Stacked Quantum Chip Layout for Low-Loss Qubit Isolation

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Solution Overview

Problem

Deposited dielectrics in quantum circuit elements cause high loss and decoherence, limiting the performance of quantum processors.

Innovation Solution

Arrange circuit elements with lossy dielectrics on the carrier chip's backside, away from qubits, and use low-loss dielectrics and superconducting materials on the frontside to minimize decoherence and energy loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If deposited dielectric materials are used in quantum circuit elements, then device complexity and functionality are improved, but energy loss and decoherence increase

Engineering Contradiction:
Improvedevice complexityVSAvoidenergy loss
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The device is divided into multiple substrates (first substrate, second substrate, third substrate) that are stacked to form enclosures. This segmentation allows the separation of circuit elements with lossy dielectrics from qubits, placing them in different spatial zones within the stacked structure, thereby reducing energy loss while maintaining device functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a planar two-dimensional layout to a three-dimensional stacked architecture. By arranging substrates and circuit elements in vertical layers, the invention creates additional spatial dimensions for isolating lossy components from qubits, enabling reduced energy loss without compromising device complexity or functionality.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If deposited dielectric materials are used in quantum circuit elements, then device functionality is improved, but decoherence increases

Engineering Contradiction:
Improvedevice functionalityVSAvoiddecoherence
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The quantum device is segmented into multiple functional substrates stacked in three dimensions. Lossy dielectric-containing circuit elements are segregated onto specific substrates away from qubits, while qubits reside on separate substrates. This spatial segmentation maintains the versatility of having both lossy and low-loss regions while improving reliability by isolating decoherence sources.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Superconducting layers and vacuum gaps act as intermediary barriers between lossy dielectric circuit elements and qubits. These intermediaries shield the qubits from the harmful effects of deposited dielectrics, allowing the system to maintain both functionality (through inclusion of lossy circuit elements) and reliability (through protection of qubits).

Inventive Principle:
Principle #24Intermediary (Mediator)

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 energy loss and decoherence in quantum circuit elements, enhancing the performance and coherence of quantum processors.

Implementation Method 1

a first layer 105 formed on the first surface 101, in which the first layer 105 comprises circuit elements formed from a layer of superconducting metal that is in direct contact with the underlying substrate 108

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentEP4086965B1Reducing loss in stacked quantum devices
Publication Date: 2025.08.20 GOOGLE LLC
  • EP4086965B1 patent drawingFigure 1
  • EP4086965B1 patent drawingFigure 2
  • EP4086965B1 patent drawingFigure 3

AI summary

The disclosed device (100) includes a first chip (102) comprising a quantum circuit element, particularly a superconducting quantum bit, and a second chip (104) bonded to the first chip. The second chip includes a substrate (108) having first and second opposing surfaces, the first surface (101) facing the first chip including a single layer (105) of superconductor material, and the second surface (103) including a second layer (107), preferably comprising superconductor material layers (113) and including a second circuit element. Preferably, a through connector (109) extends from the first surface to the second surface and electrically connects a portion of the single layer of superconducting material to a second circuit element.