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Research activity and work-packages

**WP1 – Fundamental quantum science**

**WP2 – Quantum communication**

**WP3 – Quantum computing**

**WP4 – Quantum simulations**

**WP5 – Future sensors and metrology**

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__WP1: Fundamental quantum science__

__WP1: Fundamental quantum science__

Within WP1 we will study the fundamental implications of Quantum Mechanics to uncover the large potential of the theory, and give theoretical background and guidance to experiments and applications. Our investigations along these lines will touch different directions:

- We will formulate quantitative predictions on lattice gauge models in various contexts, from both the points of view of fundamental science and experimental implementation, including: 1 + 1 or 2 + 1 systems in or out of balance, at zero or finite temperature, with Abelian or non-Abelian gauge symmetries, and even in open quantum systems in transient or stationary dynamics.
- We will investigate possible protocols and methodologies of analogue implementation of lattice gauge models in quantum simulators available with today’s technologies, such as ion traps, dipole-dipole systems, or ultracold atoms in magnetic and optical potentials.
- We will investigate the quantum many-body physics of quantum gases of ultracold atoms as well as quantum fluids of photons and polaritons with the aim of unveiling new quantum phases of matter with novel properties.
- We will investigate general issues of topological physics from the quantum Hall effect to topological insulators, both in the traditional quantum condensed-matter context as well as in their novel transposition to topological photonics and strongly correlated states of light. Key concepts will be synthetic gauge fields, spin-orbit coupling, integer and fractional quantum Hall effects, anyonic statistics and topological degeneracies.
- We will investigate the physics of crystal defects in quantum materials (e.g. diamond, SiC) like energy level structure, spin properties, electric and magnetic dipole moments orientation, etc., in view of their use as virtual atoms.
- We will investigate basic quantum optical processes in the microwave domain using low-temperature superconductor-based devices (the so-called circuit-QED systems). INO is interested in the theoretical quantum optical aspects of these systems, while FBK-CMM is experimentally investigating fundamental interactions between electromagnetic radiation and matter through Circuit Quantum Electrodynamics (C-QED) studies. In particular, the research involves single photon interactions with artificial atoms (objects with discrete energy levels). In this case, this is done by coupling superconductive resonators with waveguides and superconductive q-bits. This last is realised with Josephson junction and it is the essential building block for every C-QED device. The clean room at FBK is developing a technique for realising Josephson junction enabling this research within Q@TN.
- We will investigate the possibility of using Circuit-QED based devices as a co-processing tool to study Hamiltonians of fundamental interest in nuclear physics. In particular we will try to find solutions to address the exponential growth of complexity of the problem due to the explicit dependence of all the interactions on the spin/isospin degrees of freedom of baryons.
- All the above points will be supported by fundamental studies in mathematics applied to quantum mechanics and quantum information science. Among them, algebraic formulations, real and quaternionic functional analysis, spectral and stochastic analysis will be used to focus on fundamental quantum structures and problems like measurement and decoherence. Quantum control, quantum information and related areas as quantum entanglement will be investigated, making also use of tensor decomposition and tensor network theory. Functional integration will be applied to Feynman path integral techniques.

**Areas of action, and the involvement of the partners:**

- Quantum measurements (DM, DF)
- Quantum information (DM, INO)
- Fundamental quantum physics (DM, DF, ECT*, INO)
- Quantum many-body physics (DF, INO, ECT*)
- Quantum optics (DF, INO, CMM, ECT*)
- Topological physics and photonics (DF, DM, INO, ECT*)
- Quantum materials (DF, IFN, CMM, DICAM)
- Mechanical analogues of quantum systems (DF, DICAM, INO)

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__WP2: Quantum communications__

__WP2: Quantum communications__

Quantum technologies will have an enormous impact on communications, as they can empower intrinsic secure exchange of information (with distribution of quantum keys) and carry a large amount of data in q-bit transfer, with respect to current binary units. The research requires expertise in theoretical aspects of quantum key distributions, q-bit generation and exchange, communication and wireless technology, cryptography, experimental and hardware design capability in photonics, sensors, microelectronics integration and network architecture and management.

