Qubit Pulse Duration Optimization for Quantum Leakage Reduction

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Solution Overview

Problem

Quantum leakage in qubit devices limits the execution of certain quantum algorithms by causing loss of fidelity and decoherence, as existing methods focus on reducing operations rather than addressing leakage into excited states.

Innovation Solution

A method involving measuring energy level values for a multi-level system, determining quantum leakage, and iteratively adjusting pulse durations to minimize leakage, allowing high-fidelity operations without additional error correction schemes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum error correction techniques are used to reduce quantum leakage, then reliability is improved, but device complexity increases due to additional qubits required

Engineering Contradiction:
Improvequantum operation fidelityVSAvoidnumber of qubits
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and addresses quantum leakage directly through iterative pulse optimization, removing the need for additional qubits required by traditional error correction schemes. The method focuses on eliminating the harmful effect (leakage) at its source rather than correcting it afterward with extra components

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The quantum system performs self-optimization through iterative pulse duration adjustment, where each iteration automatically reduces leakage based on measured outcomes. The system serves itself by continuously refining pulse parameters without external intervention or additional error correction infrastructure

Inventive Principle:
Principle #25Self-service

2Productivity

If existing quantum algorithms are optimized by reducing operations and shortening pulse duration, then productivity is improved, but reliability deteriorates due to increased quantum leakage

Engineering Contradiction:
Improvequantum operation speedVSAvoidquantum operation fidelity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where quantum leakage is measured after each pulse operation, and this measurement feeds back into adjusting pulse duration for the next iteration. This closed-loop approach allows the system to maintain high speed while continuously reducing leakage, resolving the trade-off between productivity and reliability

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent makes the pulse duration dynamic rather than fixed, allowing it to be adjusted iteratively based on measured leakage. This dynamic adaptation enables the system to optimize both speed and fidelity by finding the optimal pulse duration that minimizes leakage while maintaining operational efficiency

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3264339B1Quantum leakage
Publication Date: 2021.05.05 HITACHI LTD
  • EP3264339B1 patent drawingFigure 1
  • EP3264339B1 patent drawingFigure 2~3
  • EP3264339B1 patent drawingFigure 4

AI summary

A method of reducing quantum leakage in a qubit device is disclosed. The method comprises receiving a set of energy level values for a multi-level system which includes first and second working levels |o>, |1> which provide a qubit and at least one other level |2> and performing an iteration at least once. the iteration comprising determining quantum leakage from at least one of the first and second working levels to the at least one non-working level for a quantum operation A comprising at least one pulse wherein each pulse has a respective pulse duration, determining whether the quantum leakage is greater than or equal to a threshold value; and, in dependence on the quantum leakage being greater than or equal to the threshold value, changing the duration of at least one of the at least one pulse.