Audrey Bienfait (ENS-Lyon) Michelson Postdoctoral Prize Lecture

Date: Fri. February 21st, 2020, 12:45 pm-1:45 pm
Location: Rockefeller 221 (Les Foldy Room)

Microwave amplification at the quantum limit: implementing and operating a Josephson parametric amplifier

A microwave electromagnetic field cooled down to millikelvin temperatures can reach its ground state: at this stage, all thermal fluctuations are suppressed and only quantum fluctuations remain. Reaching this regime enabled manipulation of the microwave fields at the single-photon level but also required the development of ultra-low-noise microwave amplifiers to ensure the detection of these quantum microwave states. Relying on non-dissipative parametric amplification using Josephson junctions, these Josephson parametric amplifiers (JPA) perform amplification while adding as little noise as allowed by quantum mechanics. In this lecture, I will detail the principle of these amplifiers, their implementation, and their use for superconducting qubit state readout.