Josephson Junction Ring Modulator Arrays for Wider JPC Bandwidth
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Solution Overview
Problem
Conventional Josephson parametric converters (JPCs) suffer from limited dynamical bandwidth and dynamic range, making them unsuitable for scalable qubit readout architectures, with current devices having a bandwidth of 10 MHz and a maximum input power of a few photons at 20 dB of gain, which is not sufficient for advanced applications.
Innovation Solution
The integration of arrays of Josephson junctions in a ring modulator configuration with lumped-element capacitors and LC circuits enhances the dynamical bandwidth and dynamic range by increasing the participation ratio and reducing the quality factor of resonators, allowing for a larger dynamic range and smaller footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Josephson ring modulators are used in Josephson parametric converters, then the device can perform three-wave mixing at the quantum limit, but the dynamical bandwidth is limited to 10 MHz and dynamic range is limited to a few photons at 20 dB gain
Solution Approach 1:
The patent divides the single Josephson junction in each arm of the ring modulator into arrays of multiple Josephson junctions (e.g., 4-16 junctions per arm). This segmentation increases the participation ratio of the nonlinear element, thereby enhancing the dynamical bandwidth from 10 MHz to over 100 MHz while maintaining the quantum-limited mixing performance
Solution Approach 2:
The patent transitions from using discrete Josephson junctions to arrays of junctions arranged in a two-dimensional configuration within each arm of the ring modulator. This dimensional change increases the effective area and participation ratio of the nonlinear element, enabling broader bandwidth without proportionally increasing the physical footprint
2Area of stationary object
If conventional Josephson ring modulators with standard resonators are used, then the device achieves quantum-limited amplification, but the footprint is large and dynamic range is insufficient for scalable qubit readout
Solution Approach 1:
The patent merges the functions of the ring modulator and resonators into a more integrated structure where lumped-element capacitors are used to create compact resonant circuits. This combination reduces the overall device footprint while the array configuration maintains or enhances the dynamic range through increased participation ratio
Solution Approach 2:
The patent changes the quality factor parameter of the resonators by using lumped-element capacitors and optimizing the coupling between the array-based ring modulator and resonators. This parameter optimization allows for smaller resonator sizes while maintaining the necessary dynamic range for scalable qubit readout applications
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 enhances the dynamical bandwidth to over 100 MHz and the dynamic range to more than −120 dBm at 20 dB of gain, making Josephson parametric converters more applicable for scalable qubit readout architectures and sensitive quantum measurements.
Implementation Method 1
A Josephson ring modulator (JRM) is a nonlinear dispersive element based on Josephson tunnel junctions that can perform three-wave mixing of microwave signals at the quantum limit
Implementation Method 2
a first and a second resonator formed from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter
Data Source
AI summary
A Josephson parametric converter is provided. The Josephson parametric converter includes a multi-Josephson junction ring modulator having arrays of N Josephson junctions arranged in a ring configuration with nodes inter-dispersed between the arrays. N is an integer having a value greater than one. The Josephson parametric converter further includes a first and a second resonator formed from lumped-element capacitors that shunt the multi-Josephson junction ring modulator and respectively enable a first and a second mode of the Josephson parametric converter. The Josephson parametric converter also includes a first and a second LC circuit for respectively coupling the first and the second resonator to external feedlines.