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Superconducting Josephson devices for quantum measurements in electronic circuits

October 22, 2015 - 2:00pm
Maxim Vavilov

Recent experiments revealed the quantum nature of electromagnetic fields of superconducting circuits at microwave frequencies. Individual quanta of these fields are photons with energy a few million times smaller than the energy of an optical photon and are extremely hard to detect. A promising device for microwave photon detection is based on Josephson junctions. Even a single microwave photon with tiny energy is sufficient to switch a junction from the superconducting to voltage state, and detection of a photon reduces to observation of voltage pulses across the junction.
In this talk, I will present a theoretical model of a current-bias Josephson junction interacting with a quantized electromagnetic field and show that Josephson photon detectors have relatively high efficiency of detection of a single microwave photon. I will also describe gain and added noise in SQUID amplifiers by analyzing effect of thermal noise on phase-slips timing.
I will discuss application of such devices for qubit readout for quantum information processing and to studies of photon emission statistics by quantum electronic devices.

John S Toll Physics Bldg Room 1201
College Park, MD 20742

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