Several topics relevant to quantum communication are part of the research roadmaps and of the scientific/technology platforms of the proposing Institutes. CMM and DF have performed R&D on Quantum Random Number Generators (two shared patents as a result of the SIQURO project), and, in collaboration with DM, we are planning to submit a funding proposal (within a network of 6 international institutes) to the QT Flagship in the beginning of 2018 for further development and improved integration of the QRNG chip. The project foresees the development of an integrated CMOS compatible quantum number generator with both emitter and receiver on the very same chip. The generator will allow simple upscaling to increase the bit-rate and allow for post processing and direct use of the random numbers in a more complex CMOS chip fabricated in the very same process, or something similar. Within this scheme we aim also to integrate a test of Bell inequalities on the chip to on-the-fly prove the quantum nature of the generation mechanism. This will also be used as a cheap, low power, compact, light source for QKD. Unambiguous detection of entangled photons will be of central importance to quantum communication. In the context of using quantum technologies in communication network, CREATE-NET has started an internal research activity in view of creating a possible lab infrastructure for testing.

DM has expertise in the definition of novel quantum key distribution protocols for secure communications based on several quantum features like entanglement, quantum dynamics, quantum measurements. Physical implementation of quantum cryptographic schemes will be considered in terms of optical elements in collaboration with DF.

Activities in the framework of the physical-layer secure communications are carried out at DISI in which the main focus is on the design of the transmitting antenna systems and their control through suitable beam-forming strategies. Future research plans will consider the design of quantum nano-antennas and quantum nano-antenna array models, the analysis of the radiation patterns and of the pattern features for enabling advanced secure communication applications and secure wireless networking.

INO is playing a leading role in the theoretical study of topological effects in photonics and their potential applications to novel photonic devices. This research was recently supported by the EU-Marie-Sklodowska-Curie “SynOptic” project. The presence of topologically protected propagation channels holds strong promises towards the realization of light sources and quantum communication devices whose operation is robust against disorder and decoherence. DF and FBK are submitting a FET project in early 2018 to exploit topological photonics into devices (project ARTYSTE). Furthermore, strongly correlated states of light such as fractional Hall liquids have a potential use as a source of quantum light to be fed into photonic networks and/or for one-way quantum computing applications.

IFN will apply femtosecond laser nanofabrication to precisely fabricate 3D photonic circuits and nitrogen-vacancy (NV) centers in single-crystal synthetic diamond. Integrated optical circuits and NVs could open the door to more sophisticated quantum photonic networks in diamond, exploiting optically linked single NVs for single photon sources or solid-state qubits. Single photon emission will be investigated also using specific glass ceramic waveguides activated by rare earth ions and/or implanting rare earth ions in silicon.

In DII, SiC and SiOC nanostructures are used to realize single photon emitters; point defects are formed in quantum dots by ionizing radiation to realize single photon sources and low noise single photon detectors are designed and tested. All these devices can be suitably integrated in prototypes for quantum communication.

**Areas of action, and the involvement of the partners:**

- Single photon sources and detectors for quantum communication (DII, DF, CMM, IFN);
- Integrated custom photonics chips (DF, CMM, IFN);
- Quantum Random Number Generators (DF, CMM, DISI, DM);
- Secure communications (DISI, DM, ICT, CREATE-NET) ;
- Quantum Key Distribution (DM, DF, CREATE-NET) ;
- Topological photonics (DF, INO, ECT*).

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__WP3: Quantum computing__

__WP3: Quantum computing__

Quantum computing is the awaiting next revolution in information technology as it will empower computing capabilities several orders of magnitude better than currently envisaged. The research activity on Annealing and Machine Learning within DISI and ICT will deal with the general problem of implementation of decision and optimization algorithms on quantum annealing architectures, including –but not restricted to– optimization for machine learning applications. Initially we plan to explore the implementation of known Quantum Genetic Optimization Algorithms (QGOA) on existing architectures, for example D-Wave’s. One goal is the development of data-driven multi-step original optimization schemes for quantum annealers. Design and verification of quantum algorithm is also an important aspect, which will be studied at ICT. We also plan to explore strategies for quantum deep learning, including e.g. quantum computing approaches to train Boltzmann machines and other deep architectures applied to different application domains such as computer vision and bioinformatics. Here a collaboration between DISI and DF started to use matrix of ring resonators for quantum neural network. Another important goal is the development of efficient encoding of Boolean satisfiability (SAT) and related problems of Software Optimization into quantum annealing architectures for the solution of hard combinatorial problems. Weighted Model Counting and Bayesian Inference for Statistical Relational Learning approaches to probabilistic inference are a natural candidate for adaptation to quantum annealers. A final goal is the formulation of cryptography schemes for secure communications that include a quantum annealer that can be available to the communicating parties, or to the eavesdropper, or both.

