Photons are ideal carriers of quantum information. They can be precisely manipulated, are well decoupled from the environment and can be transported over long distances using optical fibers. To implement optical quantum networks, efficient interfacing of quantum emitters with light fields is required and scalability of these systems is sought.
The here proposed project will interface single organic molecules with the evanescent light field guided by an optical nanofiber. The molecules embedded in a crystal host that ensured stability and allows spectrally addressing single molecules by a narrowband laser. This is possible as every molecule sees a slightly different environment and therefore has a slightly different resonance transition frequency. These nanocrystals are deposited on the surface of the optical nanofiber and the strong transverse confinement of the light field ensures that the interaction with a single molecule can be significant. We will use this new platform to study fundamental questions in quantum optics and to implement important components of a quantum network.
We will study the nonlinear effect that a single molecule induces on the light field and using this effect realise a photon sorter, which is a number resolving detector for photons. This is not only a desired component in itself but a key constituent of more complex devices for quantum networks. The brightness of single molecules in solids together with their favorable internal level structure makes them a natural choice for single photon sources at a wide range of wavelengths. We will show the implementation of a stable, triggered single photon source by coupling a single molecule to a Fiber Bragg grating (FBG) resonator which will enhance emission into the optical nanofiber. A triggered single photon source is a prerequisite for linear optical quantum computation and can be used to perform sub-shot noise spectroscopy.
As the cavity increases the coupling of the molecules to the light field, this experimental platform allows the study of long range interactions between a distinct number of single molecules. The transition frequency of these molecules can be changed by an applied electric field and this is exploited to tune single molecules into resonance with each other. The interactions between different single molecules induced by the light field open up a wealth of experiments in nano-optics and for the implementation and control of entanglement in such solid state systems, an effect which lies at the core of quantum technologies.
