Josephson Traveling-Wave Parametric Amplifier with Inverse Kerr Phase Matching

TL;DR

This paper demonstrates an inverse Kerr phase matching technique in a superconducting TWPA, achieving high gain, broad bandwidth, minimal gain ripple, and near quantum-limited noise performance, addressing key challenges in quantum computing readout.

Contribution

The paper introduces and experimentally validates the inverse Kerr phase matching method, improving phase matching and gain performance in TWPAs compared to conventional dispersion engineering.

Findings

Achieved 20 dB gain over 3 GHz bandwidth

Demonstrated tunable bandwidth of 8 GHz

Near quantum-limited noise with 1.5 photons added

Abstract

Superconducting traveling-wave parametric amplifiers (TWPA) have emerged as highly versatile devices, offering broadband amplification with quantum-limited noise performance. They hold significant potential for addressing the readout bottleneck in prototype quantum computers, enabling scalability. Key challenges with this technology include achieving sufficient gain with minimal gain ripple while maintaining low noise performance. Efficient phase matching between a weak signal and a strong pump over the entire length of the TWPA is critical to overcoming these challenges. We present an experimental demonstration of the inverse Kerr phase matching technique in a TWPA, first proposed in Ref. Phys. Rev. Appl. 4, 024014. This method addresses several limitations of conventional dispersion engineering approaches of phase matching in the four-wave mixing parametric process in TWPAs. Most notably the existence of an unusable region of gain near the pump frequency which typically corresponds to the region of most optimal phase matching and maximum gain. The inverse Kerr phase matching approach, allows for greater frequency separation between the region of optimal gain and pump, \textit{in situ} tunability of the pump, minimal gain ripple, and a compact footprint which reduces losses. A TWPA employing the inverse Kerr phase matching technique experimentally demonstrated 20 dB of gain over a 3 GHz instantaneous bandwidth, with a tunable bandwidth of 8 GHz, minimal gain ripple, and near quantum-limited noise performance, with 1.5 photons of added noise.