Superconducting Qubit Coupling Layout to Prevent Frequency Collisions
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Solution Overview
Problem
Current superconducting quantum computers face challenges with frequency collisions and crosstalk when using Cross-Resonance (CR) to couple qubits, particularly as the number of qubits increases, limiting the ability to establish effective interactions between qubits that are farther apart.
Innovation Solution
A quantum computing device is designed with a combination of qubits having different resonance frequencies and corresponding fixed and tunable frequency buses to enable cross-resonance interactions, using a parametric iSWAP gate to couple qubits, thereby reducing frequency collisions and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cross-Resonance interaction is used to couple qubits, then interaction between qubits is enabled, but frequency collisions and crosstalk occur
Solution Approach 1:
The system segments qubits into two distinct frequency groups (first frequency and second frequency) and uses separate fixed frequency buses for each group. This segmentation prevents frequency collisions by ensuring that qubits at different frequencies interact through dedicated buses, eliminating the crosstalk problem that occurs when all qubits share the same frequency space.
Solution Approach 2:
Fixed frequency buses act as intermediaries between qubit groups. The first fixed frequency bus mediates interactions between qubits at the first frequency, while the second fixed frequency bus mediates interactions between qubits at the second frequency. This intermediary approach allows qubit coupling while preventing direct frequency collisions between different qubit groups.
2Ease of operation
If qubits are closely spaced in frequency for Cross-Resonance, then coupling between qubits is enabled, but frequency collision issues arise
Solution Approach 1:
The patent segments the qubit frequency spectrum into distinct bands (first frequency and second frequency) and assigns qubits to these bands. This segmentation allows qubits within each band to be closely spaced for effective coupling while preventing frequency collisions between bands through the use of separate fixed frequency buses.
Solution Approach 2:
The system changes the frequency parameter of qubits by dividing them into two distinct frequency groups. Qubits in the first group operate at the first frequency, while qubits in the second group operate at the second frequency. This parameter change enables close frequency spacing within groups for coupling while maintaining frequency separation between groups to avoid collisions.
3Productivity
If a large number of qubits are used, then quantum computing capability increases, but frequency collision and crosstalk increase
Solution Approach 1:
The patent segments the large qubit system into multiple frequency groups, each with its own dedicated fixed frequency bus. This segmentation allows the system to scale to hundreds or thousands of qubits while preventing frequency collisions by ensuring that each frequency group operates independently through its own bus infrastructure.
Solution Approach 2:
The patent introduces an additional dimension to the qubit organization by adding frequency grouping beyond simple spatial arrangement. Instead of only organizing qubits by location, the system organizes them by frequency bands, creating a two-dimensional organization (spatial + frequency) that enables scaling while avoiding frequency collisions.
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 configuration allows for stable and efficient interaction between qubits, preventing unwanted cross-resonance interactions and enhancing coherence times, enabling reliable quantum computations even with a large number of qubits.
Implementation Method 1
the first plurality of qubits being configured to interact via cross-resonance through the first fixed frequency bus
Implementation Method 2
a first tunable frequency bus configured to couple at least one of the first plurality of qubits to the second qubit
Data Source
AI summary
A quantum computing device including a first plurality of qubits having a first resonance frequency and a second qubit having a second resonance frequency, the second resonance frequency being different from the first resonance frequency; and a first tunable frequency bus configured to couple the first plurality of qubits to the second qubit.