Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Key Processes of Photosynthesis Simulated on the Quantum Level

11.11.2013
Physicists discover new properties of energy transport in experiments on “atomic giants”

By realising an artificial quantum system, physicists at Heidelberg University have simulated key processes of photosynthesis on a quantum level with high spatial and temporal resolution. In their experiment with Rydberg atoms the team of Prof. Dr. Matthias Weidemüller and Dr. Shannon Whitlock discovered new properties of energy transport.


Dipole-mediated energy transport of Rydberg-excitations (glowing balls) in an atomic sea – artist impression

Picture credits: S. Whitlock / G. Günter

This work is an important step towards answering the question of how quantum physics can contribute to the efficiency of energy conversion in synthetic systems, for example in photovoltaics. The new discoveries, which were made at the Center for Quantum Dynamics and the Institute for Physics of Heidelberg University, have now been published in the journal “Science”.

In their research, Prof. Weidemüller and his team begin with the question of how the energy of light can be efficiently collected and converted elsewhere into a different form, e.g. into chemical or electric energy. Nature has found an especially efficient way to accomplish this in photosynthesis. Light energy is initially absorbed in light-harvesting complexes – an array of membrane proteins – and then transported to a molecular reaction centre by means of structures called nanoantennae; in the reaction centre the light is subsequently transformed into chemical energy. “This process is nearly 100 per cent efficient. Despite intensive research we’re still at a loss to understand which mechanisms are responsible for this surprisingly high efficiency,” says Prof. Weidemüller. Based on the latest research, scientists assume that quantum effects like entanglement, where spatially separated objects influence one another, play an important role.

In their experiments the researchers used a gas of atoms that was cooled down to a temperature near absolute zero. Some of the atoms were excited with laser light to high electric states. The excited electron of these “atomic giants”, which are called Rydberg atoms, is separated by macroscopic distances of almost a hair’s breadth from the atomic nucleus. Therefore these atoms present an ideal system to study phenomena at the transition between the macroscopic, classical world and the microscopic quantum realm. Similar to the light-harvesting complexes of photosynthesis, energy is transported from Rydberg atom to Rydberg atom, with each atom transmitting its energy packages to surrounding atoms, similar to a radio transmitter.

“To be able to observe the energy transport we first had to find a way to image the Rydberg atoms. At the time it was impossible to detect these atoms using a microscope,” explains Georg Günter, a doctoral student in Prof. Weidemüller’s team. A trick from quantum optics ensured that up to 50 atoms within a characteristic radius around a Rydberg atom were able to absorb laser light. In this way each Rydberg atom creates a tiny shadow in the microscope image, allowing the scientists to measure the positions of the Rydberg atoms.

The fact that this technique would also facilitate the observation of energy transport came as a surprise, as PhD student Hanna Schempp emphasises. However, the investigations with the “atomic giants” showed how the Rydberg excitations, which are immersed in a sea of atoms, diffused from their original positions to their atomic neighbours, similar to the spreading of ink in water. Aided by a mathematical model the team of Prof. Weidemüller showed that the atomic sea crucially influences the energy transport from Rydberg atom to Rydberg atom.

“Now we are in a good position to control the quantum system and to study the transition from diffusive transport to coherent quantum transport. In this special form of energy transport the energy is not localised to one atom but is distributed over many atoms at the same time,” explains Prof. Weidemüller. As with the light-harvesting complexes of photosynthesis, one central question will be how the environment of the nanoantennae influences the efficiency of energy transport and whether this efficiency can be enhanced by exploiting quantum effects. “In this way we hope to gain new insights into how the transformation of energy can be optimised in other synthetic systems as well, like those used in photovoltaics,” the Heidelberg physicist points out.

Online information:
Research group of Prof. Weidemüller: http://www.physi.uni-heidelberg.de/Forschung/QD
Center for Quantum Dynamics: http://cqd.uni-hd.de
Institute for Physics: http://www.physi.uni-heidelberg.de/?lang=en
Original publication:
G. Günter, H. Schempp, M. Robert-de-Saint-Vincent, V. Gavryusev, S. Helmrich, C.S. Hofmann, S. Whitlock, M. Weidemüller: Observing the Dynamics of Dipole-Mediated Energy Transport by Interaction Enhanced Imaging, Science Express (7 November 2013), doi: 10.1126/science.1244843
Contact:
Prof. Dr. Matthias Weidemüller
Institute for Physics / Center for Quantum Dynamics
Phone +49 6221 54-19471, -19470 (secretary’s office)
weidemueller@uni-heidelberg.de
Communications and Marketing
Press Office, phone: +49 6221 54-2311
presse@rektorat.uni-heidelberg.de

Marietta Fuhrmann-Koch | idw
Further information:
http://www.uni-heidelberg.de

More articles from Physics and Astronomy:

nachricht Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>