Phonon Downconversion Islands for Quasiparticle-Poisoning Suppression

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Solution Overview

Problem

Current quantum error correction in superconducting qubit arrays is hindered by correlated dephasing and relaxation errors due to phonon-mediated quasiparticle poisoning, which are fatal for error correction unless effectively mitigated.

Innovation Solution

The implementation of electroplated phonon downconversion islands on a substrate, formed by mechanically furrowing a phonon downconversion material, to channel deposited energy away from qubit structures, thereby reducing phonon propagation and quasiparticle poisoning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If phonon downconversion material is deposited as a continuous layer on the substrate, then phonon absorption capability is improved, but energy channeling away from qubits deteriorates due to lack of spatial separation

Engineering Contradiction:

Improvephonon absorption capabilityVSAvoidenergy propagation to qubits

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The continuous phonon downconversion material layer is segmented into discrete islands by mechanical furrowing. This segmentation creates spatial separation between the phonon-absorbing material and the qubit structures, allowing the material to absorb phonons while preventing direct energy coupling to qubits. The furrows act as isolation barriers that channel energy away from qubit regions.

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If mechanical furrowing is used to create phonon downconversion islands, then energy channeling away from qubits is improved, but manufacturing complexity increases due to additional processing steps

Engineering Contradiction:

Improveenergy propagation to qubitsVSAvoidfabrication process simplicity

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces complex lithographic patterning and etching processes with simple mechanical furrowing. A diamond-tipped tool or scribe is used to physically groove the substrate through the phonon downconversion material layer, creating islands without requiring cleanroom lithography facilities. This mechanical approach significantly simplifies the manufacturing process while achieving the same energy isolation function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If electroplating is used to deposit phonon downconversion material, then material deposition efficiency is improved, but deposition control precision deteriorates compared to atomic layer deposition

Engineering Contradiction:

Improvematerial deposition rateVSAvoidfilm thickness uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent utilizes electroplating parameters (current density, electrolyte composition, deposition time, temperature) to control the phonon downconversion material deposition. By adjusting these parameters, the process achieves sufficient film uniformity for phonon absorption functionality while maintaining high deposition rates. The mechanical furrowing step subsequently defines precise island boundaries, compensating for any minor variations in electroplated film thickness.

Inventive Principle:

Principle #35Parameter changes

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

This approach achieves nearly two orders of magnitude suppression of phonon-mediated quasiparticle poisoning, enhancing the robustness of quantum error correction by minimizing quasiparticle density and preventing long-distance energy propagation.

Implementation Method 1

electroplated phonon downconversion material... configured to channel deposited energy away from the qubit structure

Methodology Applied

Scientific EffectPhonon downconversion:

Implementation Method 2

the furrows are formed by mechanical furrowing through the electroplated phonon downconversion material

Methodology Applied

Scientific EffectMechanical furrowing:

Implementation Method 3

applying electrical current to a substrate, the substrate having a qubit structure formed thereon or configured for fabrication of a qubit structure thereon, in contact with an electrolyte, the electrolyte comprising a phonon downconversion material precursor, under conditions sufficient to electroplate phonon downconversion material onto the substrate

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS20250380620A1Fabrication of normal conducting or low-gap islands for downconversion of pair-breaking phonons in superconducting quantum circuits

Publication Date: 2025.12.11 SYRACUSE UNIVERSITY

AI summary

Disclosed herein is a quantum processor comprising a substrate, a qubit structure formed on the substrate, an electroplated phonon downconversion material, and furrows through the electroplated phonon downconversion material forming a plurality of electroplated phonon downconversion islands coupled to the substrate configured to channel deposited energy away from the qubit structure. Also disclosed are methods of making and using the same.