Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental buildi...Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental building block toward quantum networks.Among the different degrees of freedom,orbital angular momentum(OAM)is one of the most promising due to its natural capability to encode high dimensional quantum states.We experimentally demonstrate fiber distribution of hybrid polarization-vector vortex entangled photon pairs.To this end,we exploit a recently developed air-core fiber that supports OAM modes.High fidelity distribution of the entangled states is demonstrated by performing quantum state tomography in the polarization-OAM Hilbert space after fiber propagation and by violations of Bell inequalities and multipartite entanglement tests.The results open new scenarios for quantum applications where correlated complex states can be transmitted by exploiting the vectorial nature of light.展开更多
Multicore fibers are expected to be a game-changer in the coming decades thanks to their intrinsic properties,allowing a larger transmission bandwidth and a lower footprint in optical communications.In addition,multic...Multicore fibers are expected to be a game-changer in the coming decades thanks to their intrinsic properties,allowing a larger transmission bandwidth and a lower footprint in optical communications.In addition,multicore fibers have recently been explored for quantum communication,attesting to their uniqueness in transporting high-dimensional quantum states.However,investigations and experiments reported in literature have been carried out in research laboratories,typically making use of short fiber links in controlled environments.Thus,the possibility of using long-distance multicore fibers for quantum applications is still to be proven.We characterize here for the first time,to the best of our knowledge,in terms of phase stability,multiple strands of a four-core multicore fiber installed underground in the city of L’Aquila,with an overall fiber length up to about 25 km.In this preliminary study,we investigate the possibility of using such an infrastructure to implement quantumenhanced schemes,such as high-dimensional quantum key distribution,quantum-based environmental sensors,and more,in general,quantum communication protocols.展开更多
基金P.Kristensen from OFS-Fitel for the fiber fabrication,and D.Poderini for many advices on the software development.Funding Information:This work was supported by the Center of Excellence,SPOC-Silicon Photonics for Optical Communications(ref DNRF123)by the People Programme(Marie Curie Actions)of the European Union’s Seventh Framework Programme(FP7/2007-2013)under REA grant agreement no.609405(COFUNDPostdocDTU)+1 种基金and by the ERC-Advanced grant PHOSPhOR(Photonics of Spin-Orbit Optical PhenomenaGrant Agreement No.694683).G.C.acknowledges Becas Chile and Conicyt.
文摘Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication.Distribution of photonic entangled states using optical fiber links is a fundamental building block toward quantum networks.Among the different degrees of freedom,orbital angular momentum(OAM)is one of the most promising due to its natural capability to encode high dimensional quantum states.We experimentally demonstrate fiber distribution of hybrid polarization-vector vortex entangled photon pairs.To this end,we exploit a recently developed air-core fiber that supports OAM modes.High fidelity distribution of the entangled states is demonstrated by performing quantum state tomography in the polarization-OAM Hilbert space after fiber propagation and by violations of Bell inequalities and multipartite entanglement tests.The results open new scenarios for quantum applications where correlated complex states can be transmitted by exploiting the vectorial nature of light.
基金orizon 2020 Framework Programme OpenQKD(857156),SQUARE(731473)Ministero dell’Istruzione,dell’Universitàe della Ricerca(INCIPIT)+1 种基金H2020 Science with and for Society(G5485)Danmarks Grundforskningsfond SPOC(123).
文摘Multicore fibers are expected to be a game-changer in the coming decades thanks to their intrinsic properties,allowing a larger transmission bandwidth and a lower footprint in optical communications.In addition,multicore fibers have recently been explored for quantum communication,attesting to their uniqueness in transporting high-dimensional quantum states.However,investigations and experiments reported in literature have been carried out in research laboratories,typically making use of short fiber links in controlled environments.Thus,the possibility of using long-distance multicore fibers for quantum applications is still to be proven.We characterize here for the first time,to the best of our knowledge,in terms of phase stability,multiple strands of a four-core multicore fiber installed underground in the city of L’Aquila,with an overall fiber length up to about 25 km.In this preliminary study,we investigate the possibility of using such an infrastructure to implement quantumenhanced schemes,such as high-dimensional quantum key distribution,quantum-based environmental sensors,and more,in general,quantum communication protocols.
