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 Optomechanicsat 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.

Financial supported is generously provided by the European Research Council, Danmarks Grundforskningsfond, and the Swiss National Science Foundation. We entertain active connections to the international Optomechanics community through several EU-funded networks (such as HOT and OMT).

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. 

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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.

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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.

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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.

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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.

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Recent publications and preprints


  • Y. Seis, T. Capelle, E. Langman, S. Saarinen, E. Planz, A. Schliesser Ground State Cooling of an Ultracoherent Electromechanical System arXiv:2107.05552 (pre-print)
  • L. Catalini, M. Rossi, E. C. Langman, and A. Schliesser Modeling and Observation of Nonlinear Damping in Dissipation-Diluted Nanomechanical Resonators Phys. Rev. Lett. 126, 174101 (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)



List of major publications and patents can be found here.

Full list, including doi links, is available here.






















































































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
Catalini, Letizia PhD Fellow Billede af Catalini, Letizia
Hahne, Felix Caspar PhD Fellow Billede af Hahne, Felix Caspar
Kralj, Nenad Postdoc Billede af Kralj, Nenad
Kristensen, Mads Bjerregaard PhD Fellow Billede af Kristensen, Mads Bjerregaard
Langman, Eric Christopher Postdoc Billede af Langman, Eric Christopher
Planz, Eric PhD Fellow Billede af Planz, Eric
Saarinen, Sampo Antero Research Assistant Billede af Saarinen, Sampo Antero
Schliesser, Albert Professor Billede af Schliesser, Albert
Seis, Yannick PhD Student Billede af Seis, Yannick
Simonsen, Anders Postdoc Billede af Simonsen, Anders
Stefan, Lucio Postdoc Billede af Stefan, Lucio
Tamaki, Sho PhD Fellow Billede af Tamaki, Sho


  • Junxin Chen (now at MIT)
  • Massimiliano Rossi (now at ETH Zürich)
  • Yeghishe Tsaturyan (now at University of Chicago)
  • Christoffer Møller (now at ICFO Barcelona)
  • Andreas Barg (now at 3Shape)
  • William Nielsen (now at Microsoft station Q)