Transnational Projects

We bring together researchers on quantum information theory, BoseEinstein condensates and atom interferometry to create, detect and exploit Einstein-Podolsky-Rosen and Beli entanglement in atomic BoseEinstein condensates. These represent much stronger forms of entanglement than the non-classical correlations created so far and are largely unexplored. Our purpose is both to gain a deeper understanding of quantum information in many body systems as well as to develop practical approaches for manipulating and exploiting it. The main targets are (i) to take advantage of this type of quantum correlation, (ii) to implement device-independent entanglement witnesses, (iii) to explore fundamental aspects of quantum mechanics, and (iv) to realize proof-of-principle implementations of quantum information and quantum measurement protocols with atomic many-body systems.

Atomic interactions in BEC's constitute a non-linearity highly analogous to four-wave mixing or parametric down-conversion in optics, and hence can create strong entanglement. Two separate lines of research have been pursued in the past; on the one hand, one can use the spin degrees of freedom of an atom to produce atom pairs whose spins are entangled, and on the other hand one can entangle the motional degrees of freedom in a spirit close to that of the originai EPR proposal. In the CEBBEC project, these two lines of research will be brought together in both the technological sense (using one kind of entanglement to make another) and conceptual one (for example studying complex situations in which both spin and motion are entangled) giving rise to new possibilities for applications and new theoretical challenges. The participating partners have developed sophisticated detection technologies which allow us to make new types of measurements. We intend to respond to the great need for theoretical work to understand and exploit them. Finally, we will address practical applications and explore their metrological validity.

CONSORTIUM
Coordinator: Christoph Westbrook, lnstitute of Optics, Charles Fabry Laboratory, France
Carsten Klempt, lnstitute of Quantum Optics, Leibniz University of Hannover, Germany
Marie Bonneau, Technical University ofWien, Austria
Géza Tóth, University of the Basque Country, Spain
Augusto Smerzi, National Research Council (CNR), ltaly

Today, photonics is among the very few platforms that can reach very high levels of complexity in quantum communication, computation and sensing. This is made possible by the mobility of photons and the large variety of their controllable degrees of freedom. The quantum optics community has already obtained spectacular achievements, yet using quite inefficient sources and bulk optics, limiting the number of particles involved, the explored Hilbert space dimension and the fidelity of the protocols.

Very recently, a new generation of single-photon sources and high complexity integrated optical circuits have emerged, promising to drastically scale up quantum optical technologies. In this project, experts in solid-state single-photon sources, integrated photonics, quantum optics and complexity theory join their expertise to develop a whole new platform to perform high-fidelity quantum protocols, involving a large number of particles (>8) and large number of modes (>40) in high-dimensional Hilbertspaces (108).

We will develop near-optimal single-photon sources based on semiconductor quantum dots, and couple them to highly reconfigurable two- and three-dimensional photonic glass chips to implement multiphoton multi-mode quantum walks. With this new platform, we will implement high photonnumber Boson sampling measurements, develop new certification protocols and head toward the threshold for quantum advantage. The platform will also be used to demonstrate new secure quantum computation schemes such as homomorphic encryption, and quantum communication tasks based on so-called quantum enigma machines. The richness of applications for our developed photonic platform will be further demonstrated by new advanced metrology tasks that enable simultaneous multiparameterestimation. Our interdisciplinary consortium and work methodology gives us the ideal condition to tackle these challenges and thus to establish a new generation of photonic quantum platforms.

CONSORTIUM
Coordinator: Pascale Senellart, National Center for Scientific Research (CNRS), France
Philip Walther, University of Vienna, Austria
Roberto Osellame and Fabio Sciarrino, National Research Council (CNR), ltaly
lan Walmsley, University of Oxford, United Kingdom
Mario Ziman, lnstitute of Physics, Slovak Academy of Sciences, Slovakia

In a quantum simulator, the time evolution of a quantum system should be controlled to reach the desired outcome of the simulation. Quantum simulators, more precisely quantum annealers, start to appear in the market (at very prohibitive prices for an individual person) but an efficient manipulation of such systems still requires fundamental progress in our basic understanding of quantum systems. First, the dynamics of a quantum system in which many particles interact altogether is a complex problem. Second, quantum simulators are often facing the presence of phase transitions during their time evolution which makes their control difficult.

In our consortium we gather theoreticians with a large expertise in out-of-equilibrium dynamics of quantum many-body systems and in the physics of phase transitions together with experimentalist studying these problems with ultracold quantum gases. Quantum gases are unlikely to be a platform for commercial simulators but they are ideal test systems which are well-controlled and tunable. We will explore in this project the dynamics of quantum systems around phase transitions in synergy between state-of-the-art experiments and computational tools to provide a comprehensive picture of this subject that could be applied to quantum simulators prototypes in the next future.

