Variable-Impedance Josephson Amplifier for Wider Qubit Readout Bandwidth
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Solution Overview
Problem
Current Josephson parametric amplifiers have limited applications in multi-qubit quantum circuits due to their narrow band gain, necessitating the development of a wide-band Josephson parametric amplifier.
Innovation Solution
A wide-band Josephson parametric amplifier is designed with a substrate, coplanar waveguide, and nonlinear resonator, featuring varying impedance along its length, achieved through a combination of conductor width adjustments and dielectric bridges, coupled with superconducting quantum interface devices and capacitors, enabling broad bandwidth and tunable amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional Josephson parametric amplifiers are used, then high gain can be achieved, but the bandwidth is narrow
Solution Approach 1:
The coplanar waveguide incorporates a variable impedance section where the conductor width changes along its length, creating a dynamic impedance transformation that expands the amplifier's operational bandwidth while maintaining gain performance
Solution Approach 2:
The patent changes the impedance parameter of the coplanar waveguide by varying the conductor width from 5 micrometers at the input to 15 micrometers at the output, enabling broadband operation through continuous impedance transformation
2Duration of action of moving object
If the conductor width is increased to broaden bandwidth, then the impedance varies, but the manufacturing precision requirements increase
Solution Approach 1:
The coplanar waveguide features local quality variations where the conductor width is specifically increased in the variable impedance section (from 5 to 15 micrometers) while maintaining standard dimensions in other sections, allowing bandwidth expansion without compromising overall manufacturing feasibility
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 provides a wide-bandwidth amplifier with a gain of 15-25 dB, a 500 MHz bandwidth, and noise temperature near the quantum limit, enhancing the performance of multi-qubit quantum processors with state-of-the-art gain and robust nano-fabrication processes.
Implementation Method 1
The coplanar waveguide has an impedance that varies over a length of the coplanar waveguide
Implementation Method 2
one or more superconducting quantum interface devices disposed on the substrate and coupled to the capacitor
Implementation Method 3
wide-band Josephson parametric amplifier
Implementation Method 4
one or more superconducting quantum interface devices disposed on the substrate
Data Source
AI summary
A wide-band Josephson parametric amplifier and method of fabricating the wide-band Josephson parametric amplifier are described. The wide-band Josephson parametric amplifier comprises a substrate, a coplanar waveguide disposed on the substrate having an impedance that varies over a length of the coplanar waveguide, wherein the coplanar waveguide comprises a conductor separated from a first ground plane by a first gap and a second ground plane by a second gap, and a nonlinear resonator disposed on the substrate and coupled to the coplanar waveguide.