Multimode Laser Quantum Random Number Generation
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Solution Overview
Problem
Current quantum random number generators (QRNGs) based on quantum phase diffusion in semiconductor lasers require external interferometric elements or multiple laser sources, leading to increased complexity and instability due to the need for precise spectral matching and environmental stability, resulting in a larger form factor and performance issues.
Innovation Solution
A QRNG system that transforms random phases of a multimode laser into random intensity patterns using a fast photodiode, modulating the net gain per round trip from positive to negative values, eliminating the need for external elements by utilizing a multimode laser with proper mode selection and modulation, allowing for compact, integrated designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external interferometric elements or multiple laser sources are used in QRNG, then quantum phase diffusion measurement can be achieved, but device complexity and form factor increase
Solution Approach 1:
The patent merges the functions of multiple laser sources and external interferometric elements into a single integrated semiconductor laser device. The quantum phase diffusion measurement is performed internally within the laser cavity using the laser's own longitudinal modes, eliminating the need for separate interferometers or multiple externally coupled laser sources. This consolidation maintains quantum mechanical entropy properties while significantly reducing device complexity.
Solution Approach 2:
The semiconductor laser serves multiple functions simultaneously: it generates the optical field, provides the longitudinal modes for interference, and acts as the measurement medium for quantum phase diffusion. The laser cavity itself becomes both the source and the measurement apparatus, making the device more universal and self-contained while reducing the total number of required components.
2Reliability
If external interferometric elements or multiple laser sources are used in QRNG, then quantum phase diffusion measurement can be achieved, but overall dimension and footprint increase
Solution Approach 1:
The patent merges the functions of multiple laser sources and external interferometric elements into a single integrated semiconductor laser device. The quantum phase diffusion measurement is performed internally within the laser cavity using the laser's own longitudinal modes, eliminating the need for separate interferometers or multiple externally coupled laser sources. This consolidation maintains quantum mechanical entropy properties while significantly reducing device complexity.
Solution Approach 2:
The measurement function is nested within the laser cavity itself. The quantum phase diffusion measurement is performed using the longitudinal modes that already exist within the laser structure, rather than requiring external measurement apparatus. This nesting approach allows the measurement functionality to be contained within the existing laser footprint, minimizing the overall device area.
3Measurement precision
If multiple laser sources with narrow single mode spectra are used, then spectral matching can be achieved, but intrinsic instability and environmental changes affect performance
Solution Approach 1:
The patent merges the functions of multiple laser sources and external interferometric elements into a single integrated semiconductor laser device. The quantum phase diffusion measurement is performed internally within the laser cavity using the laser's own longitudinal modes, eliminating the need for separate interferometers or multiple externally coupled laser sources. This consolidation maintains quantum mechanical entropy properties while significantly reducing device complexity.
Solution Approach 2:
The patent changes the operating parameters of the semiconductor laser to enable broad spectrum emission that encompasses multiple longitudinal modes. By adjusting the laser to operate in a regime where the spectrum is broad enough to include several modes but still maintains coherent properties, the system achieves both spectral matching and reduced sensitivity to environmental variations. This parameter change allows the laser to be less susceptible to frequency drift and environmental changes compared to narrow single-mode operation.
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
Enables ultrafast and compact quantum random number generation without external interferometric elements, maintaining quantum mechanical entropy properties and reducing correlations between pulses, thus providing stable and efficient random number generation with a smaller footprint.
Implementation Method 1
based on the intrinsic randomness of quantum observables in multimode laser cavities with variable gain or loss
Implementation Method 2
QRNG based on measuring quantum phase diffusion in a pulsed single-mode semiconductor laser
Implementation Method 3
detecting the resulting beating pattern between the longitudinal modes of the laser cavity utilizing a fast photodiode (PIN)
Implementation Method 4
whose net gain per round trip is modulated continuously from positive to negative values and viceversa by means of an electrical pulse driver
Data Source
Figure 1~2b
Figure 3
AI summary
The invention is based on a process and system for producing random numbers by means of a quantum random number generator comprising the steps of operating a multimode laser under the gain-switching mechanism by means of an electrical pulse driver, and detecting the random intensity pattern produced by the inter-mode beating occurring within the laser cavity. The numbers produced are truly random and a minimal number of elements is required for operating the system.