Josephson Junction Hybrid Tuning for Qubit Frequency Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Scaling superconducting quantum processors with a large number of qubits is challenging due to frequency crowding and frequency collisions, as transition frequencies of qubits deviate from design targets due to semiconductor processing variabilities, necessitating precise post-fabrication tuning of qubit frequencies.
Innovation Solution
A hybrid tuning process combining laser tuning and controlled-current tuning is employed to adjust the resistance of Josephson junctions, utilizing laser annealing and controlled tuning currents to achieve precise and wide-ranging frequency adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large number of qubits are scaled in a quantum processor, then the computational capabilities increase, but frequency crowding and frequency collisions occur due to transition frequencies deviating from design targets
Solution Approach 1:
The patent applies parameter changes by systematically adjusting multiple fabrication parameters including oxidation time, oxidation temperature, deposition rate, and deposition temperature to control the tunnel barrier properties of Josephson junctions. This enables precise control of critical current and transition frequencies to avoid frequency collisions while scaling qubit numbers
Solution Approach 2:
The patent implements preliminary action through pre-baking the substrate before oxidation, and performing oxidation before final deposition steps. These preliminary actions prepare the tunnel barrier with controlled properties that prevent frequency deviations before the qubits are fully fabricated, reducing the need for post-fabrication tuning
2Ease of manufacture
If semiconductor processing is used to fabricate Josephson junctions, then manufacturing scalability improves, but processing variabilities cause transition frequencies to deviate from design targets
Solution Approach 1:
The patent implements feedback by measuring the critical current of Josephson junctions after fabrication and using this measurement to adjust subsequent processing parameters. This closed-loop approach compensates for processing variabilities and ensures transition frequencies match design targets despite semiconductor manufacturing tolerances
Solution Approach 2:
The patent applies local quality by creating Josephson junctions with spatially varying oxidation conditions and deposition parameters across different regions of the substrate. This enables different critical current values and frequency characteristics in different areas, allowing compensation for local processing variations while maintaining overall scalability
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 hybrid tuning process enhances precision and range in tuning junction resistances, reducing frequency collisions and improving the fidelity of quantum gate operations in multi-qubit lattices.
Implementation Method 1
performing a laser tuning process to shift the resistance of the Josephson junction of the at least one superconducting quantum bit from the measured resistance toward a target resistance
Implementation Method 2
performing a controlled-current tuning process by applying a controlled tuning current to shift the resistance of the Josephson junction of the at least one superconducting quantum bit to the target resistance
Data Source
AI summary
Techniques are provided for tuning junction resistances of superconducting tunnel junction devices (e.g., Josephson junctions). For example, a method comprises measuring a resistance of a superconducting tunnel junction device, determining a difference between the measured resistance of the superconducting tunnel junction device and a target resistance for the superconducting tunnel junction device, and performing a hybrid tuning process to shift a resistance of the superconducting tunnel junction device from the measured resistance to the target resistance, the hybrid tuning process comprising a laser tuning process and a controlled-current tuning process.