Project: SECuRe quantum communication based on Energy-Time/time-bin entanglement

Acronym	SECRET
Project Topic	Quantum communications (QC) is one of the main areas of the broader field of Quantum Technologies. The most well-known application of QC is in communication security, where huge progress has been observed since the first demonstrations of quantum key distribution (QKD). Another important application of QC is as the support backbone for future networks of quantum computers, the so-called Quantum Internet. Entanglement is a crucial resource in both applications. It allows a higher level of security in QKD, as well as being a requirement in many Quantum Internet communication protocols. Therefore it is very important to ensure that entanglement can be certified, and a very popular way to do it is through a Bell inequality violation. A particularly important type of photonic entanglement is called energy-time (ET). It has been very popular over the last 25 years or so, since it is very robust against disturbances that affect other types of entanglement over optical fibers. The downside has been that most experimental implementations employ the famous “Franson’s configuration”, which has an inherent flaw called the post-selection loophole that invalidates a Bell inequality violation, unless extra assumptions are present. All members of this consortium have been responsible for proposing and carrying out the first, and so far only performed, QC experiments based on ET (and its pulsed version called time-bin) entanglement that do not present the post-selection flaw, and thus can be used to perform experiments based on “genuine” ET/time-bin entanglement. This project now aims to carry out the first generation of genuine energy-time/time-bin experiments aimed at final, practical applications. We intend to perform, based on this type of entanglement the first: (i) QKD experiments and (ii) entanglement swapping/teleportation experiments. Furthermore, our project will also perform the first implementations of QKD with genuine energy-time/time-bin entanglement on integrated photonic circuits, as well as strong theoretical analysis on the post-selection loophole in these new experiments. The results proposed will form an important experimental and theoretical framework to support the future development of the Quantum Internet based on the telecommunication optical fibre network. This project includes elements from two areas of target outcomes as specified in the QuantERA 2019 call. Quantum communication is of course the main area as an outcome due to the proposed experiments aimed at executing QKD and entanglement swapping based on genuine energy-time entanglement. A secondary target outcome area is Quantum information sciences, since we will also work on the optimization of Bell inequality violations aiming at communication security. Of the Expected impacts, as listed on the call, our project broadly touches most of them. More specifically though, its direct impacts include the (i) development of reliable technologies for different components of quantum architectures…, (ii) develop a deeper fundamental and practical understanding of systems and protocols… and (iii) enhance the robustness and scalability of quantum information technologies in the presence of environmental decoherence.
Network	QuantERA
Call	QuantERA Call 2019

Project partner

Number	Name	Role	Country
1	Linköping University	Coordinator	Sweden
2	Universidad de Sevilla	Partner	Spain
3	Istituto Nazionale di Fisica Nucleare - INFN	Partner	Italy