Nanomechanics Group

Prof. Dr. Eva Weig

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Mechanical manipulation of nanomechanical resonators

We perform experiments where an atomic force microscope (AFM) tip acts as a local perturbation on the resonator’s clamping point. The interaction of the AFM tip with the clamping points enables direct mechanical manipulation of the oscillation with controlled position and contact force.

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J. Rieger, A. Isacsson, M. J. Seitner, J. P. Kotthaus, E. M. Weig,
Nature Communications 5, 3345 (2014)

Frequency and Q factor control of nanomechanical resonators

We present an integrated scheme for dielectric drive and read-out of high-Q nanomechanical silicon nitride string resonators which enables tuning of both the resonance frequency and the quality factor with an applied dc voltage [1].

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[1] J. Rieger, T. Faust, M. J. Seitner, J. P. Kotthaus, and E. M. Weig, Appl. Phys. Lett. 101 103110 (2012)

Coherent control of a classical nanomechanical two-level system

We realize a classical nanomechanical two-level system driven by radiofrequency signals.
It is based on the two orthogonalo fundamental flexural modes of a high-quality factor nanostring resonator that are strongly coupled by dielectric gradient fields. Full Bloch sphere control is demonstrated by means of Rabi, Ramsey and Hahn echoo experiments.

 

T. Faust, J. Rieger, M. J. Seitner, J. P. Kotthaus, E. M. Weig, Nature Physics, 2013, 9, 485-488
* see also News and Views: "Nanomechanical resonators: Spinning oscillators", by Klemens Hammerer, 02-07-2013.

Nonadiabatic dynamics of two strongly coupled nanomechanical resonator modes

The Landau-Zener transition [1,2] is a fundamental concept for dynamical quantum systems and has been studied in numerous fields of physics. Here we present a classical nanomechanical model system exhibiting analogous behaviour [3].

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[1] L. D. Landau, Phys. Z. Sowjetunion 2, 46 (1932)

[2] C. Zener, Proc. R. Soc. London, Ser. A 137, 696 (1932)

[3] T. Faust, J. Rieger, M.J. Seitner, P. Krenn, J.P. Kotthaus and E.M. Weig, Phys. Rev. Lett. 109, 037205 (2012)

Cavity Nano-Optomechanics

Directly probing the mechanical motion of nanoscale objects is a challenging task because of their small dimensions. One example for such molecular scale mechanical resonators are freely suspended, doubly clamped carbon nanotubes (CNTs) with resonance frequencies in the hundred kilohertz range.

To detect the vibration of such a CNT a fiber-based optical micro cavity is employed, as small mode volume optical cavities of high finesse are precise instruments to read out the mechanical motion of objects much smaller than the optical wavelength.

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See Favero et al., Optics Express, doi:10.1364/OE.17.012813
and Favero et al., New Journal of Physics, doi:10.1088/1367-2630/10/9/095006
and S. Stapfner et al., Appl. Phys. Lett. 102, 151910 (2013);for details.

Dielectric transduction of nanomechanical systems

Any polarizable object exposed to an inhomogeneous field will experience a force. We employ this simple concept as an innovative and highly efficient scheme to transduce nanomechanical resonators by a dielectric gradient force generated by electrodes located beneath the resonator. Not only is the described method local and integrable, it is also scalable to large bandwith and does not require any beam metallization which might introduce extra dissipation.

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See Unterreithmeier et al., Nature 458, 1001 (2009)
and T. Faust et al., Nat. Commun. 3,728 (2012) for details.

Electromechanical charge shuttle

A gold island is hosted in the center of a doubly-clamped high stress silicon nitride beam that is actuated accoustically to oscillate between an adjacent source and drain electrode. In this project, we investigate the nanomechanical transport of N electrons that are shuttled with the resonance frequency f of the moving island, giving rise to a current of I = 2Nef.

http://www.nano.physik.uni-muenchen.de/nanomech/research_shuttle.html(Click here to read more)

 


See König et al., Nature Nanotechnology, doi:10.1038/nnano.2008.178
or article on nanotechweb.org (in English)
and Michael J. Moeckel et al., New Journal of Physics 16 (2014) 043009 for details.

Pillar mechanics

We employ an array of flexible nanopillars vertically etched into a GaAs wafer to explore the dynamics of living cells in an artificial environment. In terms of biosensing, the pillar mechanics is used as sensitive force transducer for living cells.

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P. Paulitschke, N. Seltner, A. Lebedev, H. Lorenz, E. M. Weig,
Appl. Phys. Lett. 103, 261901 (2013)