My research investigates 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 nanorotors can be precisely controlled with laser fields. Recently, we put forward a proposal to witness orientational quantum revivals and the quantum version of the tennis-racket effect.

Key publications:

  • Quantum persistent tennis racket dynamics of nanorotors
    Y. Ma, K. Khosla, B. A. Stickler, and M. S. Kim
    Phys. Rev. Lett. 125, 053604 (2020)
  • 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)

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 demonstrated Bragg diffraction of large molecules, showed how a combination of molecular diffraction and spatial filtering serves to separate different conformers, and investigated the role of molecular rotations in molecule interference.

Key publications:

Key collaborators