In collaboration with computer science partners, INO will investigate possible applications of strongly correlated states of light as input states for quantum computing, in particular in its “one-way” flavour.

Many different physical systems are currently investigated to implement a quantum computer ranging from nuclear magnetic resonance of molecular systems, Josephson junctions of superconducting circuits, quantum dot computers, linear optical quantum computers or diamond vacancy base quantum computers to mention only a few ones. CMM and DF within the project Siquro started to develop integrated optical circuits which perform the basic linear quantum operations for computers and simulators. A strong theoretical backbone is here needed in order to implement novel software and circuit design to achieve the desired quantum operations; DM, DF, DISI, and ICT are involved in this area. Finally, CMM, ICT and DF have submitted a FET proposal to demonstrate a hybrid classical and quantum computer architecture which is transparent to the actual hardware used.

**Areas of action, and the involvement of the partners:**

- Single photon sources for quantum computing (DII, DF, CMM, IFN);
- Software production, test and verification (ICT);
- Cognitive computing, Big Data, Deep Learning (ICT, ECT*, DISI);
- Annealing e machine learning (DISI, DF, DM, ICT);
- Software optimisation (DISI, ICT);
- Computer architecture (ICT, CMM, DF, DISI);
- Secure communications (DISI, DM, ICT).

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__WP4: Quantum simulations__

__WP4: Quantum simulations__

Quantum simulations (QS) allow studying many problems that are extremely difficult (or impossible even to the current super-computers) computational challenges. Controllable quantum systems can be used to approach these untreatable problems in many fields. WP4 will research into the design and construction of systems for quantum simulations, from theory to applications to well defined problems.

The Q@TN partners are already active on this topic. FBK has been pursuing miniaturisation of photonic circuits with SOI and Si2Ni2O for compact chips with potential for integrating entangled or single (quantum dots) photon sources and sensors. DF and INO are involved in two FET-Proactive projects in quantum technologies, QUIC and AQuS. The latter was specifically devoted to analogue quantum simulators using ultra-cold atoms and polariton gases. CMM and ICT (proposal coordinators) and DF, together with 7 other international partners have submitted a FET-Open project proposal (INQUEST) to investigate portable, easy-to-use, performant Quantum Simulators based on silicon photonics and electronics with the objective to set cornerstone technology for simulating quantum mechanical problems with a compact device. Around this chip, the consortium plans for a hybrid integrated system hosting the “software level” where quantum algorithms will interpret the simulation results from the hardware. In general, quantum simulations can be built using various technology platforms that are part of the knowledge base and fabrication capability of Q@TN, and in particular: ultra-cold atomic gases, NVs, integrated photonics, atom chips.

INO, DF and DM have an ongoing experimental activity on quantum simulations, also involving the support of INFN-TIFPA. Ultracold atomic gases in the Bose-condensed phase are studied to address analogues of open problems in particle physics and fundamental interactions such as the quark confinement. INO is also playing a leading role in the theoretical study of quantum simulators of gravitational and curved-space-time quantum field phenomena such as dynamical Casimir and Hawking emission and super-radiance effects from black holes and the consequent back-reaction and evaporation phenomena. Theoretical studies can be complemented with experiments using spinorial ultracold atoms at DF and INO, and using the circuit-QED platform that is planned to be developed at CMM.

The joint use of quantum simulations and innovative system-by-design engineering paradigms (currently developed at DISI for designing new engineered materials, meta-materials, and electromagnetic technologies), exploiting quantum-level unit cells as building blocks, will allow to include more degrees of freedom in the design process for obtaining unforeseen and unconventional manipulation and tailoring of the electromagnetic wave interactions.

The use of electronic signal processing at DII will enable the implementation of extended sensor arrays supported by remote control and analyses of signals. Distributed sensor platforms can be used to model or simulate quantum systems. In addition, the material production facilities of DII offer a powerful platform to realize new quantum materials based on the design performed by the quantum simulations within Q@TN.

