Experimental violation of n-locality in a star quantum network

The launch of a satellite capable of distributing entanglement through long distances and the first loophole-free violation of Bell inequalities are milestones indicating a clear path for the establishment of quantum networks. However, nonlocality in networks with independent entanglement sources has only been experimentally verified in simple tripartite networks, via the violation of bilocality inequalities. Here, by using a scalable photonic platform, we implement star-shaped quantum networks consisting of up to five distant nodes and four independent entanglement sources. We exploit this platform to violate the chained n-locality inequality and thus witness, in a device-independent way, the emergence of nonlocal correlations among the nodes of the implemented networks. These results open new perspectives for quantum information processing applications in the relevant regime where the observed correlations are compatible with standard local hidden variable models but are non-classical if the independence of the sources is taken into account.

Davide Poderini, Iris Agresti, Guglielmo Marchese, Emanuele Polino, Taira Giordani, Alessia Suprano, Mauro Valeri, Giorgio Milani, Nicolò Spagnolo, Gonzalo Carvacho, Rafael Chaves and Fabio Sciarrino. Nature Communications 11, 2467 (2020) Published: 18 May 2020

Link: https://www.nature.com/articles/s41467-020-16189-6

Machine Learning-Based Classification of Vector Vortex Beams

Structured light is attracting significant attention for its diverse applications in both classical and quantum optics. The so-called vector vortex beams display peculiar properties in both contexts due to the nontrivial correlations between optical polarization and orbital angular momentum. Here we demonstrate a new, flexible experimental approach to the classification of vortex vector beams. We … Continua a leggere

Experimental quantification of four-photon indistinguishability

Photon indistinguishability plays a fundamental role in information processing, with applications such as linear-optical quantum computation and metrology. It is then necessary to develop appropriate tools to quantify the amount of this resource in a multiparticle scenario. Here we report a four-photon experiment in a linear-optical interferometer designed to simultaneously estimate the degree of indistinguishability … Continua a leggere

Advice on Coronavirus

Sapienza University of Rome, to preserve the university community’s health, is implementing protective measures issued by the Italian Health Authorities against the COVID-19. Services and educational activities have not been suspended Sapienza University of Rome, to preserve the university community’s health, is implementing the protective measures issued by the Italian Health Authorities against the COVID-19. … Continua a leggere

Congratulations to Iris, Taira and Emanuele for their PhD thesis defense!

On 7th of February 2020, Iris, Taira and Emauele have successfully defended their PhD theses under the supervision of Prof. Fabio Sciarrino. Iris discussed her PhD project regarding the “Certification of quantum technologies”. Taira’s thesis was entitled “Photonics quantum walks as test-bed learning protocols” while Emanuele discussed ” Photonic technologies for fundamental tests of quantum … Continua a leggere

SEMINAR: Quantum computing and its applications in chemistry and physics – Dr.Ivano Tavernelli (IBM Research-Zurich)

Aula Conversi (Dipartimento di Fisica – Ed. G. Marconi) Tuesday 14 January 2020, 16:00 → 18:00 Sapienza Università di Roma. In this talk, we will first introduce the basics of quantum computing using superconducting qubits, focusing on those aspects that are crucial for the implementation of quantum chemistry algorithms. In the second part, I will … Continua a leggere

Interfacing scalable photonic platforms: solid-state based multi-photon interference in a reconfigurable glass chip

Scaling-up optical quantum technologies requires a combination of highly efficient multi-photon sources and integrated waveguide components. Here, we interface these scalable platforms, demonstrating high-rate three-photon interference with a quantum dot based multi-photon source and a reconfigurable photonic chip on glass. We actively demultiplex the temporal train of single photons obtained from a quantum emitter to … Continua a leggere