Analog Quantum Computing for Optimization Problems

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Solution Overview

Problem

Current quantum computing technologies face challenges in maintaining qubit coherence, which is essential for practical implementation of circuit model quantum computers, and are limited by the inability to solve complex computational problems beyond the scope of Universal Turing Machines.

Innovation Solution

A system utilizing superconducting flux qubits with ferromagnetic and controllable couplings to represent variables in Quadratic Unconstrained Binary Optimization problems, where the qubits are interconnected to form a geometric graph, allowing for efficient embedding and solution of optimization problems without requiring long qubit coherence times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If circuit model quantum computers use quantum error correction, then computational reliability is improved, but qubit coherence time requirement increases by 1000 times

Engineering Contradiction:
Improvecomputational reliabilityVSAvoidqubit coherence time
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the circuit model quantum computer architecture with an analog quantum computer architecture. Instead of using discrete quantum gates and circuits that require error correction, the invention uses continuous quantum variables (position and momentum) that naturally evolve according to Hamiltonian dynamics. This substitution eliminates the need for quantum error correction and dramatically reduces coherence time requirements.

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

Solution Approach 2:

The invention changes the fundamental parameters of quantum computation from discrete gate operations to continuous quantum variables. By using position and momentum operators that satisfy canonical commutation relations, the system transforms the computational paradigm from digital quantum computing to analog quantum computing, thereby changing the coherence time requirements.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If Universal Turing Machines are used, then computational universality is maintained, but ability to solve certain computational problems efficiently is limited

Engineering Contradiction:
Improvecomputational universalityVSAvoidcomputational efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent introduces dynamic evolution of quantum states through Hamiltonian dynamics. The system evolves continuously in time according to the Schrödinger equation, allowing complex computational problems to be solved through natural quantum evolution rather than discrete gate sequences. This dynamic approach enables efficient solution of problems like quantum simulation that are intractable for classical computers.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention utilizes periodic quantum evolution through time-dependent Hamiltonians. By controlling the evolution parameters periodically or continuously, the system can implement quantum algorithms that exploit quantum interference and entanglement to achieve exponential speedup for certain computational problems compared to Universal Turing Machines.

Inventive Principle:
Principle #19Periodic action

3Productivity

If qubits are coupled to solve optimization problems, then computational power is increased, but system complexity increases

Engineering Contradiction:
Improvecomputational powerVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a universal analog quantum computer that can solve multiple types of computational problems using the same physical platform. The system uses identical quantum harmonic oscillators for both computation and communication, eliminating the need for separate specialized hardware for different problem types. This multi-functionality reduces overall system complexity while maintaining high computational power.

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

Solution Approach 2:

The invention implements self-organizing quantum systems where the quantum states naturally evolve to represent solutions to optimization problems. The system uses quantum tunneling and energy minimization to automatically find optimal configurations without requiring complex external control mechanisms, thereby reducing system complexity while maintaining computational capability.

Inventive Principle:
Principle #25Self-service

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 approach enables the solution of NP-hard problems like Maximum Independent Set by finding the lowest energy state of the system, providing increased computational power and overcoming noise limitations, thus enhancing the capability to solve complex computational problems efficiently.

Implementation Method 1

Each of the first number of the physical qubit couplers are operated as intra-logical qubit couplers where each of the first number of the physical qubit couplers have a first respective coupling strength that ferromagnetically couples a first respective pair of the physical qubits

Methodology Applied
Scientific EffectFerromagnetic coupling: Ferromagnetism

Implementation Method 2

a second number of the physical qubit couplers are operated as inter-logical qubit couplers, wherein each of the second number of the physical qubit couplers have a second respective coupling strength that controllably couples a second respective pair of the physical qubits

Methodology Applied
Scientific EffectControllable coupling: Magnetic Field

Data Source

PatentUS8190548B2Systems, devices, and methods for analog processing
Publication Date: 2012.05.29 D WAVE SYSTEMS INC
  • US8190548B2 patent drawing
  • US8190548B2 patent drawing
  • US8190548B2 patent drawing

AI summary

A system employs a plurality of physical qubits, each having a respective bias operable to up to six differentiable inputs to solve a Quadratic Unconstrained Binary Optimization problem. Some physical qubit couplers are operated as intra-logical qubit couplers to ferromagnetically couple respective pairs of the physical qubits as a logical qubit, where each logical qubit represents a variable from the Quadratic Unconstrained Binary Optimization problem. The logical qubits may include two or more physical qubits.