**Areas of action, and the involvement of the partners:**

- QS for nuclear and sub-nuclear physics (DF, ECT*);
- QS for solid state and condensed matter (DF, INO);
- QS for astrophysics, cosmology, particle physics, gravity (DF, DM, INO);
- QS and quantum material engineering (DISI, DICAM, DII).

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__WP5: Future sensors and metrology__

__WP5: Future sensors and metrology__

Sensors based on quantum effects can attain sensitivity levels now unimaginable. Moreover, sensors are key parts in all applications of QST. For example, low dark rate high quantum efficiency single photon sensors are key components of every system involving the use of light. CMM is frontrunner in this technology and aims at maintaining a leadership role setting record performance. FBK is the coordinator of the Supertwin project funded by the EU-FET program, to develop novel microscopy using entangled photons. CMM is also investigating fundamental interactions between electromagnetic radiation and matter through Circuit Quantum Electrodynamics (C-QED) studies. In particular, the research involves single photon interactions with artificial atoms (objects with discrete energy levels). In this case, this is done by coupling superconductive resonators with waveguides and superconductive q-bits. This last is realised with Josephson junctions and it is the essential building block for every C-QED device. The clean room of FBK is developing a technique for realising Josephson junctions enabling this research within Q@TN, and has also the technical expertise for producing the atom chips required for a number of experiments within this project.

The experimental laboratory of INO, in an ongoing collaborative effort with the Italian Institute of Metrological Research (INRIM), is currently involved in the realization of novel optical atomic clock which is expected to outperform the current state of the art in the field by applying advanced quantum protocols based on spin-squeezing and quantum non-demolition measurements. On a related topic, INO and CMM will develop novel technologies devoted to the realization of guides for cold atoms through silicon structures, with the goal of miniaturizing the current (bulky) opto-electronic devices typically employed in optical clocks for the atomic sample preparation and read-out.

As mentioned in WP1 and WP2, single photon sensors will be also based on waveguides with rare earth ion crystal embedded in nanocrystals and NV centers in diamond. Microresonators coupled to emitting center will be investigated for the same objective. IFN has the necessary fabrication facilities and the necessary collaborations, to succeed in. Based on the laser fabrication technology developed in WP2 for diamond, spin-based sensors based on waveguide-coupled NV centers will be applied to applications such as magnetometry, electrometry or thermometry. The further integration of these waveguides with microfluidic channels, which could be made through the etching of graphitic tracks written with femtosecond laser pulses, open up the possibility of lab on chip applications.

DF uses NV centers in diamond as nanomagnetometers for the detection of weak electromagnetic fields, even in biological contexts. DF demonstrated a new original process based on graphite-laser ablation in a controlled N-atmosphere to produce fluorescent nano-diamonds containing controlled number of NV centers. Tests for biological materials analysis are now underway in cooperation with IIT in Rovereto. The magnetic fields generated by the activity of neurons in the brain could be detected with the use of nanodiamond-based quantum sensors. This could eventually allow scientists to deepen their understanding of neurodegenerative diseases such as Alzheimer’s disease.

DF, in collaboration with IFN, is interested to develop high-Q 1D photonic crystals coupled with a micro-cantilever to develop high sensitive opto-mechanical system for the detection of gravitational wave.

DF studies quantum biological mechanism to model receptor mechanisms in living systems. Examples are inelastic electron tunnelling spectroscopy potentially involved in olfaction or entangled radical pair formation likely to underlie magnetic sensing. The characterization of these fundamental sensory mechanisms is a first step towards bio-inspired micro-sensors in artificial noses or magnetic vision.

At DII, there is a quite long tradition in the development and testing of materials and detectors for chemical and physical sensors. DII develops integrated quantum detectors for signal processing or for multivariate detection methods.

**Areas of action, and the involvement of the partners:**

- Quantum nose (DF, CIMEC);
- Micro-magnetic sensors (DF, IIT, DICAM, CMM, IFN);
- Gravitational wave sensors, opto-mechanical systems (DF, DICAM, IFN);
- Single photon sensors and integrated sensor systems (DII, DF, DICAM, CMM, IFN);
- Quantum Metrology
- Atomic clocks (INO, CMM);
- Non-destructive measurements in opto-mechanics (DF, DICAM, CMM).