QUROPE Quantum Information Processing and Communication in Europe

A participatory workshop on Quantum Technologies and Industry was held in Brussels on 6 May 2015. The aim was to identify what could be the markets for quantum technologies, and how these could be industrialised. The workshop report (available here) summarises the discussions and the action plan which emerged as a conclusion.

We report on the direct measurement in real space of the effect of the van der Waals forces between individual Rydberg atoms on their external degrees of freedom. Clusters of Rydberg atoms with inter-particle distances of around 5 {\mu}m are created by first generating a small number of seed excitations in a magneto-optical trap, followed by off-resonant excitation that leads to a chain of facilitated excitation events. After a variable expansion time the Rydberg atoms are field ionized, and from the arrival time distributions the size of the Rydberg cluster after expansion is calculated.

Displaced single-photon entanglement is a simple form of optical entanglement, obtained by sending a photon on a beam splitter and subsequently applying a displacement operation. We show that it can generate, through a momentum transfer in the pulsed regime, an optomechanical entangled state involving macroscopically distinct mechanical components, even if the optomechanical system operates in the singlephoton weak coupling regime. We discuss the experimental feasibility of this approach and show that it might open up a way for testing unconventional decoherence models

Single-photon entanglement is one of the primary resources for quantum networks, including quantum repeater architectures. Such entanglement can be revealed with only local homodyne measurements through the entanglement witness presented in Morin et al (2013 Phys. Rev. Lett. 110 130401). Here, we provide an extended analysis of this witness by introducing analytical bounds and by reporting measurements confirming its great robustness with regard to losses.

What is the most efficient way to generate random numbers device-independently using a photon pair source based on spontaneous parametric down conversion? We consider this question by comparing two implementations of a detection-loophole-free Bell test. In particular, we study in detail a scenario where a source is used to herald path-entangled states, i.e.

We study the operation of linear optics schemes for entanglement distribution based on nonlocal photon subtraction when input states, produced by imperfect single-photon sources, exhibit both vacuum and multiphoton contributions. Two models for realistic photon statistics with radically different properties of the multiphoton “tail” are considered. The first model assumes occasional emission of double photons and linear attenuation, while the second one is motivated by heralded sources utilizing spontaneous parametric down-conversion.

How can one detect entanglement between multiple optical paths sharing a single photon? We address this question by proposing a scalable protocol, which only uses local measurements where single photon detection is combined with small displacement operations. The resulting entanglement witness does not require postselection, nor assumptions about the photon number in each path. Furthermore, it guarantees that entanglement lies in a subspace with at most one photon per optical path and reveals genuinely multipartite entanglement.

The on-line version of the document can be browsed here,
a pdf of the full document will be generated following this link.

IOP Physics World informs that The European Physical Society (EPS) has hit out at plans to remove €2.7bn from the €80bn budget of Horizon 2020 – the European Union's main research funding programme – and use the money instead to help finance a new European Union economic-stimulus initiative.

Read the full article here.

In the Work Programme 2014-2015, FET Proactive consists of 3 initiatives under the "Emerging themes and communities" call, and for a fourth one, under the dedicated "Towards exascale high-performance computing" call, implementing part of the HPC strategy elaborated in the context of the HPC Public-Private Partnership by ETP4HPC.

Emerging Themes and Communities

Following a public consultation during 2012-2013, 'Quantum simulation' was one of the three topics that have been selected for inclusion in the 2014-15 work programme.