Qubit Filtered Coupling for Fast Gates and Longer Coherence
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Solution Overview
Problem
In quantum computing, there is a trade-off between increasing the quantum gating speed and maintaining coherence time of qubits due to strong coupling with waveguides, which affects the qubit's radiation loss and data retention.
Innovation Solution
A quantum device with a highpass filter having notches in a first frequency band to reduce coupling efficiency in this band and increase it in a second frequency band, allowing for efficient one-qubit and two-qubit gating operations while minimizing radiation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the coupling between the qubit and the waveguide is increased to reduce gating time, then the quantum lifetime of the qubit becomes shorter
Solution Approach 1:
The patent applies local quality by designing the waveguide with different coupling strengths at different locations. Specifically, the waveguide has a first coupling region with stronger coupling to the control qubit and a second coupling region with weaker coupling to the target qubit. This spatial variation in coupling quality allows the control qubit to achieve fast gating while the target qubit maintains longer coherence, resolving the contradiction between gating speed and quantum lifetime.
2Productivity
If the coupling efficiency between the waveguide and the control qubit is increased to speed up gating, then the radiation loss from the control qubit increases and coherence time is shortened
Solution Approach 1:
The waveguide is designed with spatially varying coupling characteristics: strong coupling in the first coupling region for fast control qubit gating, and weak coupling in the second coupling region for reduced radiation loss from the target qubit. This local differentiation of coupling quality enables high productivity without excessive energy loss.
3Adaptability or versatility
If a single waveguide is used for both control qubit and target qubit coupling, then the coupling efficiency cannot be optimized for both qubits simultaneously
Solution Approach 1:
Rather than using separate waveguides for each qubit, the patent implements a single waveguide with locally differentiated coupling properties. The waveguide structure varies along its length to provide strong coupling where needed (control qubit region) and weak coupling where needed (target qubit region), achieving adaptability for both qubits without increasing overall device complexity.
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 solution enables faster quantum gating with improved coherence time by balancing coupling efficiency across different frequency bands, reducing power consumption and maintaining signal quality.
Implementation Method 1
a first qubit that resonates in the first frequency band; and a second qubit that resonates in the second frequency band
Data Source
AI summary
A quantum device includes a filter having a plurality of notches in a first frequency band lower than a second frequency band, a first qubit that resonates in the first frequency band, and a second qubit that resonates in the second frequency band. The first qubit is input with a signal having a frequency at which the first qubit resonates via the filter to control a state of the first qubit when executing a one-qubit gating, and is input with a signal having a frequency at which the second qubit resonates via the filter to control a state of the second qubit according to a quantum state of the first qubit when executing a two-qubit gating.