Resolving quanta of collective spin excitations in a millimeter-sized ferromagnet

See allHide authors and affiliations

Science Advances  05 Jul 2017:
Vol. 3, no. 7, e1603150
DOI: 10.1126/sciadv.1603150


Combining different physical systems in hybrid quantum circuits opens up novel possibilities for quantum technologies. In quantum magnonics, quanta of collective excitation modes in a ferromagnet, called magnons, interact coherently with qubits to access quantum phenomena of magnonics. We use this architecture to probe the quanta of collective spin excitations in a millimeter-sized ferromagnetic crystal. More specifically, we resolve magnon number states through spectroscopic measurements of a superconducting qubit with the hybrid system in the strong dispersive regime. This enables us to detect a change in the magnetic moment of the ferromagnet equivalent to a single spin flipped among more than 1019 spins. Our demonstration highlights the strength of hybrid quantum systems to provide powerful tools for quantum sensing and quantum information processing.

  • Hybrid Quantum Systems
  • quantum magnonics
  • superconducting qubits
  • ferromagnetic insulators
  • magnons

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

View Full Text

Stay Connected to Science Advances