Non-classical electromagnetic radiation created by superconducting quantum circuits. A tool for highly sensitive spectroscopy.

• Applicant: Dr. Michael Marthaler
• Subject Area: Theoretical Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 277008891

• Final Report Year: 2019

Final Report Abstract

In the project we planed to pursue the following ideas: (i) to use superconducting quantum circuits as a source of non-classical electromagnetic radiation, and (ii) to use this radiation to enhance the signal to noise ratio for Raman spectroscopy. During the project we first broadened the scope by considering unconventional photon creation on the few photon level and then by working on using structures similar to quantum metamaterials for quantum simulation. At last we also worked closely with experimental physicists on the characterization of quantum metamaterials.

Publications

• Resonance inversion in a superconducting cavity coupled to artificial atoms and a microwave background
  J. Leppäkangas, J. D. Brehm, P. Yang, L. Guo, M. Marthaler, A. V. Ustinov, M. Weides
  (See online at https://doi.org/10.1103/PhysRevA.99.063804)
• Creating photon-number squeezed strong microwave fields by a Cooper-pair injection laser, Phys. Rev. B 95, 134515 (2017)
  M. Koppenhöfer, J. Leppäangas, Michael Marthaler
  (See online at https://doi.org/10.1103/PhysRevB.95.134515)
• Multiplying and detecting propagating microwave photons using inelastic Cooper pair tunneling, Phys. Rev. A 97, 013855 (2018)
  J. Leppäkangas, M. Marthaler, D. Hazra, S. Jebari, R. Albert, F. Blanchet, G. Johansson, M. Hofheinz
  (See online at https://doi.org/10.1103/PhysRevA.97.013855)
• Quantum simulation of the spin-boson model with a microwave circuit, Phys. Rev. A 97, 052321 (2018)
  J. Leppäkanu gas, J. Braumüller, M. Hauck, J.-M. Reiner, I. Schwenk, S. Zanker, L. Fritz, A. V. Ustinov, M. Weides, M. Marthaler
  (See online at https://doi.org/10.1103/PhysRevA.97.052321)