The security of modern communication networks can be enhanced thanks to the laws of quantum mechanics. In this thesis, we develop a source of photon-pairs, emitted via spontaneous parametric down-conversion, which we use to demonstrate new quantum-cryptographic primitives. Pairs are used as heralded single-photons or as close-to-maximally entangled pairs. We also provide a novel design in order to adapt this source to multipartite entanglement generation. We provide the first experimental implementation of quantum weak coin flipping protocol. It allows two distant players to decide of a random winner. We demonstrate a refined and loss-tolerent version of a recently proposed theoretical protocol, using heralded single-photons mixed with vacuum to produce entanglement. It displays cheat-sensitivity, allowed by quantum interference and a fast optical switch. We also provide a new protocol for certifying the transmission of an unmeasured qubit through a lossy and untrusted channel. The security is based on new fundamental results of lossy quantum channels. We device-independently test the channel’s quality, using self-testing of Bell or steering inequalities thanks to photon-pairs entangled in polarization to probe the channel. We show it allows the certification of quantum communication for a large amount of losses induced by the channel.
The security of modern communication networks can be enhanced thanks to the laws of quantum mechanics. In this thesis, we develop a source of photon-pairs, emitted via spontaneous parametric down-conversion, which we use to demonstrate new quantum-cryptographic primitives. Pairs are used as heralded single-photons or as close-to-maximally entangled pairs. We also provide a novel design in order to adapt this source to multipartite entanglement generation. We provide the first experimental implementation of quantum weak coin flipping protocol. It allows two distant players to decide of a random winner. We demonstrate a refined and loss-tolerent version of a recently proposed theoretical protocol, using heralded single-photons mixed with vacuum to produce entanglement. It displays cheat-sensitivity, allowed by quantum interference and a fast optical switch. We also provide a new protocol for certifying the transmission of an unmeasured qubit through a lossy and untrusted channel. The security is based on new fundamental results of lossy quantum channels. We device-independently test the channel’s quality, using self-testing of Bell or steering inequalities thanks to photon-pairs entangled in polarization to probe the channel. We show it allows the certification of quantum communication for a large amount of losses induced by the channel.