Selective Plasma Tuning of Josephson Junction Resonators
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Solution Overview
Problem
Quantum computing technologies face challenges in maintaining low gate error rates due to frequency collisions and crowding in multi-qubit processors, particularly with fixed-frequency superconducting Josephson-junction-based transmon qubits, where laser annealing offers a limited tuning range for adjusting Josephson junction resistance.
Innovation Solution
The method involves chemically altering Josephson junctions via plasma treatments to modify their electrical resistance, allowing for a wide range of frequency tuning by controlling properties such as processing time, chemical composition, energy delivery, and gas partial pressure, enabling precise adjustment of qubit frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If laser annealing is used to increase Josephson junction resistance, then qubit frequency can be lowered, but the tuning range is limited to 15-20 percent
Solution Approach 1:
The patent changes the physical-chemical state of the Josephson junction by applying plasma treatments that chemically alter the junction resistance. By controlling plasma parameters (power, gas composition, exposure time), the resistance can be tuned across a wide range (0.02-10 ohms), far exceeding the 15-20% range of laser annealing. This directly resolves the contradiction by providing both wide adaptability and precise control through chemical modification rather than thermal annealing.
2Device complexity
If fixed-frequency superconducting qubits are used, then device complexity is reduced, but frequency collisions and crowding occur in multi-qubit processors
Solution Approach 1:
The patent applies local plasma treatments to specific Josephson junctions on the qubit chip, allowing individual or selective tuning of qubit frequencies while maintaining the overall fixed-frequency architecture. This localized approach enables frequency customization for each qubit or junction to avoid collisions and crowding, thereby improving gate fidelity without requiring a complete redesign of the qubit control architecture.
3Adaptability or versatility
If plasma treatment is applied to all Josephson junctions, then frequency tuning is achieved, but selective tuning of individual qubits becomes difficult
Solution Approach 1:
The patent segments the plasma treatment process by using masks or spatially selective plasma sources to treat only specific Josephson junctions or regions of the qubit chip. This allows individual qubits or groups of qubits to be tuned independently while leaving other junctions untouched. The segmentation enables selective frequency tuning without requiring treatment of all junctions, thus maintaining ease of operation while achieving adaptability.
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 effectively mitigates frequency collisions and crowding by providing acute control over qubit frequency tuning, allowing for precise targeting and adjustment of Josephson junction resistances across a large distribution, thereby improving gate fidelity.
Implementation Method 1
chemically altering a Josephson junction of a Josephson junction resonator via a plasma treatment
Implementation Method 2
chemically altering a Josephson junction of a Josephson junction resonator via a plasma treatment
Data Source
AI summary
Techniques regarding selectively tuning the operating frequency of superconducting Josephson junction resonators are provided. For example, one or more embodiments described herein can comprise a method that can include chemically altering a Josephson junction of a Josephson junction resonator via a plasma treatment. The method can also comprise selectively tuning an operating frequency of the Josephson junction resonator based on a property of the plasma treatment.