Observing the Dynamics of Dipole-Mediated Energy Transport by Interaction-Enhanced Imaging, in Science

By synthesising an artificial quantum system, we have simulated key processes of photosynthesis on a quantum level with high spatial and temporal resolution and discovered new properties of energy transport. This work is an important step towards answering the question how quantum physics can contribute to the efficiency of energy conversion in synthetic systems, for example in photovoltaics.

From a gas of ground state atoms we excited some atoms to highly excited Rydberg states. Similar to the light-harvesting complexes of photosynthesis, energy is transported from Rydberg atom to Rydberg atom, similar to a radio transmitter. To observe the transport of energy we use an electromagnetically induced transparency resonance, which makes up to 50 atoms absorb laser light within a characteristic radius around each Rydberg atom, making it possible to precisely measure the Rydberg atom distribution as a function of time. We were surprised to see that the Rydberg atoms quickly diffused from their original positions. Aided by a mathematical model we could show that the background gas of atoms crucially influences the energy transport dynamics, and the dynamics can be controlled by tuning the Rydberg-Rydberg interactions or the interaction with the laser fields.

G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, V. Gavryusev, S. Helmrich, C.S. Hofmann, S. Whitlock, M. Weidemüller, Science 342, 954-956 (2013)