Quantum Optomechanics

The Schliesser group experiments with mechanical systems deeply in the quantum regime. We engineer mechanical resonators with extremely low dissipation, and probe them with optical and microwave photons. In this setting we push the quantum limit for measuring motion, investigate decoherence mechanisms and implement control and conversion schemes with mechanical quantum states.

We translate our findings to application in quantum technologies, such as novel quantum sensors for electromagnetic fields and forces, and mechanical interfaces that can store and convert quantum information in hybrid quantum networks. 

Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute Quantum Optomechanics at the Niels Bohr Institute
















The Schliesser group was established in 2015 at the historic Niels Bohr Institute in central Copenhagen.

The group is now around a dozen members strong, and usually comprises Bachelor, Master and PhD students, as well as postdocs, from all over the world.

We entertain active connections to the international Optomechanics community, with recent collaborations with i.a. ETH Zurich, TU Delft, Paris Saclay, Cambridge University and Caltech.

The group members

















































Ultracoherent mechanical devices

A phononic membrane resonator is at the heart of each of our experiments, functioning as an ultracoherent quantum system with built-in isolation from the environmental. Normal crystals are a collection of atoms with a repeating pattern, imbuing the material with special characteristics. Similarly, a phononic crystal is a fabricated object with a repeating pattern that gives it a particularly useful property – a bandgap that forbids the propagation of motion at certain frequencies. This allows us to ‘trap’ a mechanical resonance within the phononic crystal, creating a well-packaged quantum system. 

More info.

Quantum Transduction

Transduction between optical light and microwaves by means of a mechanical interface.

While microwave solid state qubits have demonstrated very efficient quantum protocols over the years, their fragile quantum states have yet been trapped at the bottom of cryostats. On the other hand, optical fibers can transport a quantum state over kilometers without loosing its salient features.

At SLAB, we are developing a platform to transduce quantum information from microwave to optics by coupling an ultracoherent mechanical resonator to both an optical and a microwave cavity. This technology could enable the development of a large scale hybrid network, coined “quantum internet”, where each node would be a different cryostat.

More info.

Cavity Optomechanics: a versatile vehicle for quantum mechanics

Graph displaying the standard quantum limit

When photons reflect off a movable object, momentum is transferred. This idea of light exerting pressure on objects dates back to Kepler’s observation that comet tails are pointed away from the Sun. First considerations of this radiation pressure in the context of optomechanics are attributed to Braginsky, in the analysis of the light-induced modification of the frequency and damping rate of a movable mirror. We employ high-quality optical and mechanical resonators (see ultracoherent membrane resonators) to study optomechanical effects at the quantum level. This includes correlations, all the way down to the quantum fluctuations in the light and the motion. We can thereby also generate entanglement—the key resource for many quantum technologies—in an optomechanical system.

More info.

Hybrid spin-mechanics

Hybrid quantum systems, such as the textbook example of optically active 2-level systems coupled to cavity photons, are relevant for quantum technologies and foundations of quantum mechanics. Coupling a spin, which is an inherently quantum object, to a mesoscopic mechanical resonator could be used to enter a regime previously unattained in quantum optomechanics, which could ultimately lead to the generation of non-classical states of motion in a millimiter-sized membrane.

More info.

Mechanical interfaces and memories in hybrid quantum systems

Mechanical devices are of great interest as interfaces and memories in hybrid quantum systems. They are readily functionalized to couple to electromagnetic fields from the radio-frequency to the optical domain, as well as electron and nuclear spins.

Therefore they can act as coherent transducers between different platforms for quantum information processing—and from those to optical photons, to date the only viable long-distance carrier for quantum information. We develop such interfaces based on highly coherent mechanical systems. The long lifetime of their quantum states additionally allows storage of quantum information in mechanical degrees of freedom, an avenue we explore with non-classical states of light such as single photons.

This research combines aspects of experimental and theoretical quantum optics, opto- and electromechanics and quantum information.

More info.

Ultracoherent topological phononic systems

Similar to electrical wires and optical waveguides, phononic waveguides allow information transfer via phononic waves and then form a phononic circuit. Phononic waveguides have been established as good interconnect channels among different physical systems due to their direct and strong coupling to electrical, optical, and even spin systems, and also been proved practical for quantum signal transport. In our lab, we are applying dissipation dilution and soft clamping techniques to topological phononic system to largely reduce the phononic propagation loss. By coupling the phononic waveguides to superconducting system, we can thereby realize quantum information transfer.















































































































Publications and pre-prints from the Schliesser group:


  • A. Mashaal, L. Stefan, A. Ranfagni, L. Catalini, I. Chernobrovkin, T. Capelle, E. Langman, A. Schliesser: Strong Thermomechanical Noise Squeezing Stabilized by Feedback. arXiv:2403.02328


  • C.A. Rosiek, M. Rossi, A. Schliesser, A. S. Sørensen: Quadrature squeezing enhances Wigner negativity in a mechanical Duffing oscillator. arxiv:2312.12986
  • M. B. Kristensen, N. Kralj, E. C. Langman and A. Schliesser: A Long-lived and Efficient Optomechanical Memory for Light. Physical Review Letters, 132(10), 100802.
  • E. Planz, X. Xi, T. Capelle, E. C. Langman and A. Schliesser: Membrane-in-the-middle optomechanics with a soft-clamped membrane at milliKelvin temperatures. Optics Express, 31(25), 41773-41782.


