Nonlinear optics with a single molecule and only a few photons

Photons do not usually interact. This is why in linear optics two laser beams can cross without clashing like two swords. In nonlinear optical materials, however, photons can interact with one another, opening the door to logic operations. This is of great interest in nano-quantum-optics, where one dreams of nanoscopic quantum networks. Normal nonlinear optics requires, however, intense laser pulses and macroscopic chunks of material containing huge numbers of atoms. One way to access the nonlinear regime with single molecules and single photons has been to use high-Q microcavities. We have recently succeeded in demonstrating nonlinear optical effects using a single molecule and only a few photons. The key has been to realize that tight focusing and the intrinsic nonlinearity of a quantum two-level system are actually sufficient. In the experiment, we focus two very weak laser beams onto a molecule in a crystal at liquid helium temperature. Depending on the parameters of one beam, the other could either be attenuated or amplified. We are also able to generate new frequencies.  

Few-photon coherent nonlinear optics with a single molecule

A. Maser, B. Gmeiner, T. Utikal, S. Götzinger, and V. Sandoghdar Nature Photonics 10, 450 (2016)

In press:

Max Planck Society - Research News: A tiny switch for a few particles of light (2016) by Peter Hergersberg

FAU aktuell: Ein winziger Schalter für ein paar Lichtteilchen (2016)

Phys.org: A tiny switch for a few particles of light (2016)