AQP -seminaari: Towards a sensitive microwave photon detection

Aalto Quantum Physics seminaari (Micronova). Puhuja: Prof.Evgeni Il’ichev (Leibniz Institute of Photonic Technology, Germany)

Recently we got EU project entitled “Highly sensitive detection of single microwave photons with a coherent quantum network of superconducting qubits for searching galactic axions.” In my talk, I will present the basic ideas of the proposed method: detecting the signal simultaneously in several points of the quantum metamaterial sensor array.
To approach a realization of such a detector, first experiments have been performed, namely superconducting quantum metamaterials, realized as an array of different type of flux qubits, have been fabricated and tested. In the first set of experiments 20 flux qubits, are embedded into a microwave resonator. Collective mode of its operation was experimentally demonstrated [1].  In the second set of experiments the transmission of a microwave signal through a metamaterial based on double-loop flux qubits has been studied [2]. We observed the periodical dependence of the transmission on the applied magnetic field. Field-controlled change of the ground state configurations of the meta-atoms induces suppression of the transmission. 

References
 1. Pascal Macha, Gregor Oelsner, Jan-Michael Reiner, Michael Marthaler, Stephan Andre, Gerd Schön, Uwe Hübner, Hans-Georg Meyer, Evgeni Il'ichev, and Alexey V. Ustinov, 
 Nature Comm., 5, 5146, (2014)  

2. K. V. Shulga, E. Il'ichev, M. V. Fistul, I. S. Besedin, S. Butz, O. V. Astafiev. U. Hübner, A. V. Ustinov "Magnetically induced transparency of a quantum metamaterial composed of twin flux qubits," Nature Comm., 9, 150, (2018).