Quantum Gate Fractional Fourier-Kravchuk Transform

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Solution Overview

Problem

Current implementations of quantum Fourier-Kravchuk transforms (QKTs) are difficult to scale up and have fixed fractionality, limiting their applicability in signal processing, especially for non-periodic signals, and the computational time is comparable to discrete Fourier transforms (DFTs) without efficient reduction in operations.

Innovation Solution

A method utilizing a single quantum gate with exchange interaction, implemented by a beam splitter, to perform the fractional quantum Fourier-Kravchuk transform on d-level quantum states (qudits), where the interaction is governed by a specific Hamiltonian and the evolution operator generates the transform, allowing for adjustable fractionality and efficient processing of input data sequences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If waveguide-based implementations are used, then quantum Fourier-Kravchuk transform can be realized, but the fractionality is fixed and scaling is difficult

Engineering Contradiction:
Improveadjustable fractionalityVSAvoidscaling difficulty
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces waveguide-based mechanical/optical systems with a quantum gate system governed by a specific Hamiltonian with exchange interaction. This substitution enables adjustable fractionality through the evolution parameter θ while maintaining scalability, as the quantum gate can be implemented with standard quantum computing components rather than fixed waveguide structures.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the controlling parameter from fixed waveguide length to an adjustable evolution parameter θ in the quantum gate. By varying θ, the fractionality α can be continuously adjusted according to α = θ/(2π), providing adaptability without requiring physical restructuring of the system.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If traditional quantum KTs are used, then transform can be performed, but computational time is comparable to DFT without efficient reduction

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidcomputational time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent segments the complex transform operation into a single quantum gate operation governed by a specific Hamiltonian. By encoding the entire fractional quantum Fourier-Kravchuk transform into one gate with evolution parameter θ, the computational complexity is reduced from multiple sequential operations to a single unified operation, achieving constant-time processing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The quantum gate with exchange interaction serves as a universal operator that can perform different fractional transforms by adjusting the evolution parameter θ. This single gate structure can implement any fractionality α = θ/(2π), making it a multi-functional device that eliminates the need for multiple specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If d-level quantum states are used, then higher dimension transformation is enabled, but encoding and detection complexity increases

Engineering Contradiction:
Improvehigher dimension transformationVSAvoidqudit detection
Core Design Contradiction:
Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces an intermediary quantum gate system that mediates between the qudit input states and the measurement apparatus. The quantum gate with exchange interaction transforms the high-dimensional quantum states in a controlled manner, allowing standard quantum detectors to measure the output without directly handling the complexity of high-dimensional state preparation and analysis.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 constant-time information processing for qudit data encoding, reducing computational time significantly and allowing for transformation of large data sequences, which is not possible with waveguide-based implementations, and extends the transform to higher dimensions by using orthogonal spectral or polarization modes independently.

Implementation Method 1

physical systems realizing the Hong-Ou-Mandel (HOM) quantum interference can be used to calculate the quantum fractional Fourier-Kravchuk transform with a single quantum gate

Methodology Applied
Scientific EffectHong-Ou-Mandel quantum interference: Interference

Implementation Method 2

the interaction of two independent modes a and b in the quantum gate is governed by the following Hamiltonian wherein H0 is the free quantum oscillator energy and HI - the interaction Hamiltonian where g corresponds to the exchange interaction strength

Methodology Applied
Scientific EffectExchange interaction:

Implementation Method 3

the quantum gate is implemented by a beam splitter and the input data are encoded as superposition of multiphoton Fock states that interfere on the beam splitter

Methodology Applied
Scientific EffectBeam splitter interference: Interference

Data Source

PatentEP3818477B1A method of performing quantum fourier-kravchuk transform (QKT) and a device configured to implement said method
Publication Date: 2024.10.30 UNIWERSYTET WARSZAWSKI
  • EP3818477B1 patent drawingFigure 1
  • EP3818477B1 patent drawingFigure 2
  • EP3818477B1 patent drawingFigure 3a~3f

AI summary

The present invention relates to a method of performing a fractional quantum Fourier-Kravchuk transform (QKT), characterised in that input data sequence is encoded in quantum amplitudes of a d-level (qudit) state which is processed by a quantum gate implementing an exchange interaction, and the result is read out by means of quantum detectors located behind this device,The invention relates also to a device, in particular a quantum computer, configured to implement said method.