Bayan Karimi
Espoo
ZOOM LINK TO JOIN IN: http://s.ic.fo/QTD_Transport191020
Monday Oct 19, 2020 / 17:00-17:30 CEST
Towards single microwave photon detection by nanocalorimetry
Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland
We used quantum trajectory techniques to analyze a realistic set-up of a superconducting qubit coupled to a heat bath formed by a resistor. We discuss the main characteristics of the jump trajectories and relate them to the expected outcomes “clicks” of a fluorescence measurement using this resistor as a nano-calorimeter. We present a model that predicts the time domain response of this nanocalorimeter subject to single microwave photons [1]. For this purpose, we developed experimentally a nanocalorimeter that reaches the fundamental limit of resolving such quanta, bounded by the fluctuations due to temperature, which is able to measure continuously and almost noninvasively [2].
[1] Bayan Karimi and Jukka P. Pekola Quantum trajectory analysis of single microwave photon detection by nanocalorimetry, Phys. Rev. Lett. 124, 170601 (2020).
[2] Bayan Karimi, Fredrik Brange, Peter Samuelsson, and Jukka P. Pekola, Reaching the ultimate energy resolution of a quantum detector, Nat. Comm. 11, 367 (2020).
Hi Bayan, nice talk. I was wondering whether is possible to activate more energy levels in the setup for rectification. In other words, is it possible to have a controllable superconducting systems going from the linear to the nonlinear regime to control te rectification?
Hi Guillermo,
Yes, we have in general a multilevel system, where the anharmonicity (non-linearity) is controlled by the Josephson energy of the SQUID, which is tunable by magnetic field. Different types of qubits have very different anharmonicity. In some of them you can have almost pure 2-level system, the others (like the transmon in this experiment) is almost harmonic. In the experiments now we consider levels up to the sixth one currently.
Thanks a lot for your reply. It is indeed interesting to have a tunable rectifier. I will take a look to your interesting experimental articles. Thanks a lot.