Parallel Josephson Parametric Amplifiers for Smoother Cryogenic Gain
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Solution Overview
Problem
Existing cryogenic amplification devices, particularly Josephson traveling-wave parametric amplifiers (TWPAs), suffer from gain ripples and sensitivity to fabrication imperfections, leading to reflection issues and suboptimal performance in quantum systems.
Innovation Solution
A cryogenic amplification device with multiple parallel Josephson parametric amplifiers, each with a tuned frequency position and phase delay, connected via a power divider to smooth gain curves and reduce ripples, using isolators for unidirectional signal routing and monolithic integration on a chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single Josephson traveling-wave parametric amplifier is used, then high gain is achieved, but gain ripples exceed 5 dB amplitude
Solution Approach 1:
The patent divides the amplification function into multiple parallel Josephson parametric amplifiers (at least two) with different electrical lengths. Each amplifier contributes to the overall gain while having different phase characteristics, which when combined reduce the gain ripples that would otherwise exceed 5 dB in a single amplifier configuration.
Solution Approach 2:
The patent combines the outputs of multiple parallel amplifiers through a combiner. The signals from amplifiers with different electrical lengths are merged in such a way that their phase differences cause the gain ripples to average out, achieving smoother overall gain response while maintaining high amplification.
2Reliability
If waveguide impedance is increased to compensate for high inductance, then 50-ohm matching is achieved, but gain ripples increase due to nonlinearity sensitivity
Solution Approach 1:
Instead of relying on a single waveguide with increased impedance that is highly sensitive to parameter variations, the patent segments the amplification into multiple parallel paths. This segmentation reduces the sensitivity to individual waveguide parameter variations and fabrication imperfections, maintaining impedance matching while reducing gain ripples.
3Object-affected harmful factors
If balanced amplifier network is used to mitigate reflections, then reflection cancellation is achieved, but gain is reduced due to network losses
Solution Approach 1:
The patent uses multiple parallel amplifiers with different electrical lengths to inherently mitigate reflections through phase diversity, avoiding the need for additional balanced network components that would introduce losses and reduce overall gain.
4Manufacturing precision
If multiple parallel amplifiers with different electrical lengths are used, then gain ripples are reduced, but device complexity increases
Solution Approach 1:
The patent integrates multiple amplifiers and their associated components (power dividers, combiners, isolators) into a compact monolithic structure. This nesting approach reduces the overall device footprint and simplifies the physical layout, making the multi-amplifier configuration more manageable despite the increased functional complexity.
Solution Approach 2:
The patent combines multiple functional elements (amplifiers, power dividers, combiners, isolators) into an integrated monolithic device. This merging of components reduces the overall system complexity and improves manufacturability while maintaining the performance benefits of multiple parallel amplifiers with different electrical lengths.
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 achieves higher read-out power, reduced measurement time, and improved frequency range consistency, enabling faster and more precise quantum state read-out with minimal noise and error corrections.
Implementation Method 1
Parametric amplifiers (paramps) utilizing Josephson junctions (JJs) have a rich history dating back to 1967
Implementation Method 2
They exploit a waveguide with a nonlinear element (either Josephson junctions or a high kinetic inductance superconductor) interacting between a strong pump and amplified signal
Implementation Method 3
using isolators for unidirectional signal routing
Implementation Method 4
an input node connected to receive the input signal from the input of the amplification device and configured to divide the input signal into a number of two or more partial signals
Implementation Method 5
an output node connected to receive the amplified partial signals from the parametric amplifiers and configured to combine the received amplified partial signals
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A cryogenic amplification device (1) is according to the invention configured to include at least two parallel parametric amplification lines (7, 8) to thereby enable reduction of gain ripples in the total frequency spectrum of the amplifier bandwidth. (Fig. 1)