CONSORTIUM
Coordinator: Jérome Beugnon, Kastler Brossel Laboratory, France
Giovanna Morigi, Saarland University, Germany
Gabriele Ferrari, National lnstitute of Optics, National Research Council (INO-CNR), ltaly
Jacek Dziarmaga, Jagiellonian University, Poland
Zoran Hadzibabic, University of Cambridge, United Kingdom
Nikolaos Proukakis, University of Newcastle, United Kingdom
Tilman Esslinger, Swiss Federai lnstitute ofTechnology, Switzerland

Scientific Officer Contacts:
Gabriele Ferrari
INO-CNR BEC Center
Physics Department, University of Trento
Address: Via Sommarive 14, I-38123 Povo, Italy
Lab: +39-0461-2853 -35 -27
Office: +39-0461-285333
Email: gabriele.ferrari@ino.it

Our society relies on secure communication, powerful computers and precise sensors. Basic science has shown that huge improvements in these capabilities are possible if we can utilise many single quantum objects working in concert. We can then see how to store and process huge amounts of information in a fully secure way and how to make exquisitely sensitive measurements of fields and forces.

Specific types of quanta - photons, electrons, phonons - already bring new specific functions, but to realise the full promise of quantum technologies, it will be necessary to interface these systems with each other in a way that is practical and scalable. This is the focus of our programme. ORQUID will explore the exciting new possibility of using single organic molecules as the interface between these three quanta so that they can work together as required. First, single molecules will interact with light in waveguides and cavities to generate and detect single photons, providing immediate impact in quantum photonics. Second, single molecules will detect single moving charges in nano-electronic circuits to provide quantum coherent information exchange between these charges and the external world. Third, molecules embedded in nanomechanical devices and twodimensional materials will measure nanoscale forces and displacements, which are key to developing mechanical quantum systems and understanding nanomachinery. By developing these three interfaces on a common platform, we will create a versatile hybrid system. By allowing the user to draw simultaneously on the most sensitive quantum aspects of light, chargé and sound, we anticipate that this hybrid will be a major advance in the technology of quantum devices.

CONSORTIUM
Coordinator: Costanza Toninelli, National Research Council (CNR), ltaly
Wolfram Pernice, University of Munster, Germany
Frank Koppens, lnstitute of Photonic Sciences, Spain
André Gourdon, National Center for Scientific Research (CNRS), France
Michel Orrit, Leiden University, Netherlands
Boleslaw Kozankiewicz, lnstitute of Physics, Polish Academy of Sciences, Poland
Edward Hinds, Imperial College of Science Technology and Medicine, United Kingdom

Scientific Officer Contacts:
Costanza Toninelli
National lnstitute of Optics, National Research Council (INO-CNR)
Office: +39 055 457 2134
Lab: +39 055 457 2389
Email: costanza.toninelli@ino.it

The "Atomic Quantum Clock" is a milestone of the European Quantum Technologies Timeline. Q-Clocks seeks to establish a new frontier in the quantum measurement of time by joining state-of-the-art optical lattice clocks and the quantized electromagnetic field provided by an optical cavity. The goal of the project is to apply advanced quantum techniques to state-of-the-art optical lattice clocks, demonstrating enhanced sensitivity while preserving long coherence times and the highest accuracy.

A three-fold atom-cavity system approach will be employed: the dispersive quantum non-demolition (QND) system in the weak coupling regime, the QND system in the strong collective coupling regime, and the quantum enhancement of narrow-linewidth laser light generation towards a continuous active optical frequency standard. Cross-fertilization of such approaches will be granted by paralel theoretical investigations on the available and brand-new quantum protocols, providing cavity-assisted readout phase amplification, adaptive entanglement and squeezed state preparation protocols. Novel ideas on quantum state engineering of the clock states inside the opticaI lattice will be exploited to test possible quantum information and communication applications. By pushing the performance of optical atomic clocks toward the Heisenberg limit, Q-Clocks is expected to substantially enhance all utilizations of high precision atomic clocks, including tests of fundamental physics (test of the theory of relativity, physics beyond the standard model, variation of fundamental constants, search for dark matter) and applied physics (relativistic geophysics, chrono geodetic leveling, precision geodesy and timetagging in coherent high speed optical communication). Finally, active optical atomic clocks would have a potential to join large scale laser interferometers in gravitational waves detection.

