Team Members: Ivan Pinchuk

Supervisors / Mentors: Prof. Nadav Katz, Mr. Or Ben Ishayahou

 

This project explores the development of a three-wave mixing (3WM) traveling-wave  parametric amplifier based on the nonlinear kinetic inductance of tungsten silicide (WSi),  aimed at improving scalability and performance in superconducting qubit readout systems.  Building on the theoretical and experimental framework of prior work, which demonstrated  amplification using NbTiN-based kinetic inductance transmission lines, this design leverages  WSi’s significantly higher nonlinear kinetic inductance to achieve equivalent amplification  with a drastically reduced footprint. Specifically, the proposed architecture reduces the number  of required unit cells from approximately 66,000 to just 6,000–7,000, potentially reducing  overall amplification line length from 33.5 cm to just 6 cm, enabling more compact integration  with cryogenic quantum hardware.

The amplifier utilizes coplanar waveguides (CPW), with

WSi forming the waveguide core and aluminum serving as the interdigitated capacitive elements. To model signal propagation and amplification, the coupled mode equations (CMEs) are solved under phase-matching conditions, and the entire structure is analyzed using ABCD matrix formalism. Simulations of gain and bandwidth across varying pump frequencies and DC bias currents demonstrate comparable performance to the original large-scale design.

The fabrication process comprises two lithographic layers: a WSi base layer defined via optical lithography and wet etching, followed by high-resolution e-beam patterning and wet etching for the aluminum structures.

These results suggest that WSi-based 3WM amplifiers offer  a compelling pathway toward compact, broadband,  quantum-limited amplification suitable for scalable  superconducting quantum systems.