Research Group Hunger

Cavity Quantum Optics
Cavity with Diamond MembraneD. Hunger

Our group is exploring applications of optical microcavities in the fields of solid state quantum optics, optical sensing, microscopy, spectroscopy, and optomechanics.


Enhanced light-matter interactions allow one to realize efficient optical interfaces at the single quantum level, and enable novel schemes for spectroscopy and sensing. We employ and further develop fiber-based Fabry-Perot microcavities, which combine microscopic mode volumes with exceptionally high quality factors, and at the same time offer open access for a variety of samples. We use this highly flexible platform e.g. to realize a coherent spin-photon interface for NV centers in diamond, to read out and control individual rare earth ions as qubits, and to perform cavity-enhanced sensing and spectroscopy of nanosystems also in liquid environments.

Cavity with CNTs D. Hunger
Cavity with spins
Optically addressable spin qubits with rare earth ions
Cavity with NVs
Spin-photon interface with color centers in diamond
Sensing of individual nanosystems in liquids
CNT Raman map
Cavity-enhanced spectroscopy of carbon nanotubes
WS2 Flake
Polaritons in atomically thin semiconductors
SCM Picture
Scanning cavity microscopy of nanosystems


  • 03/24: We have achieved record-long spin coherence in SnV centers in diamond, driven by a superconducting waveguide - see preprint on arxiv.
  • 11/23: We have observed collective effects from NV centers coupled to a microcavity - see preprint on arxiv.
  • 04/23: We have realized an ultra-stable cryogenic nanopositioning platform which achieves picometer-scale stability for an open Fabry-Perot cavity in a closed-cycle cryostat - see paper in APL Photonics
  • 12/22: Summary article on scanning cavity microscopy published in Imaging&Microscopy
  • 11/22: 3D laser-printed microstructures on fiber endfacets are a new and versatile approach to realize Fabry-Perot microcavities - see the paper in Optics Express
  • 10/22: We have studied the effect of a diamond membrane on the modes of an open cavity to understand the achievable performance of spin-photon interfaces for color centers - see the preprint on arxiv
  • 04/22: We are part of the BMBF Grand Challenge on Quantum communication with the project NEQSIS, see the press release of TUM
  • 03/22: We are part of the BMBF Project SPINNING with the goal to realize a quantum computer based on spin qubits in diamond
  • 03/22: We have observed ultra-long optical coherence in molecular Rare Earth ion complexes, published in Nature
  • 11/21: We have developed a novel scheme for 3D tracking of Brownian motion and cavity-enhanced sensing of nanoparticles in liquids - finally published in Nature Communications
  • 08/21: We are co-organizing an exciting Heraeus Workshop on optically addressable spins - contact us to participate remotely!
  • 08/21: BMBF-founded project "Quantum Repeater Link" (QR.X) is starting as an extension of We will contribute to realize a quantum repeater link based on color centers in diamond within Germany, see here for a press release, here for project infos of the BMBF, and here for the project website.
  • 07/21: Bernardos paper on dynamical control of Purcell enhancement finally appeared at Nature Communications - congratulations!
  • 10/19: From our group emerges the spin-off Qlibri, developing stable optical fiber micro cavities for quantum optics and cavity enhanced absorption microscopes.
  • 10/19: We could explain artefacts in scanning cavity microscopy, see the new paper.
  • 09/19: Our paper on Polariton hyperspectral imaging in WS2 is (finally!) published
  • 8/19: We have hosted the Quantum Futur Academy with more than 30 participants.
  • 7/19: We have hosted the SQUARE summer school with 60 participants.
  • 11/18: The Max Planck School of Photonics has launched, with a first call for students opened until 15.12.2018. We are participating and offer a PhD project within the school!
  • 10/18: The Quantum Flagship is now officially announced, and with it the project SQUARE where we are part of. Have a look at the press release and webpage SQUARE.