Research

In my research I investigate how quantum physics can be tested and exploited with large molecules and nanoparticles. My activities fall into three categories:

  • Levitated opto- and electromechanics with aspherical nanoparticles
  • Decoherence, friction, and diffusion of quantum rigid rotors
  • Molecular matter-wave interferometry

Levitated opto- and electromechanics

Optically or electrically levitating nano- to microscale dielectrics in ultrahigh vacuum provides an attractive platform for testing quantum physics. In the last years we have demonstrated theoretically and experimentally how the center-of-mass motion and rotation of cylindrically shaped nanorotors can be precisely controlled with laser fields. Recently, we put forward a proposal to witness the quantization of their angular momentum by observing so-called orientational quantum revivals.

Key publications:

  • Probing macroscopic quantum superpositions with nanoscale rotors
    B. A. Stickler, B. Papendell, S. Kuhn, B. Schrinski, J. Millen, M. Arndt, and K. Hornberger
    New J. Phys. 20, 122001 (2018)
  • Optically driven ultra-stable nanomechanical rotor
    S. Kuhn, B. A. Stickler, A. Kosloff, F. Patolsky, K. Hornberger, M. Arndt, and J. Millen
    Nat. Commun. 8, 1670 (2017)
  • Ro-translational cavity cooling of dielectric rods and disks
    B. A. Stickler, S. Nimmrichter, L. Martinetz, S. Kuhn, M. Arndt, and K. Hornberger
    Phys. Rev. A 94, 033818 (2016)

Orientational decoherence of quantum rigid rotors

A nanoscale rigid rotor revolving in a homogeneous background gas experiences random collisions with the surrounding gas atoms. These collisions lead to a gradual loss of orientational coherence, and thus classicalize the quantum state of the rotor. In several recent works, we developed the theory of environmental decoherence, friction, and thermalization of arbitrarily shaped quantum rigid rotors. Application of the derived equations to a recent experiment with nitrogen superrotors yields excellent agreement.

Key publications:

Molecular matter-wave interference

The interference pattern of large molecules crucially depends on how the particles interact with the diffraction grating. This provides an attractive way to access otherwise elusive molecular properties, such as their optical polarizabilities or absorption cross sections. On the other hand, their interaction with the grating can be used to control the quantum state of the molecules. In recent works we investigated the role of molecular rotations in matter wave interference, and we showed how a combination of molecular diffraction and spatial filtering serves to separate different conformers.

Key publications:

  • Conformer-selection by matter-wave interference
    C. Brand, B. A. Stickler, C. Knobloch, A. Shayeghi, K. Hornberger, and M. Arndt
    Phys. Rev. Lett. 121, 173002 (2018)
  • On the role of the electric dipole moment in the diffraction of biomolecules at nanomechanical gratings
    C. Knobloch, B. A. Stickler, C. Brand, M. Sclafani, Y. Lilach, T. Juffmann, O. Cheshnovsky, K. Hornberger, and M. Arndt
    Fortschr. Phys. 65, 1600025 (2017)
  • Molecular rotations in matter wave interferometry
    B. A. Stickler and K. Hornberger
    Phys. Rev. A 92, 023619 (2015)

Key collaborators