Wireless Josephson parametric amplifier above 20 GHz

TL;DR

This paper presents a wireless Josephson parametric amplifier operating above 20 GHz, achieving high gain and low noise, enabling better qubit readout at elevated temperatures.

Contribution

The design introduces a wireless architecture for Josephson parametric amplifiers, eliminating losses at high frequencies and demonstrating operation above 20 GHz.

Findings

Achieves over 20 dB gain from 21 to 23.5 GHz

Exhibits approximately two photons of added noise

Provides a tunable bandwidth of about 3 MHz

Abstract

Operating superconducting qubits at elevated temperatures offers increased cooling power and thus system scalability, but requires suppression of thermal photons to preserve coherence and readout fidelity. This motivates migration to higher operation frequencies, which demands high-frequency amplification with near-quantum-limited noise characteristics for qubit readout. Here, we report the design and experimental realization of a wireless Josephson parametric amplifier (WJPA) operating above 20~GHz. The wireless design eliminates losses and impedance mismatches that become problematic at high frequencies. The WJPA achieves more than 20~dB of gain across a tunable frequency range of 21--23.5~GHz, with a typical dynamic bandwidth of 3~MHz. Through Y-factor measurements and a qubit-based photon number calibration, we show that the amplifier exhibits an added noise of approximately two photons.