CONSORTIUM
Coordinator: Filippo Levi, National lnstitute of Metrological Research, ltaly
Roberto Franzosi, National lnstitute of Optics, National Research Council (INO-CNR), ltaly
Jan W. Thomsen, University of Copenhagen, Denmark
Morgan Mitchell, ICFO - the lnstitute of Photonic Sciences, Spain
Jérôme Lodewyck, National Center for Scientific Research (CNRS)/ Time Space Reference Systems (SYRTE), France
Michal Zawada, Nicolaus Copernicus University in Torun, Poland

CNR Ethics Mentor:
CNR Security Advisor:

Some of the most fundamental and intriguing phenomena occurring in nature, ranging from the interaction of elementary particles to conventional and exotic matter, are described by gauge theories. The study and understanding of such phenomena in most cases is only possible by means of numerical simulations as analytical solutions are not available. These numerical simulations are one of the most complex challenge that physicists have undertaken in the last decades, attacking the problem mostly by means of Monte Carlo methods. Unfortunately, despite the enormous efforts performed and the successes achieved, many significant physical phenomena remain beyond the field of applicability of Monte Carlo methods due to a fundamental limitation, the sign problem.

As R. Feynman already pointed out when he first proposed the idea of a quantum computer, fully developed quantum technologies will be extremely effective to attack the problems currently out of reach. The goal of the QTFLAG project is to make significant two steps along this path: the first one is to develop classical simulation methods inspired by quantum information science (tensor network methods) that do not suffer from the sign problem. The second step is to develop and run quantum software on quantum simulation platforms, that is, to replace classical numerical simulations with experiments where a quantum systems in the lab mimics the physics of the lattice gauge theory of interest, allowing its study in a controlled environment.

This interdisciplinary project will exploit the knowledge from experimental and theoretical quantum optics; atomic, molecular and optical physics; quantum information science; high energy physics and condensed matter. lts results will potentially impact different fundamental and applied fields of science ranging from materials science and quantum chemistry to astrophysics. From the technological point of view, among many different potential applications, the results of this project will enable, in the long run, the study and design of novel materials with topological error correcting capabilities, which will play a centrai role in the quest for buildingfuture quantum computers.

CONSORTIUM
Coordinator: Simone Montangero, Saarland University, Germany
lgnacio Cirac, Max Planck lnstitute of Quantum Optics, Germany
Christine Muschik, lnnsbruck University, Austria
Frank Verstraete, Ghent University, Belgium
Leonardo Fallani, National lnstitute of Optics, National Research Council (INO-CNR), ltaly
Jakub Zakrzewski, Jagiellonian University, Poland

Quantum computation has been conceived to face problems which classical computer cannot selve and that can revolutionize our society, alike modelling of global economy, of the climate changes and implementation of more secure (quantum encrypted) communication schemes. Among other promising fields, quantum computer can establish a "quantum supremacy" in the solution of complex quantum physics, quantum chemistry and biology problems for drug design, which require the simulation of the interactions between many electrons. The solution of these fundamental problems promises a real revolution, whose positive benefits are even unpredictable.

As critical step towards scaling up quantum computers, researchers are trying to encode the quantum bit in a kind of quasiparticle, called Majorana fermion, which take their name from the italian phisicist Majorana, which theorized their existence at the beginning of the 20th century. This particle-like object emerges from the interactions inside materials which are characterized by exotic topological properties. David Thouless, Duncan Haldane and Michael Kosterlitz won the 2016 Nobel Prize in Physics for their theoretical study of topological phases in two-dimensional materials, A qubit working through the control of Majorana particles have the characteristic to be insensitivity to decoherence, which is the main problem that quantum computation is facing.

QUANTOX propose a novel material technological platform for the realization of topological quantum computers. lt is based on two-dimensional electron gas which are formed at the junction between two insulating oxide materials, namely the LaAI03 (LAO) and SrTi03 (STO) oxides. This platform has all the characteristics for the practical realization of theory-based proposals for topological quantum computation, and important fundamental and technological advantages. Like the possibility to scale the technology to complex systems including a large number of qubits and the possibilty to incorporate in the device layout all the element necessary for the operation of the qubit.

The project, leaded by the ltalian researchers of the CNR-SPIN institute, joined together theoretical and experimental groups among the most active and expert groups in the physics of oxide 2DEGs in the extended European Research Area (ERA), and comprises the participation of theoretical groups expert in Majorana Physics and topological quantum computation.

Our project is aimed at establishing oxide 2DEGs as a viable platform for the realization of topological quantum computers, thus launching a new technological approach to the realization of "fault tolerant" quantum computation technology.

