Quantum Circuit Layout for Constant-Time Chemistry Simulation

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Solution Overview

Problem

Conventional quantum chemical computations require a large number of gate operations, making them inefficient for simulating complex molecular systems on small quantum computers.

Innovation Solution

The development of a quantum circuit that reduces the complexity of entanglement from O(N) to O(1) by using Hadamard gates, Y-gates, and CNOT gates, along with Jordan-Wigner strings, to efficiently represent and process one and two-body Hamiltonian terms, allowing for parallelization and reduced gate operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional quantum chemical computations are performed using standard circuit models with one and two body Hamiltonian terms, then molecular properties can be computed, but a very large number of gate operations are required

Engineering Contradiction:
Improvecomputation accuracyVSAvoidnumber of gate operations
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The quantum circuit is segmented into distinct functional blocks: basis change gates (Hadamard and Y-gates) that prepare qubit states, CNOT gates that apply entanglement operations, and measurement gates that extract results. This segmentation allows each component to be optimized independently and executed in parallel where possible, reducing the total number of sequential gate operations while maintaining computation accuracy

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the conventional sequential circuit model into a parallel quantum circuit architecture by introducing multiple qubit pathways that can be processed simultaneously. By representing Hamiltonian terms in a transformed basis and applying Jordan-Wigner strings in constant time, the circuit operates in a higher-dimensional quantum state space, enabling parallelization of gate operations that would otherwise be sequential

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If the number of qubits is increased to simulate more complex molecular systems, then computational accuracy improves, but the number of gate operations increases significantly

Engineering Contradiction:
Improvemolecular property computation accuracyVSAvoidcomputation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

Basis change gates (Hadamard and Y-gates) are applied preliminarily to prepare qubits in the appropriate initial states before the main computational operations. This preliminary preparation optimizes the quantum state representation, allowing subsequent CNOT gate operations to execute more efficiently and reducing the total computation time as system complexity increases

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the representation parameters of the Hamiltonian by transforming it into a different basis set and applying Jordan-Wigner strings. This parameter transformation reduces the complexity scaling from O(N) to O(1) for string operations, enabling the circuit to handle larger molecular systems without proportionally increasing gate operations or computation time

Inventive Principle:
Principle #35Parameter changes

3Productivity

If Jordan-Wigner strings are applied in constant time with additional teleportations, then the number of gates is reduced and parallelization is enabled, but circuit complexity increases

Engineering Contradiction:
Improvecomputation efficiencyVSAvoidcircuit structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Ancillary qubits serve as intermediaries that facilitate the application of Jordan-Wigner strings in constant time. These intermediary qubits enable parallelization of entanglement operations by mediating the interaction between computational qubits, allowing multiple operations to execute simultaneously while managing circuit complexity through structured qubit allocation

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3105718B1Improved quantum circuit for chemistry simulation
Publication Date: 2020.05.13 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3105718B1 patent drawingFigure 1A~1B
  • EP3105718B1 patent drawingFigure 1C~1D
  • EP3105718B1 patent drawingFigure 2~3

AI summary

Quantum circuits for chemistry simulation are based on second quantization Hamiltonian coefficients for one-body and two-body interactions. Jordan-Wigner series that conserve parity can be defined so that selected CNOT gates are removed from the associated circuits. Basis change gates such as Hadamard or Y-gates can be coupled to some or all qubits of a quantum circuit or cancelled in view of corresponding gates in adjacent circuits. In some examples, CNOT gates can be moved to different circuit locations.