, combining what would traditionally be separate independent devices into a unified system. The beam splitters, phase modulators, and detection systems of the interferometer are used simultaneously for both quantum key distribution and random number generation, reducing the number of independent components while maintaining security through the fundamental quantum interference effects.
3Ease of operation
If a simple configuration is used for random number generation, then the ease of operation is improved, but the generation speed may be insufficient for high-speed information communication
Solution Approach 1:
The patent replaces traditional electronic random number generation mechanisms with quantum optical interference effects. By using the inherent quantum randomness of photon interference in the interferometer, the system achieves high-speed random number generation without complex electronic control systems, simplifying the overall configuration while maintaining high productivity at several Gb/s or more.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for the generation of information-theoretically secure random number sequences at high speeds with a simplified setup, enhancing the efficiency and reliability of quantum encryption communication systems.
Implementation Method 1
a semiconductor laser device repeatedly generating a pulsed laser beam having a disordered phase for each pulse through pulse oscillation
Implementation Method 2
an interferometer including a first transmission line and a second transmission line that have mutually-different transmission line lengths
Implementation Method 3
a light reflecting unit connected to the second port and inputting the pulsed laser beam output from the second port to the second port again by reflecting the pulsed laser beam
Implementation Method 4
a photodiode connected to the third port, to which interference light of the pulsed laser beam is input, and outputting an electrical signal in accordance with the input of the interference light
Implementation Method 5
an AD converter configured to generate a random number sequence on the basis of a magnitude relationship between a signal intensity of the electrical signal and a threshold set in advance
Data Source
AI summary
A random number sequence generation apparatus includes: a semiconductor laser device repeatedly generating a pulsed laser beam having a disordered phase; an interferometer including a first transmission line and a second transmission line, a first port connected to an input terminal side and to which the pulsed laser beam is input, a second port connected to an output terminal side and outputs the pulsed laser beam, and a third port connected to the input terminal side; a Faraday mirror connected to the second port and reflecting the pulsed laser beam; a photodiode connected to the third port and outputs an electrical signal in accordance with interference light of the pulsed laser beam that is reflected by the Faraday mirror and passes through one of the transmission lines; and an AD converter configured to generate a random number sequence on the basis of the electrical signal and a threshold.