  • G. Enzian, Z. Wang, A. Simonsen, J. Mathiassen, T. Vibel, Y. Tsaturyan, A. Tagantsev, A. Schliesser, E. S. Polzik: Phononically shielded photonic-crystal mirror membranes for cavity quantum optomechanics. Optics Express, 31(8)
  • S. Saarinen, N. Kralj, E. Langman, Y. Tsaturyan & A. Schliesser: Laser cooling a membrane-in-the-middle system close to the quantum ground state from room temperature. Optica 10(3)
    Highlighted in Phys.org ,YouTube and Raport Naukowa (polish TV media, article starts at 13:26).
  • Y. Seis, T. Capelle, E. Langman, S. Saarinen, E. Planz & A. Schliesser: Ground State Cooling of an Ultracoherent Electromechanical System. Nat. Comm. 13, 1507 (2022)
  • D. Hälg, T. Gisler, E. Langman, S. Misra, O. Zilberberg, A. Schliesser, C. L. Degen & A. Eichler: Strong parametric coupling between two ultra-coherent membrane modes. Phys. Rev. Lett. 128, 094301 (2022)
  • C. A. Rosiek: Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing. arXiv:2202.02285


  • A. Schliesser & S. Gröblacher: Quanten-mechanisch im Wortsinne. Phys. Unserer Zeit 52.6 (2021): 282-289, doi.org/10.1002/piuz.202101608
  • L. Catalini, M. Rossi, E. C. Langman & A. Schliesser: Modeling and Observation of Nonlinear Damping in Dissipation-Diluted Nanomechanical Resonators. Phys. Rev. Lett. 126, 174101 (2021)
  • D. Hälg, T. Gisler, Y. Tsaturyan, L. Catalini, U. Grob, M.-D. Krass, M. Héritier, H. Mattiat, A.-K. Thamm, R. Schirhagl, E. C. Langman, A. Schliesser, C. L. Degen & A. Eichler: Membrane-based scanning force microscopy. Phys. Rev. Appl. (2021)
    Highlighted in ABS.org.
  • M. A. Page, M. Goryachev, H. Miao, Y. Chen, Y. Ma, D. Mason, M. Rossi, C. D. Blair, L. Ju, D. G. Blair, A. Schliesser, M. E. Tobar & C. Zhao: Gravitational wave detectors with broadband high frequency sensitivity. Nat. Comm. Phys. (2021), arXiv:2007.08766
  • P. Seidler, E. Verhagen, A. Schliesser & A. Xuereb: Shining a HOT Light on Optomechanics. IEEE Spectrum (2021)
  • M. D. Sarto, L. Maggi, M. A. Shaw, A. Simonsen, A. Schliesser, M. Moraja, L. Mauri, M. Campaniello, D. Rotta, A. S. Rodrigo & A. Bogoni: Assembly of opto-mechanical devices. 2021 23rd European Microelectronics and Packaging Conference & Exhibition (EMPC) (2021)



  • A. Simonsen, J. D. Sanchez, S. A. Saarinen, J. H. Ardenkjaer-Larsen, A. Schliesser, E. S. Polzik: Sensitive optomechanical transduction of electric and magnetic signals to the optical domain. Optics Express 27, 18561 (2019)



For full list, see google scholar.


































































  • Yeghishe Tsaturyan — PhD 2019 — next step: Postdoc in Awschalom group, University of Chicago
  • David Mason — postdoc 2018-2020 — next step: Postdoc in Rakich group, Yale University
  • Massimiliano Rossi — PhD 2020 — next step: Postdoc in Novotny group, ETH Zurich
  • Junxin Chen — PhD 2021 — next step: Postdoc in LIGO group, MIT
  • Sampo Saarinen — PhD 2021 — next step: Quantum engineer at IQM
  • Yannick Seis — PhD 2021 — next step: Postdoc in Laboratoire de Physique, ENS de Lyon
  • Letizia Catalini — PhD 2022 — next step: Postdoc in Degen group, ETH Zurich
  • Nenad Kralj — postdoc 2019-2022 — next step: Independent research group leader, Max Planck Institute for Gravitational Physics
  • Eric Planz — PhD 2023 — next step: Quantum engineer at Quantum Machines























Albert Schliesser

Group leader

Albert Schliesser, Professor
Email: albert.schliesser@nbi.ku.dk
Phone: +45 35 32 54 01


Name Title Image
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Capelle, Thibault Adrien Postdoc Billede af Capelle, Thibault Adrien
Chernobrovkin, Ilia PhD Fellow Billede af Chernobrovkin, Ilia
Hahne, Felix Caspar Research Assistant Billede af Hahne, Felix Caspar
Konzett, Leopold PhD Fellow Billede af Konzett, Leopold
Kristensen, Mads Bjerregaard Postdoc Billede af Kristensen, Mads Bjerregaard
Langman, Eric Christopher Assistant Professor Billede af Langman, Eric Christopher
Mashaal, Aida PhD Fellow Billede af Mashaal, Aida
Pfau, Teresa Klara PhD Fellow Billede af Pfau, Teresa Klara
Pitts, Michael James Postdoc Billede af Pitts, Michael James
Ranfagni, Andrea Postdoc Billede af Ranfagni, Andrea
Schliesser, Albert Professor Billede af Schliesser, Albert
Tamaki, Sho Research Assistant Billede af Tamaki, Sho
Xi, Xiang Assistant Professor Billede af Xi, Xiang