Absorptive Notch Filter for Qubit Readout Pump Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In superconducting quantum computing, the amplification of qubit readout signals using parametric amplifiers often results in unwanted pump leakage, which can degrade the performance of the quantum circuit by introducing noise and interference.
Innovation Solution
The implementation of an absorptive notch filter that suppresses the pump signal by absorbing it rather than reflecting it, thereby reducing gain ripples and maximizing the usable bandwidth of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a common microwave filter is used to reject the pump signal by reflection, then the pump signal is suppressed, but gain ripples are created due to interference between reflected pump signals and the primary pump signal
Solution Approach 1:
Instead of using a reflective filter to suppress the pump signal, the patent inverts the approach by using an absorptive filter that terminates the pump signal. This inversion of the suppression mechanism eliminates the interference between reflected and primary pump signals, thereby removing gain ripples while maintaining pump signal suppression.
Solution Approach 2:
The patent converts the harmful reflected pump signals into beneficial absorbed energy. By using an absorptive filter instead of a reflective one, the previously harmful reflections are transformed into useful signal termination, eliminating the negative interference effects while maintaining the desired pump signal suppression.
2Power
If a parametric amplifier is used to amplify qubit readout signals, then signal amplification is achieved, but pump leakage is introduced which degrades quantum circuit performance
Solution Approach 1:
The patent extracts and removes the harmful pump leakage component from the amplified signal using an absorptive notch filter. This filter specifically targets and absorbs the pump frequency components that leak through the parametric amplifier, separating the desired amplified qubit signal from the unwanted pump leakage.
Solution Approach 2:
The absorptive notch filter acts as an intermediary component between the parametric amplifier and the subsequent circuit stages. It mediates by selectively absorbing pump leakage while allowing the amplified qubit readout signals to pass through, thereby protecting the quantum circuit from pump-induced degradation.
3Ease of operation
If a single frequency range is used for qubit readout, then the system is simple to operate, but the total operating bandwidth is limited
Solution Approach 1:
The patent segments the operating bandwidth into two distinct frequency ranges separated by the pump frequency. The absorptive notch filter creates a notch at the pump frequency, allowing qubit readout signals both above and below the pump frequency to be amplified simultaneously. This segmentation enables dual-band operation while maintaining system simplicity.
Solution Approach 2:
The parametric amplifier system, when combined with the absorptive notch filter, achieves multi-functionality by simultaneously amplifying signals in two separate frequency bands. This universal operation allows the same amplifier to serve multiple qubit readout frequencies without requiring separate amplifier channels, thereby increasing adaptability while maintaining operational simplicity.
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 absorptive notch filter effectively suppresses unwanted pump leakage, reducing noise and interference, and allowing for twice the total operating bandwidth with reduced gain ripples, thus enhancing the performance of the quantum circuit.
Implementation Method 1
an absorptive notch filter that suppresses the pump signal by absorbing it rather than reflecting it
Implementation Method 2
Parametric amplifiers use a mixing process that combines a weak signal with a larger pump signal to produce amplification of the weak signal
Data Source
AI summary
A qubit readout device that suppresses an unwanted pump leakage signal using an absorptive notch filter. The notch filter allows for two distinct ranges of passing frequencies above and below a notch frequency.