Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum-tweaking of single photons

14.07.2009
Physicists at MPQ control quantum interference by tuning the phase of single photons.

Precise control of quantum effects is vital to the realization of entirely new technologies. For example, a computer based on quantum physical principles is expected to outperform today's classical computers.

In communication technology, quantum devices are already commercially available which allow secure transmission of data. Controlling the properties of photons down to the quantum level is at the heart of these technologies. In recent years, scientists in the group of Prof. Gerhard Rempe, Director at the Max Planck Institute of Quantum Optics (MPQ) in Garching, have managed to control the shape, frequency and polarization of single photons.

However, only now have they been able to also tune the phase of single photons, as they report in Nature Photonics (Advanced Online Publication, DOI: 10.1038 /NPHOTON.2009.115, 13 July 2009). While offering new applications in quantum information technologies, these results are also of fundamental importance for understanding the quantum behavior of light.

The phase of a classical electromagnetic wave describes the state of the electric field during its oscillation cycle. It can usually be measured very precisely. However, at extremely low light intensities this is no longer true as the quantum properties of light come into play. Ultimately, Heisenberg's uncertainty principle even prevents ascribing a phase to a single photon - but the issue has its subtleties. In their pioneering experiment, the physicists at MPQ have shown that a classical phase shift applied during the propagation of a single photon also changes the quantum properties of the photon.

Key to these new results is the reliable generation of single photons at the push of a button. For this, the team used a single rubidium atom trapped in an optical micro resonator. When the atom was repeatedly excited by appropriate laser pulses, it emitted one single photon after the other. As seen in the figure, two photons are sent onto a semi-transparent mirror (i.e. beam splitter) such that they simultaneously impinge on its two input ports.

The beam splitter used in the experiments distributes the incoming light of the two inputs in equal amounts to both output ports. A classical particle would choose one of the two outputs with equal probability. Consequently, for two classical particles arriving at the beam splitter simultaneously, the probability to detect both at the same output is just as high as the probability to find them at two different output ports. At the quantum level, the situation is dramatically different: Due to their bosonic nature, identical single photons are forced to always take the same output port. This "quantum interference" effect has first been demonstrated in 1987 and is a cornerstone of modern quantum optics.

Now, the team of Prof. Rempe has built on this quantum interference and in their recent experiment they showed that it can be controlled and even inverted by tweaking the phase of one of the photons. After the detection of the first photon, a user-selected phase shift can be used to deliberately determine the path of the second photon. A subclass of the measurements revealed the possibility to guide the photons to two different output ports - a behavior that is usually attributed to fermions.

These measurements show that with regard to a complete characterization of a photon, the phase must also be taken into account. Combined with previously demonstrated control of a photon's amplitude, frequency and polarization, the fully deterministic phase shaping presented here allows for the complete control of single photon wave packets. These results are a further step on the way to realize quantum computers on the basis of atoms and photons, and could also be used for establishing new quantum communication protocols.

Olivia Meyer-Streng

Original publication:
Phase shaping of single-photon wave packets
H. P. Specht, J. Bochmann, M. Mücke, B. Weber, E. Figueroa, D.L. Moehring and G. Rempe

Nature Photonics, Advance Online Publication, DOI: 10.1038/NPHOTON.2009.115

Contact:
Prof. Dr. Gerhard Rempe
Max Planck Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching
Phone: +49 - 89 / 32905 - 701
Fax: +49 - 89 / 32905 - 311
E-mail: gerhard.rempe@mpq.mpg.de
Holger Specht
Quantum Dynamics Division
Max Planck Institute of Quantum Optics
Phone: +49 - 89 / 32905 - 333
E-mail: holger.specht@mpq.mpg.de
Dr. Olivia Meyer-Streng
Press & Public Relations
Max Planck Institute of Quantum Optics
Phone: +49 - 89 / 32905 - 213
E-mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | idw
Further information:
http://www.mpq.mpg.de

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>