Mohammad Musavinezhad

Quantum Efficiency of Single Dibenzoterrylene Molecules in p-Dichlorobenzene at Cryogenic Temperatures

Mohammad Musavinezhad, Alexey Shkarin, Dominik Rattenbacher, Jan Renger, Tobias Utikal, Stephan Götzinger, Vahid Sandoghdar

We measure the quantum efficiency (QE) of individual dibenzoterrylene (DBT) molecules embedded in p-dichlorobenzene at cryogenic temperatures. To achieve this, we combine two distinct methods based on the maximal photon emission and on the power required to saturate the zero-phonon line to compensate for uncertainties in some key system parameters. We find that the outcomes of the two approaches are in good agreement for reasonable values of the parameters involved, reporting a large fraction of molecules with QE values above 50%, with some exceeding 70%. Furthermore, we observe no correlation between the observed lower bound on the QE and the lifetime of the molecule, suggesting that most of the molecules have a QE exceeding the established lower bound. This confirms the suitability of DBT for quantum optics experiments. In light of previous reports of low QE values at ambient conditions, our results hint at the possibility of a strong temperature dependence of the QE.

High-resolution Cryogenic Spectroscopy of Single Molecules in Nanoprinted Crystals

Mohammad Musavinezhad, Jan Renger, Johannes Zirkelbach, Tobias Utikal, Claudio U. Hail, Thomas Basché, Dimos Poulikakos, Stephan Götzinger, Vahid Sandoghdar

We perform laser spectroscopy at liquid helium temperatures (T=2 K) to investigate single dibenzoterrylene<br>(DBT) molecules doped in anthracene crystals of nanoscopic height fabricated by electrohydrodynamic dripping.<br>Using high-resolution fluorescence excitation spectroscopy, we show that zero-phonon lines of single molecules<br>in printed nanocrystals are nearly as narrow as the Fourier-limited transitions observed for the same guest-host<br>system in the bulk. Moreover, the spectral instabilities are comparable to or less than one linewidth. By<br>recording super-resolution images of DBT molecules and varying the polarization of the excitation beam, we<br>determine the dimensions of the printed crystals and the orientation of the crystals’ axes. Electrohydrodynamic<br>printing of organic nano and microcrystals paves the way for a series of applications, where controlled positioning<br>of quantum emitters with narrow optical transitions is desirable.