For more information see the QUANTOX website: www.quantox.spin.cnr.it

CONSORTIUM
Coordinator: Marco Salluzzo, National Research Council - SuPerconducting and other INnovative materials and devices institute (CNR-SPIN), ltaly
Jacobo Santamaria, Complutense University of Madrid, Spain
Manuel Bibes, Joint Physics Unit CNRS/Thalès, France
Nicolas Bergeal, ESPCI Paris, France
Beena Kalisky, Bar llan University by Birad R&D Co. Ltd., lsrael
Andrea Caviglia, Delft University of Technology, Netherlands
Alexei Kalaboukhov, Department of Microtechnology and Nanoscience - MC2, Chalmers University of Technology, Sweden

The research in cavity optomechanics has recently achieved a major breakthrough: the first observation of quantum phenomena in cryogenic, optically cooled mechanical resonators (i.e., actually in macroscopic objects), as well as in the electromagnetic field interacting with such resonators. These results open the way to the exploitation of optomechanical systems as quantum sensors.

The main target of this project is indeed the creation of optomechanical sensing devices achieving the quantum limit in the measurement process, and exploiting peculiar quantum properties, of both the mechanical oscillator and the interacting radiation field, to enhance the efficiency of the measurement and to integrate the extracted information in quantum communication systems. We will develop three different platforms that, according to the present state of the art, are the most suitable to achieve our goal: (i) semiconductor nano-optomechanical disks (ii) tensioned dielectric membranes (iii) levitating nanoparticles. This parallel approach allows increasing the success probability, to extend the operating frequency range and diversify the systems for a larger versatility. Moreover, in order to study specific quantum protocols, we will exploit nano-electro-mechanical systems which have been shown to be the most suitable classical test-bench for this purpose thanks to their long coherence even at room temperature and their unprecedented control. Mechanical and optical properties of the different resonators will be improved, choosing innovative paths to advance the state of the art, in order to increase the coherent coupling rate and reduce the decoherence rate, eventually achieving quantum performance of the devices at room temperature, a crucial requirement for a realistic application scenario as sensors. Producing and manipulating quantum states of a sensor is an important pre-requisite for the quantum revolution, e.g., for implementing a quantum network that collects information from the environment and transfers it into quantum communication channels.

We will produce prototype portable sensing systems, evaluate and compare the performance of the different platforms as acceleration sensors, study the possibilities of system integration and of functionalization for future extended sensing capability.

CONSORTIUM
Coordinator: Francesco Marin, National lnstitute of Optics, National Research Council (INO-CNR), ltaly
Eva Weig, University of Konstanz, Germany
Nikolai Kiesel, University of Vienna, Austria
Ivan Favero, Laboratory of Materials and Quantum Phenomena, France
Kjetil Borkje, University College of Southeast Norway, Norway
Pasqualina Sarro, Delft University ofTechnology, Netherlands

Scientific Officer Contacts:
Francesco Marin
Department of Physics and Astronomy, University of Florence
Address: Via Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
Phone: +39 0554572033
Email: marin@fi.infn.it

When we look into a mirror, we see a perfect image of ourselves that is formed by light reflecting off the mirror surface. In contrast, when light is incident on an uneven surface such as a layer of paint or a sugar cube, it scatters in many directions, usually leading to a scrambling of any information carried on the light beam. In recent years, scientists have achieved a staggering amount of control over how light propagates through such complex media, demonstrating feats such as looking through opaque scattering walls, and sending an entire image through a tiny opticaI fiber. The QuompleX project aims to use such techniques for the delicate task of manipulating quantum information carried by particles of light.

Quantum technologies such as quantum encryption and quantum computers promise as yet unattainable levels of information security and computing power. Such technologies rely on our ability to carefully control and transport quantum states of light, tasks that are usually achieved by conventional optical elements such as beam splitters or integrated photonic circuits. However, as the quantum states in question get more complex, the devices required to control them become harder and harder to use. In QuompleX, we turn this problem around by using commonly available scattering media such as multi-mode fibers as complex linear optical networks for generating, manipulating, and transporting multi-level quantum states of light.

In this manner, QuompleX will study the theoretical limits of quantum transformations possible with complex media, and apply them for designing multi-level quantum logic gates for light. In addition, the technologies developed in QuompleX will be used for the generation of complex, multi-photon entangled states of light and for implementing noise-robust quantum communication protocols with unprecedented levels of information security.

CONSORTIUM
Coordinator: Mehul Malik, lnstitute for Quantum Optics and Quantum lnformation in Vienna, Austria
Claudio Conti, National Research Council (CNR), ltaly
Pepijn Pinkse, University of Twente, Netherlands

Topological quantum computing (TQC) is an emerging field with strong benefits for prospective applications, since it provides an elegant way around decoherence. The theory of TQC progressed very rapidly during the last decade from various qubit realizations to scalable computational protocols. However, experimental realization of these concepts lags behind. lmportant experimental milestones have been achieved recently, by demonstrating the first signatures of Majorana states which are the simplest non-Abelian anyons.

