Antiferromagnetic Quantum Transducer for Low-Interference Qubits

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Solution Overview

Problem

Quantum transducers using ferromagnetic materials in quantum computers are susceptible to magnetic field interference, which can affect qubits.

Innovation Solution

A quantum transducer utilizing an antiferromagnetic insulator with a specific orientation and a microwave transceiver, where laser light is emitted at an angle to minimize magnetic field influence, converting microwave photons into optical photons or vice versa.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ferromagnetic material is used in the quantum transducer, then quantum transduction between microwave photons and optical photons can be achieved, but qubits are affected by the magnetic field generated by the ferromagnetic material

Engineering Contradiction:
Improvequantum transduction functionalityVSAvoidmagnetic field influence on qubits
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the magnetic property parameter of the transducer material from ferromagnetic to antiferromagnetic. This parameter change fundamentally alters the magnetic field characteristics, eliminating the harmful external magnetic field while preserving the quantum transduction functionality through antiferromagnetic resonance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful magnetic field effects into a beneficial configuration by using antiferromagnetic materials where opposing magnetic moments cancel each other out. The magnetic interactions are harnessed for quantum transduction while the net external magnetic field is minimized, protecting qubits from interference.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If laser light is emitted perpendicular to the easy axis of magnetization, then quantum transduction efficiency is maximized, but the magnetic field influence on qubits increases

Engineering Contradiction:
Improvequantum transduction efficiencyVSAvoidmagnetic field influence on qubits
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces asymmetric orientation of the laser beam relative to the easy axis of magnetization. By emitting laser light at an inclined angle rather than perpendicular to the easy axis, the system achieves a balance between maintaining quantum transduction efficiency and reducing magnetic field influence on qubits, breaking the symmetric configuration that caused the contradiction.

Inventive Principle:
Principle #4Asymmetry

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

Reduces the impact of external magnetic fields on quantum devices, enabling efficient quantum transduction with minimal interference, and allows for qubits to operate without significant magnetic field influence.

Implementation Method 1

quantum transduction between microwave photons and optical photons

Methodology Applied
Scientific EffectQuantum transduction:

Implementation Method 2

antiferromagnetic insulator having an easy axis of magnetization

Methodology Applied
Scientific EffectAntiferromagnetism:

Implementation Method 3

Laser light is emitted to the object from a direction inclined with respect to the first axis

Methodology Applied
Scientific EffectLaser emission: Laser

Data Source

PatentEP4693116A1Quantum transducer and quantum transduction method
Publication Date: 2026.02.11 FUJITSU LTD
  • EP4693116A1 patent drawingFigure 1
  • EP4693116A1 patent drawingFigure 2
  • EP4693116A1 patent drawingFigure 3

AI summary

A quantum transducer includes a three-dimensional cavity resonator; an object disposed in the three-dimensional cavity resonator and including an antiferromagnetic insulator having an easy axis of magnetization along a first axis; and a microwave transceiver configured to transmit and receive a microwave to and from the object. Laser light is emitted to the object from a direction inclined with respect to the first axis.