A quantum system of 20 meters in size
Munich, July 6, 2012
Quantum effects like superposition and entanglement usually appear at smallest scales in the microcosm and contradict our everyday experience. However, observing these effects is experimentally challenging and usually restricted to simple microscopic objects like atoms and small organic molecules in a well-isolated environment.
A research group led by Harald Weinfurter from LMU Munich and MPI of Quantum Optics at Garching pursues a completely different path. Instead of trying to isolate a single quantum system and to preserve its quantum properties, a macroscopic quantum object is "constructed" from two microscopic ones which are widely separated.
The researchers start with two single atoms which are independently trapped in two laboratories 20 meters apart. The atoms are excited via short optical laser pulses thereby emitting single photons. These photons are then brought together via optical fibers to an intermediate location and interfere on a beam splitter. The two-fold detection of the photons behind the beam splitter then projects the atoms onto an entangled state.
One important property of this method is that the registration of the two photons reports (heralds) the successful entanglement preparation to the experimenter. "Therefore it is not necessary to verify the result at every attempt as such verification destroys the quantum state", says Weinfurter. This new quantum system opens up perspectives for future quantum-communication applications as well as important tests on the foundations of quantum physics.
Publication:
Julian Hofmann, Michael Krug, Norbert Ortegel, Lea Gérard, Markus Weber, Wenjamin Rosenfeld und Harald Weinfurter Heralded
Entanglement Between Widely Separated Atoms Science, vol. 337, p. 72, 6 July 2012; DOI:10.1126/science.1221856
Contact:
Professor Harald Weinfurter
LMU Munich
Faculty of Physics
Schellingstraße 4/III
80799 München
Germany
Phone: +49 (0)89 2180-2044
Fax: +49 (0)89 2180-5032
Email:harald.weinfurter@physik.uni-muenchen.de
Dr. Markus Weber
LMU Munich
Faculty of Physics
Schellingstraße 4/III
80799 München
Germany
Phone: +49 (0)89 2180-2045
Email: markusweber@lmu.de
Dr. Wenjamin Rosenfeld
LMU Munich
Faculty of Physics
Schellingstr. 4/III
80799 München
Germany
Phone: +49 (0)89 2180-2045
Email: Wenjamin.Rosenfeld@physik.uni-muenchen.de