However, to realize fully topologically protected universal quantum computation, more exotic anyons, such as parafermions are required. Thus, the unambiguous demonstration of parafermion states will have a great impact on the development of universal quantum computation. The experimental realization of parafermions is challenging, since they are based on the combination of various ingredients, such as crossed Andreev reflection, electron-electron or spin-orbit interaction, and high quality quantum conductors. Thus, the investigation of all these ingredients is essential and timely to achieve further experimental progress. The team of SuperTop is composed of six leading groups with strong and complementary experimental background in these areas with the aim to realize parafermions in double nanowire-based hybrid devices (DNW) forthe first time.

The main objectives of SuperTop are: a) development of different DNW geometries, which consist of two parallel 1D spin-orbit nanowires coupled by a thin superconductor stripe and b) investigation of the emerging exotic bound states at the superconductor/semiconductor interface of the DNW.

SuperTop first grows state-of-the-art lnAs and lnSb based nanostructures, in particular lnAs nanowires (NWs) with in-situ grown epitaxial superconducting layer, NWs with built-in lnP barriers and lnSb nanoflakes. Based on these high quality materials, different device geometries of DNW are fabricated and the emerging novel states are investigated. The topological character, quantum phase transition, coherence time, coupling strength to QED as key features of the engineered new states are planned to be addressed by various cutting-edge low temperature measurement techniques (e.g. non-local spectroscopy, noise, current-phase relationship measurement or integration into coplanar resonators).

The experimental team of SuperTop is supported by in-house theoretical experts of TQC, who will contribute to the interpretation of the results and development of technologically feasible topologically protected quantum architectures.

CONSORTIUM
Coordinator: Szabolcs Csonka, Budapest University of Technology and Economics, Hungary
Jesper Nygard, University of Copenhagen, Denmark
Takis Kontos, National Center for Scientific Research (CNRS), France
Lucia Sorba, lnstitute of Nanoscience, National Research Council (CNR), ltaly
Attila Geresdi, Delft University of Technology, Netherlands
Christian Schonenberger, University of Basel, Switzerland

Scientific Officer Contacts:
Lucia Sorba
Institute of Nanoscience, National Research Council (NANO-CNR)
Phone: +39 050509118
Email: lucia.sorba@nano.cnr.it

The long-term vision of TAIOL project is to develop a novel class of quantum sensors based on trapped atom interferometry with performances that will overcome state of the art, and to extend their range of operation for high precision measurements in applied and fundamental physics.

In such sensors, atoms are split into a quantum superposition of two spatially separated states in the presence of an external force. The resulting difference in potential energy between the two spatial states leads to a differential phase evolution, which is read out by recombining them after some interrogation time, thus creating an atomic interferometer. In this measurement scheme, the sensitivity in the force measurement increases linearly with the spatial separation and the interrogation time. The use of trapped atoms allows here for reaching very long interrogation times, of up to several seconds, without having to increase the size of the physical package. This is a key advantage with respect to sensors based on freely falling atoms, for which such long interrogation times would imply free fall distances of tens of meters, which allows to envision the development of very compact sensors. In addition, it enables to perform local measurements of external fields with very high spatial resolution, of less than a micrometer.

The aim of TAIOL is to push the performance of sensors based on atom interferometry, using ultracold atoms confined in optical lattices, well beyond the levels reached by the few proof-of-principle experiments that have explored so far guided and trapped architectures. For that purpose, innovative approaches and methods will be explored for separating split atomic samples further apart, from tens of micrometers to millimeters, while maintaining the quantum coherence, and for taming harmful effects related to the interactions between the trapped atoms, by either controlling the strength of these interactions or using novel sources of ultra-cold atoms. The project outputs will open new possibilities for a wide range of applications, such as inertial sensing, inertial navigation, gravity field mapping, physical laws testing, surface interactions, with the perspective of future industrial implementations.

CONSORTIUM
Coordinator: Franck Pereira dos Santos, Paris Observatory/ Time Space Reference Systems (SYRTE), France
Andrea Bertoldi, LP2N, France
Ernst Rasel, lnstitute of Quantum Optics, Leibniz University of Hannover, Germany
Marco Fattori, National lnstitute of Optics, National Research Council (INO-CNR), ltaly
Jan Chweder\czuk, Faculty of Physics, University of Warsaw, Poland