Diffractive Beam Splitting for Qubit Annealing Without Junction Damage
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Solution Overview
Problem
Existing laser annealing techniques for qubits face challenges due to microscale size and design constraints, requiring precise optical path alignment and risking damage to Josephson junctions, especially with semiconductor processing variabilities and liftoff residue.
Innovation Solution
The use of a diffractive beam splitter to split a single optical beam into multiple Gaussian beams, which are projected onto the substrate around the Josephson junction, creating a spatially separated illumination pattern that indirectly heats the junction, minimizing direct irradiation and alignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single optical beam is used for laser annealing, then the alignment precision can be simplified, but the temperature distribution uniformity deteriorates
Solution Approach 1:
The single optical beam is segmented into multiple beams (e.g., four beams) using a diffractive beam splitter. Each beam independently heats a specific region around the Josephson junction, and the combined effect achieves uniform temperature distribution across the junction area, resolving the contradiction between simplicity and uniformity.
2Use of energy by moving object
If the optical beam is directly projected onto the Josephson junction, then the heating efficiency is improved, but the risk of damaging the qubit increases
Solution Approach 1:
The optical beams are strategically positioned to illuminate regions adjacent to the Josephson junction rather than directly on the junction itself. This creates a localized heating pattern where the surrounding area is heated while the sensitive junction region is protected, achieving efficient heating without direct damage risk.
Solution Approach 2:
The substrate and surrounding regions act as intermediary heat transfer media. The optical beams heat these intermediary regions, which then conduct heat to the Josephson junction through thermal conduction, providing indirect heating that maintains heating efficiency while reducing direct damage risk.
3Manufacturing precision
If precise optical path alignment is required, then the laser annealing precision is improved, but the operation complexity and time increase
Solution Approach 1:
The optical beam is split into multiple segments that are distributed around the junction. This segmentation relaxes the alignment requirements compared to a single beam approach, as each segment can be positioned more independently, reducing overall alignment complexity while maintaining annealing precision through the combined effect.
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 method allows for uniform temperature distribution and precise control of the qubit's resonant frequency without damaging the Josephson junction, overcoming alignment challenges and maintaining junction integrity.
Implementation Method 1
generating the Gaussian beams via transmission of a laser generated Gaussian beam through a diffractive optical element
Implementation Method 2
The plurality of optical beams indirectly heat the Josephson junction, resulting in the annealing of the Josephson junction
Data Source
AI summary
Apparatuses and methods are described for laser annealing of a qubit device using a plurality of optical beams. According to an embodiment, a method of tuning a qubit device can comprise generating an optical beam, splitting the optical beam in a plurality of optical beams, and annealing a Josephson junction of the qubit device by projecting the plurality of optical beams onto a region of the qubit device adjacent to the Josephson junction. The disclosed techniques can also be applied for annealing other types of electrical components of various microscale integrated circuit devices.