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Twin Atoms: A New Source for Entangled Particles

Jülich, 8 March 2021 – Quantum stunts that could previously only be realised with photons are now also becoming possible with atoms: scientists at Forschungszentrum Jülich, together with partners at TU Wien, have succeeded in producing quantum entangled atomic beams.

Heads or tails? When we toss two coins in the air, the result of one coin toss has nothing to do with the result of the other. But in the world of quantum physics, things are different: quantum particles can be entangled. In that case, they can only be described together.

For years now, there have been different methods to produce entangled photons. For example, special crystals can be used to convert a photon with high energy into two photons with lower energy - this is called "down conversion". With this technique, large numbers of entangled photon pairs can be produced quickly and easily.

Interview with Tommaso Calarco

In an interview, quantum physicist Tommaso Calarco talks about the opportunities opened up by the new method for producing entangled atomic beams.

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However, entangling atoms is much more difficult. Previous approaches have focused on entangling individual pairs of atoms using complicated laser operations. Or random chance has been given the reigns to produce quantum entanglements: for example, by breaking molecules so that entangled fractions fly away.

Using a new technique, researchers at TU Wien have now succeeded in creating large numbers of entangled atom pairs in a controlled manner: a cloud of ultracold atoms is held in place by electromagnetic forces on a tiny chip. The atoms are manipulated in such a way that they do not assume the state with the lowest possible energy, also known as Bose-Einstein condensate, but the next highest energy state. This was made possible by a collaboration with Professor Tommaso Calarco's group at Forschungszentrum Jülich, who developed a quantum control technique to excite the Bose-Einstein condensate in the trap.

This electromagnetic trap is constructed in such a way that the return to the ground state is physically impossible for a single atom. The atoms can only change back in pairs and then fly away in opposite directions. This creates entangled twin atoms that move exactly in the direction specified by the electromagnetic trap on the chip.

AtomchipThe atom chip used for the quantum experiments
Copyright: TU Wien

Original publication:

F. Borselli, M. Maiwöger, T. Zhang, P. Haslinger, V. Mukherjee, A. Negretti, S. Montangero, T. Calarco, I. Mazets, M. Bonneau, J. Schmiedmayer
Two-Particle Interference with Double Twin-Atom Beams
Phys. Rev. Lett. (2021), DOI: 10.1103/PhysRevLett.126.083603

Further informationen:

Synpsis in Physics of 23 February 2021

Press release, TU Wien, 24 February 2021

Peter Grünberg Institute, Quantum Control (PGI-8)

Contact:

Prof. Dr. Tommaso Calarco
Head of Peter Grünberg Institute, Quantum Control (PGI-8)
Tel: +49 2461 61-9365
E-mail: t.calarco@fz-juelich.de

Press contact:

Tobias Schlößer
Corporate Communications
Tel: +49 2461 61-4771
E-mail: t.schloesser@fz-juelich.de