Quantum Optomechanics

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).

Alumni:

• 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)

Ultracoherent mechanical devices

Doing quantum physics with nano- and micro-mechanical systems requires thorough understanding of mechanical decoherence and careful device engineering to avoid them all. We have accumulated many years of experience in this area, and apply it to build ever more coherent mechanical systems.

Most recently:

Our group has introduced soft-clamped mechanical resonators with unprecedented lifetimes of their quantum states. We are already using these devices in our experiments. But we keep pushing the frontier of ultracoherent mechanical systems, developing new device concepts for their numerous applications. One of particular interest is that of a new generation of force sensors for scanning imaging modalities, such as MRFM.

This research combines aspects of materials science, mechanical engineering and nanotechnology, and we apply methods ranging from finite-element modelling and advanced nanofabrication to milliKelvin cryogenics and various optical characterization techniques.

Quantum correlations and entanglement in optomechanical systems

When photons reflect off a movable object, momentum is transferred. This creates 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.

We study these quantum correlations and seek to harness them for quantum sensors—including gravity wave observatories such as LIGO—and quantum information processing. Recently, for example, we could demonstrate measurements of force and position with a sensitivity better than the standard quantum limit (SQL), and entanglement optical fields of widely different frequency. Tailoring entanglement and correlations in complex multi-mode systems and practical sensing settings is a goal of future research.

This research combines aspects of experimental and theoretical quantum optics, optomechanics and quantum information.

Quantum measurement and control of mechanical states

In the quantum description of the world, measurement assumes a special role, not least due to its inevitable “backaction” on the measured system. The associated questions become particularly intriguing when studied with objects visible to the bare eye.

We elucidate those by applying modern quantum theory to an optomechanical setting. This allows us, for example, to predict and “retrodict” the quantum state of motion of a mechanical system from a measurement record. With such quantum measurements at hand, we can perform quantum feedback on the mechanical state.

In a recent work, we used this to suppress classical and quantum position fluctuations in a fashion similar to noise-cancelling headphones. In this manner, we can prepare mechanical systems in the quantum ground state. But other quantum states may be prepared as well, and new questions arise when considering the thermodynamics of such processes.

This research combines aspects of experimental and theoretical quantum optics and optomechanics, quantum measurement and quantum control theory.

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.

Our research is made possible by funding from the following sources:

• European Research Council
• European Training Network "Optomechanical technologies" (OMT)
• FET Proactive Project "Hybrid Optomechnaical Technologies" (HOT)
• Danish National Research Foundation
• Swiss National Science Foundation „Sinergia“
• Novo Nordisk Foundation (NERD)

Recent publications and preprints

2020

• R. A. Thomas, M. Parniak, C. Østfeldt, C. B. Møller, C. Bærentsen, Y. Tsaturyan, A. Schliesser, J. Appel, E. Zeuthen & E. S. Polzik Entanglement between distant macroscopic mechanical and spin systems Nature Physics (2020)
• 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)  Pre-print: arXiv:2007.08766
• 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) Preprint: arXiv:2006.06238
• M. Rossi, L. Mancino, G. T. Landi, M. Paternostro, A. Schliesser, & A. Belenchia Experimental assessment of entropy production in a continuously measured mechanical resonator. Phys. Rev. Lett. 125, 080601 (2020), arXiv:2005.03429v1
• E. Zeuthen, A. Schliesser, A.S. Sørensen & J. M. Taylor: Figures of merit for quantum transducers. Quantum Sci. Technol. 5 034009
• M. Brunelli, D. Malz, A. Schliesser & A. Nunnenkamp: Stroboscopic quantum optomechanics. Phys. Rev. Research 2, 023241 (2020), arXiv:2003.04361
• L. Catalini, Y. Tsaturyan & A. Schliesser: Soft-clamped phononic dimers for mechanical sensing and transduction. Phys. Rev. Applied 14, 014041 (2020), arXiv:2003.04072
• J. Chen, M. Rossi, D. Mason & A. Schliesser: Entanglement of propagating optical modes via a mechanical interface. Nature Communications 11, 943 (2020), arXiv:1911.05729

2019

• D. Mason, M. Rossi, J. Chen, Y. Tsaturyan, A. Schliesser: Interferometric Measurement Beyond the Quantum Limit. Optics in 2019, Special issue of OSA Optics and Photonics News

