Quantum Qubit Lattice Coupling for NP-Hard Analog Computing

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Solution Overview

Problem

Current analog and digital computing methods face limitations in solving complex problems efficiently, particularly NP-hard problems, due to precision issues in analog systems and the finite state machine approach in digital computers, which restricts the complexity of problems that can be solved and requires significant computational time for large-scale instances.

Innovation Solution

A computational system comprising a lattice of quantum devices with nearest-neighbor and next-nearest neighbor coupling, where each device is a superconducting qubit, enabling the solution of NP class problems by approximating the ground state of systems like the Ising Spin Glass model, thereby overcoming precision and scalability limitations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If analog systems use physical quantities to represent continuous variables, then operations are performed in parallel and faster than digital computers, but precision is limited by the precision to which the continuous variable can be quantified

Engineering Contradiction:
Improvecomputation speedVSAvoidprecision
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent transitions from classical analog parameters (continuous physical quantities) to quantum parameters (discrete quantum states with continuous superposition coefficients). By changing the fundamental parameter representation from classical continuous variables to quantum state vectors, the system achieves both high-speed parallel evolution and high precision through the mathematical properties of quantum mechanics.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the classical mechanical/physical analog system with a quantum mechanical system. Instead of using physical quantities like voltage or pressure to represent variables, the system uses quantum states of quantum devices, where the state vector coefficients provide both the parallel evolution capability and the precision needed to overcome classical analog limitations.

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

2Adaptability or versatility

If digital computers use a finite state machine approach with clocks, then they can solve a broad array of general-purpose computational problems, but the complexity of problems that can be solved is fundamentally limited and significant computational time is required for large-scale instances

Engineering Contradiction:
Improveproblem-solving capabilityVSAvoidcomputational time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent replaces the static, clock-synchronized finite state machine approach with a dynamic quantum system that evolves continuously according to the Schrödinger equation. The quantum system naturally adapts its evolution based on the problem Hamiltonian, allowing it to solve a broad class of problems (including NP-hard problems) without being constrained by clock cycles or fixed state transitions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the fundamental computational model from discrete state transitions to continuous quantum evolution. By using quantum superposition and entanglement, the system can represent and manipulate exponentially more states simultaneously, reducing computational time for complex problems while maintaining versatility through programmable Hamiltonians.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If analog systems are used to solve specific problems, then operations are performed in parallel, but the number of operations is limited by the degree to which the circuits/devices can be duplicated

Engineering Contradiction:
Improvenumber of operationsVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent creates a universal quantum processor that can solve multiple different problems using the same physical hardware. By programming different Hamiltonians and initial states, the same quantum device can address various optimization problems, simulation problems, and other computational tasks, overcoming the limitation of dedicated analog systems while maintaining parallel processing capabilities.

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

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 allows for the efficient solution of NP class problems, such as Maximum Independent Set and Ising Spin Glass, by leveraging quantum properties to find the ground state, reducing computational time and overcoming precision limitations of traditional methods.

Implementation Method 1

each quantum device is a superconducting qubit

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

comprising loops of superconducting material interrupted by Josephson junction(s)

Methodology Applied
Scientific EffectJosephson effect: Josephson Effect

Data Source

PatentUS8008942B2Analog processor comprising quantum devices
Publication Date: 2011.08.30 D WAVE SYSTEMS INC
  • US8008942B2 patent drawing
  • US8008942B2 patent drawing
  • US8008942B2 patent drawing

AI summary

Analog processors for solving various computational problems are provided. Such analog processors comprise a plurality of quantum devices, arranged in a lattice, together with a plurality of coupling devices. The analog processors further comprise bias control systems each configured to apply a local effective bias on a corresponding quantum device. A set of coupling devices in the plurality of coupling devices is configured to couple nearest-neighbor quantum devices in the lattice. Another set of coupling devices is configured to couple next-nearest neighbor quantum devices. The analog processors further comprise a plurality of coupling control systems each configured to tune the coupling value of a corresponding coupling device in the plurality of coupling devices to a coupling. Such quantum processors further comprise a set of readout devices each configured to measure the information from a corresponding quantum device in the plurality of quantum devices.