Entangling photons with the help of local dissipation
Prof. Dr. Dagmar Bruß (Institut für Theoretische Physik III, Universität Düsseldorf)

We show that, counterintuitively, local dissipation allows to entangle two photons, in a scenario where otherwise no entanglement can be present, in spite of employing non-local interactions via a CNOT gate.
This phenomenon is due to some subtle features of the quantum world: a local non-unital channel (such as dissipation) can turn classical correlations into quantum correlations. These quantum correlations can then be activated into entanglement via a CNOT gate. We experimentally demonstrate this effect with hyperentangled photons and show that the created amount of entanglement is proportional to the amount of dissipative noise, see Phys. Rev. Lett. 115, 160503 (2015).
In our four-qubit experiment the generated entanglement is robust against local unitaries performed by an adversary.
- Joint work with A. Orieux(2,3), M. Ciampini(2), P. Mataloni(2), M. Rossi(4) and C. Macchiavello(4).
(2) Dipartimento di Fisica, Sapienza Università di Roma, Italy (3) Dipartimento Télécom ParisTech, CNRS-LTCI, Paris, France (4) Dipartimento di Fisica and INFN, Pavia, Italy