Two-Level System as a Quantum Sensor for Absolute Calibration of Power

Teresa Hönigl-Decrinis, Rais Shaikhaidarov, S.E. de Graaf, Vladimir Antonov, Oleg Astafiev

Research output: Contribution to journalArticlepeer-review

116 Downloads (Pure)


A two-level quantum system can absorb or emit not more than one photon at a time. Using this fundamental property, we demonstrate how a superconducting quantum system strongly coupled to a transmission line can be used as a sensor of the photon flux. We propose four methods of sensing the photon flux and analyse them for the absolute calibration of power by measuring spectra of scattered radiation from the two-level system. This type of sensor can be tuned to operate in a wide frequency range, and does not disturb the propagating waves when not in use. Using a two-level system as a power sensor enables a range of applications in quantum technologies, here in particular applied to calibrate the attenuation of transmission lines inside dilution refrigerators.
Original languageEnglish
Article number024066
Pages (from-to)1-9
Number of pages9
JournalPhysical Review Applied
Issue number2
Publication statusPublished - 25 Feb 2020


  • superconducting qubit
  • quantum sensing
  • superconducting quantum optics
  • microwaves

Cite this