Iranian scientist has succeeded to build the world's smallest radio station by which two molecules communicate through single photons.
Scientists at ETH Zurich and Max Planck Institute for the Science of Light in Erlangen led by Iranian Professor Vahid Sandoghdar have shown that even one flying photon can interact with a single atom or molecule.
Providing a suitable source of single photons with a proper frequency and bandwidth was the key challenge in the way of performing such an experiment.
When an atom or molecule absorbs a photon it makes a transition to a so-called excited state. After a few nanoseconds (one thousand millionth of a second) this state decays to its initial ground state and emits exactly one photon.
The group used two samples containing fluorescent molecules embedded in organic crystals and cooled them to about 1.5 K (-272 °C).
Single molecules in each sample were detected by a combination of spectral and spatial selection.
To generate single photons, a single molecule was excited in the "source" sample. When the excited state of the molecule decayed, the emitted photons were collected and tightly focused onto the "target" sample at a distance of a few meters. To ensure that a molecule in that sample "sees" the incoming photons, the team had to make sure that they have the same frequency.
Furthermore, the precious single photons had to interact with the target molecule in an efficient manner. A molecule is about one nanometer in size (100000 times smaller than the diameter of a human hair) but the focus of a light beam cannot be smaller than a few hundred nanometers. In this process, the molecule acts as an antenna that grabs the light waves in its vicinity.
This experiment opens many doors for further exciting experiments in which single photons act as carriers of quantum information to be processed by single emitters.
Born on April 29, 1966 in Tehran (Iran) Vahid Sandoghdar, is Bachelor of Science in Physics from the University of California in Davis (1987), Ph.D. in Physics from Yale University (1993), Postdoctoral Fellow at Ecole Normale Superieure in Paris, Head of the Nano-Optics group und habilitation in Physics at University Konstanz. He enjoys the Professorship at Eidgenossischen Technischen Hochschule (ETH) Zurich (2001-2011). He is also Founder of the Network of Optical Sciences (opt ETH) and the Zurich Center for Imaging Science and Technology (CIMST) at ETH.
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