Sealed Qubit Vacuum Packaging for Longer Quantum Coherence

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Solution Overview

Problem

Transmon qubits in quantum operation devices are susceptible to decoherence due to adsorbates on their surface, which shorten coherence time, and existing technologies struggle to maintain a clean surface environment.

Innovation Solution

A quantum operation device design featuring a first substrate with a qubit element, a cover that forms a sealed vacuum space around the qubit, and a second substrate that seals the through-holes, preventing adsorbate adsorption and maintaining a clean surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional fabrication processes are used for quantum computing devices, then existing manufacturing capabilities can be utilized, but manufacturing precision and device performance are insufficient

Engineering Contradiction:
Improvemanufacturing precisionVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The fabrication process is divided into multiple lithography stages (first lithography process forming initial pattern, second lithography process forming final pattern), allowing complex quantum computing device structures to be built through sequential simpler steps, thereby achieving high manufacturing precision without requiring a single overly complex fabrication process

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A mandrel structure is formed in advance before the final pattern formation. This preliminary structure serves as a template that guides the subsequent lithography process, enabling precise positioning and pattern transfer while simplifying the overall manufacturing complexity

Inventive Principle:
Principle #10Preliminary action

2Reliability

If quantum computing devices are manufactured with high precision, then device performance improves, but manufacturing complexity and process difficulty increase

Engineering Contradiction:
Improvedevice performanceVSAvoidease of manufacture
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

A mandrel structure is introduced as an intermediary element that simplifies the manufacturing process. The mandrel serves as a temporary template that enables precise pattern formation through standard lithography techniques, thereby achieving high device performance while maintaining ease of manufacture through familiar processes

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mandrel structure acts as a physical template or copy that defines the desired final pattern. By forming features based on this template through lithography, the process achieves high precision using well-established copying techniques rather than requiring complex direct fabrication methods

Inventive Principle:
Principle #26Copying

3Manufacturing precision

If advanced lithography processes are implemented, then manufacturing precision increases, but production time and process complexity increase

Engineering Contradiction:
Improvemanufacturing precisionVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The fabrication is segmented into parallel-capable stages: first lithography for initial patterns, second lithography for final patterns. This segmentation allows each stage to be optimized independently and potentially performed in parallel for different device regions, reducing overall production time while maintaining high precision through specialized processes for each stage

Inventive Principle:
Principle #1Segmentation

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

The design effectively maintains a clean qubit surface, preventing decoherence and extending coherence time by keeping the qubit element in a vacuum state, while allowing for high-density integration and miniaturization.

Implementation Method 1

a first lithography process forming an initial pattern

Methodology Applied
Scientific EffectPhotolithography: Photopolymerisation

Implementation Method 2

a second lithography process forming a final pattern

Methodology Applied
Scientific EffectPhotolithography: Photopolymerisation

Data Source

PatentEP4475176B1Quantum computing device and method for manufacturing quantum computing device
Publication Date: 2026.04.29 FUJITSU LTD
  • EP4475176B1 patent drawingFigure 1
  • EP4475176B1 patent drawingFigure 2
  • EP4475176B1 patent drawingFigure 3

AI summary

A quantum operation device (10) includes: a first substrate (30) that has a through-hole (32A, 32B); a qubit element (20) formed at a first surface (S1) of the substrate (30); a cover (50) that covers a side of the first surface (S1) of the first substrate (30); and a second substrate (40) that is provided on a side of a second surface (S2) opposite to the side of the first surface (S1) of the first substrate (30) and that closes an open end of the through-hole (32A, 32B) on the side of the second surface (S2). A sealed space (51) that surrounds the qubit element (20) and communicates with the through-hole (32A, 32B) is provided between the first surface (S1) and the cover (50).