Magnetic-Field Tuning of Superconducting Qubits for Frequency Collisions

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Solution Overview

Problem

Existing quantum processors face challenges in fabricating qubits with accurate and individually tunable resonance frequencies, leading to issues like frequency crowding, crosstalk, and sensitivity to flux noise, which affect the performance of quantum gates.

Innovation Solution

A superconducting qubit tuning device and method using magnetic fields generated by a superconducting layer and heating elements to adjust qubit resonance frequencies, allowing independent control of each qubit on a chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If qubits are fabricated with fixed resonance frequencies, then manufacturing process is simple, but frequency crowding and crosstalk occur affecting quantum gate performance

Engineering Contradiction:
Improvequbit fabrication simplicityVSAvoidquantum gate performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies dynamics by making the qubit resonance frequency tunable rather than fixed. A magnetic field application mechanism is integrated with each qubit, allowing the resonance frequency to be dynamically adjusted after fabrication. This resolves the contradiction by enabling simple initial fabrication while providing post-fabrication frequency tuning capability to avoid frequency crowding and crosstalk, thereby maintaining quantum gate performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the physical parameter of resonance frequency from a fixed manufacturing-determined value to a可调 parameter controlled by magnetic field strength. By applying different magnetic field strengths to different qubits, each qubit's resonance frequency can be individually tuned to unique values, eliminating frequency collisions while maintaining straightforward fabrication processes.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If qubit resonance frequencies are individually tuned, then frequency collisions are reduced, but device complexity increases

Engineering Contradiction:
Improvequbit frequency tuning accuracyVSAvoidqubit control structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a magnetic field as an intermediary mechanism to tune qubit frequencies. Rather than directly modifying each qubit's physical structure to achieve frequency tuning, a magnetic field serves as a non-invasive mediator that can adjust the effective resonance frequency of superconducting qubits. This approach achieves precise frequency control without requiring complex structural modifications to each qubit.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces potential mechanical or structural tuning mechanisms with a magnetic field control system. Instead of physically adjusting qubit components to change resonance frequencies, the magnetic field provides a contactless, reversible, and precise method for frequency tuning, reducing mechanical complexity while achieving the desired frequency differentiation.

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

3Measurement precision

If magnetic fields are applied to tune qubit frequencies, then frequency precision is improved, but energy consumption increases

Engineering Contradiction:
Improvequbit resonance frequency precisionVSAvoidmagnetic field energy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies magnetic fields selectively and partially - only to the extent necessary to achieve the required frequency separation between qubits. Rather than maintaining maximum magnetic field strength continuously, the system applies just sufficient field strength to tune each qubit to its target frequency, minimizing energy consumption while achieving the precision needed to avoid frequency collisions.

Inventive Principle:
Principle #16Partial or excessive action

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

Enables precise tuning of qubit frequencies, reducing frequency collisions and noise interference, thereby enhancing the performance and coherence of quantum processors.

Implementation Method 1

a first layer configured to generate a magnetic field, the first layer comprising a material exhibiting superconductivity below a critical temperature of the material in a cryogenic temperature range

Methodology Applied
Scientific EffectMagnetic field generation: Electromagnet

Implementation Method 2

a heating element configured to heat a portion of the first layer above the critical temperature

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

A critical temperature of a superconducting material is a temperature at which the material begins to exhibit characteristics of superconductivity. Superconducting materials exhibit very low or zero resistivity to the flow of current.

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 4

Secondly, the material exhibits Meissner effect, i.e., provided they are sufficiently weak, external magnetic fields do not penetrate the superconductor, but remain at its surface.

Methodology Applied
Scientific EffectMeissner effect: Meissner Effect

Data Source

PatentEP3888018B1Qubit tuning by magnetic fields in superconductors
Publication Date: 2025.07.16 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • EP3888018B1 patent drawingFigure 1
  • EP3888018B1 patent drawingFigure 2
  • EP3888018B1 patent drawingFigure 3

AI summary

An embodiment of a qubit tuning device includes a first layer configured to generate a magnetic field, the first layer comprising a material exhibiting superconductivity in a cryogenic temperature range. In an embodiment, the qubit tuning device includes a qubit of a quantum processor chip, wherein the first layer is configured to magnetically interact with the qubit such that a first magnetic flux of the first layer causes a first change in a first resonance frequency of the qubit by a first frequency shift value.