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

• Creating photon-number squeezed strong microwave fields by a Cooper-pair injection laser, Phys. Rev. B 95, 134515 (2017)
  Koppenhöfer, Martin; Leppäkangas, Juha & Marthaler, Michael
  
• Multiplying and detecting propagating microwave photons using inelastic Cooper pair tunneling, Phys. Rev. A 97, 013855 (2018)
  Leppäkangas, Juha; Marthaler, Michael; Hazra, Dibyendu; Jebari, Salha; Albert, Romain; Blanchet, Florian; Johansson, Göran & Hofheinz, Max
  
• Quantum simulation of the spin-boson model with a microwave circuit, Phys. Rev. A 97, 052321 (2018)
  Leppäkangas, Juha; Braumüller, Jochen; Hauck, Melanie; Reiner, Jan-Michael; Schwenk, Iris; Zanker, Sebastian; Fritz, Lukas; Ustinov, Alexey V.; Weides, Martin & Marthaler, Michael
  
• Resonance inversion in a superconducting cavity coupled to artificial atoms and a microwave background
  Leppäkangas, Juha; Brehm, Jan David; Yang, Ping; Guo, Lingzhen; Marthaler, Michael; Ustinov, Alexey V. & Weides, Martin