Push-Pull Optical Modulation for Magnetic-Term Ising Computing
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Solution Overview
Problem
Conventional coherent Ising machines are limited to solving only the maximum cut problem due to the absence of a magnetic term in their Hamiltonian, failing to represent combinatorial optimization problems like the four color map or traveling salesman problem.
Innovation Solution
A computing device of the Ising model is configured with a push-pull-type optical modulator to simulate a magnetic term by adjusting its operating point, incorporating a phase sensitive amplifier and optical modulator to generate and measure optical pulses, and a high-speed computation circuit to calculate feedback signals, enabling representation of a general Ising model with both spin-spin and magnetic interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional coherent Ising machine uses a standard push-pull modulator operating at minimum intensity point, then the device complexity is reduced and operation is simplified, but the magnetic term cannot be implemented limiting problem types to only maximum cut problems
Solution Approach 1:
The patent applies preliminary action by pre-shifting the operating point of the push-pull modulator from the minimum intensity point to a non-zero reference level before feedback signal addition. This preliminary adjustment enables the modulator to output light with controllable amplitude signs, which is necessary for implementing the magnetic term in the Ising model Hamiltonian. The operating point shift is performed once at initialization, and then standard feedback control can be applied without requiring continuous complex adjustments.
Solution Approach 2:
The patent changes the operating parameter (reference level) of the push-pull modulator from the conventional minimum intensity point to a non-zero value. This parameter change transforms the modulator's output characteristics, enabling it to produce light amplitudes with controlled signs that correspond to the magnetic field term in the Ising model. This simple parameter adjustment allows the system to solve a broader class of optimization problems including graph coloring and traveling salesman problems.
2Adaptability or versatility
If the operating point of the push-pull modulator is shifted to implement magnetic field term, then various combinatorial optimization problems can be solved, but the modulator control becomes more complex
Solution Approach 1:
The patent performs the operating point shift as a preliminary action during system initialization or problem setup phase. By establishing the appropriate reference level beforehand, the system avoids the need for complex real-time adjustments during problem solving. The preliminary setup enables straightforward feedback signal addition and simplifies the operational procedure for solving different types of combinatorial optimization problems.
Solution Approach 2:
The patent uses the shifted operating point to create a copied or simulated magnetic field effect through the modulator's light amplitude output. Instead of requiring direct magnetic field manipulation, the system copies the magnetic term's effect through optical amplitude modulation, enabling problem representation while maintaining operational simplicity through established feedback control mechanisms.
3Adaptability or versatility
If a conventional coherent Ising machine is used without operating point shift, then the device operation is simple and stable, but it cannot represent problems requiring magnetic field terms such as four color map or traveling salesman problems
Solution Approach 1:
The patent changes the modulator's operating parameter (reference level) to enable accurate representation of spin values with magnetic field influence. By shifting the operating point to a non-zero reference level, the system can accurately encode spin states and their interactions with magnetic fields, thereby achieving precise representation of optimization problems that require magnetic term components in their Hamiltonian formulation.
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 the solution of various combinatorial optimization problems, including the four color map problem, by implementing a local magnetic field term, expanding the range of solvable problems beyond the maximum cut problem.
Implementation Method 1
a phase sensitive amplifier to cause a parametric oscillation at a phase of 0 or π of a plurality of optical pulses
Implementation Method 2
a modulator that modulates, based on the feedback signal calculated by the high-speed computation circuit, the phases and the amplitudes of a plurality of optical pulses
Implementation Method 3
a push-pull modulator that drives two phase modulators provided in both arm waveguides of a Mach-Zehnder interferometer by signals having the same absolute value and different signs so that the driving operation is performed at a point at which light transmitted through the operating point of the modulator has the minimum intensity
Data Source
AI summary
A calculation device of the present disclosure is characterized by implementing an item, which expresses a magnetic field, at each site by adding, to the conventional coherent Ising machine, a function for simulating the magnetic field item. Specifically, light having the amplitude of a predetermined sign is input in the conventional coherent Ising machine by dislocating an operation point of the push-pull-type optical modulator. When the operation point is dislocated to a + direction, DOPO (Degenerate Optical Parametric Oscillator) having the same wavelength as that of DOPO of an optical resonator and having a fixed initial phase difference from pump light into which the light is injected considerably tends to oscillate at 0 phase, and becomes reversed when the operation point is dislocated to a minus direction.