Recent News

Quantum entanglement between 16 million atoms in a solid

Quantum theory is unequivocal: it predicts that a vast number of atoms can be entangled and intertwined by a very strong quantum relationship even in a macroscopic structure. Until now, however, experimental evidence has been mostly lacking, although recent advances have shown the entanglement of 2,900 atoms. Our group together with Prof. Nicolas Brunner have recently demonstrated the entanglement between 16 million atoms in a crystal. This was done based on the novel theoretical approach of certifying geniune multipartite entanglement for multiatomic ensembles interacting with light. The research is published in Nature Communications while the brief explanation of main results can be found in the University press realease.

In a parallel work by groups of Prof. Christoph Simon and Prof. Wolfgang Tittel from University of Calgary an entanglement between many large groups of atoms has been demonstrated.


 

Multimode generation of quantum correlated photons using a crystal

The ability to distribute entanglement over long distances could be a key-enabling technology that will allow the large-scale deployment of quantum technologies. In our recent article published in Physical Review Letter and featured in Physics, we demonstrated an important step towards implementing a quantum repeater. Using our Europium doped crystal we produced streams of biphotons with one of the photon delayed up to 1 ms. This work shows that rare-earth crystals can be used to generate long-lived quantum correlations between spins and single photons, with a unique ability of temporal multiplexing that is important for increasing the speed of future quantum repeaters.



 

Quantifying high-dimensional entanglement with photons

Our paper demonstrating high-dimensional entanglement of photonics states was published in Physical Review Letters. We experimentally apply a new procedure for entanglement certification that is suitable for different physical systems. The method we developed is based on entanglement formation and allowed us to certify 4 bits of entanglement (or ebits) shared between two photons.

This work was done in collaboration with Nicolas Brunner from Geneva and Marcus Huber from Vienna.

 

Emerging Talents: Florian Fröwis

The Editorial Board of Journal of Physics A has selected Florian Fröwis to contribute to the special issue: Emerging Talents as part of the Journal of Physics series’ 50th anniversary celebrations in 2017. His paper “Lower bounds on the size of general Schrödinger-cat states from experimental data” was now published in this special issue.