A Quantum Paraelectric Parametric Amplifier

Cryogenic amplification of radio frequency signals is a key technology for quantum information processing, radio astronomy and other fields. While wideband transistor-based amplifiers are abundantly available, their intrinsic noise floor typically lies around a few K noise temperature, higher than the mK physical temperatures routinely achieved in dilution refrigerators. Parametric amplifiers employing superconducting nonlinearities to implement parametric drive close this gap, but at the cost of high susceptibility to magnetic fields and low power handling capabilities. An alternative route to achieving parametric drive is the use of quantum paraelectrics – a class of materials whose dielectric constant is highly tuneable by electric fields at cryogenic temperatures. Here, we demonstrate parametric amplification by three-wave mixing using cryogenic hyperabrupt varactors (voltage-tuneable capacitors) based on the quantum paraelectric strontium titanate. We report gains exceeding 30 dB with a tuneable operation frequency around 150 MHz and excellent power handling with a 1dB compression point at -35 dBm input signal for 20 dB gain. We further study the devices B-field resilience, noise performance and the impact of design and electrode materials on performance.