Nanometer Resolution and Coherent Optical Dipole Coupling of Two Individual Molecules
C. Hettich,1
C. Schmitt,1
J. Zitzmann,2
S. Kühn,2
I. Gerhardt,2
V. Sandoghdar2*
By performing cryogenic laser spectroscopy under a
scanning probe electrode that induces a local electric field, we have
resolved two individual fluorescent molecules separated by 12 nanometers in an organic crystal. The two molecules undergo a strong
coherent dipole-dipole coupling that produces entangled sub- and
superradiant states. Under intense laser illumination, both molecules
are excited via a two-photon transition, and the fluorescence from this
doubly excited system displays photon bunching. Our experimental scheme can be used to optically resolve molecules at the nanometer scale and
to manipulate the degree of entanglement among them.
1 Department of Physics, University of
Konstanz, 78457 Konstanz, Germany.
2 Physical
Chemistry Laboratory, Swiss Federal Institute of Technology (ETH),
CH-8093 Zurich, Switzerland.
*
To whom correspondence should be addressed. E-mail:
vahid.sandoghdar{at}ethz.ch