• A. Simonsen, J. D. Sanchez, S. A. Saarinen, J. H. Ardenkjaer-Larsen, A. Schliesser, E. S. Polzik: Magnetic resonance imaging with optical preamplification and detection. Scientific Reports volume 9, Article number: 18173 (2019), arXiv:1906.12260

• M. Rossi, D. Mason, J. Chen, A. Schliesser: Observing and Verifying the Quantum Trajectory of a Mechanical Resonator. Physical Review Letters 123, 163601 (2019), arXiv:1812.00928

• D. Mason, J. Chen, M. Rossi, Y. Tsaturyan, A. Schliesser: Continuous Force and Displacement Measurement Below the Standard Quantum Limit. Nature Physics 15, 745 (2019), arXiv:1809.10629, Press release

• A. Schliesser: Quantum Physics: Counting grains of sound. Nature 571, 480 (2019)

• 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)

2018

• M. Rossi, D. Mason, J. Chen, Y. Tsaturyan, A. Schliesser: Measurement-based quantum control of mechanical motion. Nature 563, 53 (2018), https://arxiv.org/abs/1805.05087, News and Views, Press Release, Science Breaker Story
• A. Barg, L. Midolo, G. Kirsanske, P. Tighineanu, T. Pregnolato, A. Imamoglu, P. Lodahl,
  S. Stobbe, A. Schliesser, E. S. Polzik: Carrier-mediated optomechanical forces in semiconductor nanomembranes with coupled quantum wells. Physical Review B 98, 155316 (2018)
• E. Zeuthen, A. Schliesser, J. M. Taylor, A. S. Sørensen,
  Electro-optomechanical equivalent circuits for quantum transduction. Physical Review Applied 10, 044036 (2018)
• L. Midolo, A. Schliesser, A. Fiore: Nano-Opto-Electro-Mechanical Systems. Nature Nanotechnology 13, 11 (2018)

2017

• Y. Tsaturyan, A. Barg, E. S. Polzik, A. Schliesser: Ultracoherent nanomechanical resonators via soft clamping and dissipation dilution. Nature Nanotechnology 12, 776 (2017)
• C. B. Møller, R. A. Thomas, G. Vasilakis, E. Zeuthen, Y. Tsaturyan, M. Balabas, K. Jensen,
  A. Schliesser, K. Hammerer, E. S. Polzik: Quantum back-action-evading measurement of motion in a negative mass reference frame. Nature 547, 191 (2017)
  
• H. P. Nielsen, Y. Tsaturyan, C. B. Moller, E. S. Polzik, A. Schliesser: Multimode optomechanical system in the quantum regime. Proceedings of the National Academy of Sciences of the USA (2017), https://arxiv.org/abs/1605.06541, Press Release
• T. Capelle, Y. Tsaturyan, A. Barg, A. Schliesser: Polarimetric analysis of stress anisotropy in nanomechanical silicon nitride resonators. Applied Physics Letters 110, 181106 (2017)
  
• A. Barg, Y. Tsaturyan, E. Belhage, W. H. P. Nielsen, C. B. Møller, A. Schliesser: Measuring and imaging nanomechanical motion with laser light. Applied Physics B 123, 8 (2017)
  

List of major publications and patents can be found here.

Full list, including doi links, is available here.

We are always looking for motivated and dedicated students!

Bachelor Project opportunities
Please contact Prof. Albert Schliesser at albert.schliesser*nbi.dk if you are interested.

Master Project opportunities
Please contact Prof. Albert Schliesser at albert.schliesser*nbi.dk if you are interested.

PhD positions
Please contact Prof. Albert Schliesser at albert.schliesser*nbi.dk if you are interested.

PostDoc positions
Please contact Prof. Albert Schliesser at albert.schliesser*nbi.dk if you are interested.

Albert Schliesser, Professor and groupleader
Blegdamsvej 17
2100 København Ø
Building F & T, Office: 12-1-TB3
Email: albert.schliesser@nbi.ku.dk
Phone: +45 35 32 54 01
 

Charlotte Hviid, Administrative coordinator
Niels Bohr Institute
Blegdamsvej 17
2100 København Ø.
Office: Bygning T, Ta2a
E-mail: hviid@nbi.ku.dk
Phone: +45 353-25254

Frederik Uldall, Centre coordinator 
Office: Bygning T, Ta2a
E-mail: frederik.uldall@nbi.ku.dk

Office phone: +45 35 32 24 14