Adjustable Coupler Circuit for Precise Two-Qubit Gates

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Solution Overview

Problem

Existing methods for implementing two-qubit gates using capacitors result in low precision due to the properties of qubits, leading to insufficient computational accuracy.

Innovation Solution

A method and circuit that utilize an adjustable coupler to activate longitudinal coupling between qubits with a predetermined coupling control signal, minimizing other types of coupling to achieve high-precision two-qubit gates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a capacitor is used to construct a two-qubit gate, then the gate can be implemented, but the precision is low

Engineering Contradiction:

Improveprecision of two-qubit gateVSAvoidcomputational accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the coupling parameters by adjusting the coupling control signal to activate only longitudinal coupling while minimizing other coupling types. This parameter optimization resolves the contradiction by achieving both gate implementation and high precision through controlled coupling conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an adjustable coupler that dynamically controls the coupling between qubits. By making the coupling adjustable rather than fixed, the system can optimize precision while maintaining gate functionality, resolving the contradiction between implementation and accuracy.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If longitudinal coupling is activated between qubits, then the two-qubit gate precision is improved, but other types of coupling may interfere

Engineering Contradiction:

Improveprecision of two-qubit gateVSAvoidother coupling interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and isolates the longitudinal coupling component from other coupling types by using an adjustable coupler with controlled signal activation. This separation allows longitudinal coupling to be optimized for precision while other coupling types are minimized or eliminated, resolving the interference issue.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different coupling characteristics to different aspects of the qubit interaction: longitudinal coupling is activated for precise gate operation, while other coupling types are suppressed. This localized optimization of coupling quality resolves the contradiction between precision improvement and interference reduction.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20260030535A1Method and Circuit for Implementing Two-Qubit Gate

Publication Date: 2026.01.29 ALIBABA DAMO (HANGZHOU) TECH CO LTD

AI summary

Disclosed are a method and a circuit for implementing a two-qubit gate. The method includes: applying a coupling control signal to an adjustable coupler, wherein the adjustable coupler is a coupler between a first data qubit and a second data qubit; and activating, by means of adjusting the coupling control signal, longitudinal coupling between the first data qubit and the second data qubit within a predetermined time, so as to implement the two-qubit gate. The present disclosure solves the technical problem in the related art of low precision of the two-qubit gate.