Published paper in Journal of Lightwave Technology on September 2019

Phase shifters are devices that offer the possibility to dynamically reconfigure the properties of photonic integrated circuits (PICs), thus greatly extending their quality and applicability. In this paper, we provide a thorough discussion of the main problems that one can encounter when using thermal phase shifters. We show how all these issues can be solved and the performance improved by manufacturing optimized thermal shifters in femtosecond-laser-written PICs (FLW-PICs). The unprecedented results in terms of power dissipation, miniaturization and stability enable the scalable implementation of reconfigurable FLW-PICs for exploitation in many applications.

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Published paper in Physical Review Letters on August 2019

With this work, we report on the quantum storage of a heralded frequency-multiplexed single photon in an integrated laser-written rare-earth doped waveguide.  In particular, a frequency-multimode photon is stored in a praseodymium-doped waveguide using the atomic frequency comb (AFC) scheme and we demonstrate that the storage preserves the nonclassical properties of the single photon.

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Published paper in Advanced Photonics on May 2019

Boson sampling is a computational problem that has recently been proposed as a candidate to obtain an unequivocal quantum computational advantage. This prospect has stimulated much effort resulting in the experimental implementation of progressively larger devices. We review recent advances in photonic boson sampling, describing both the technological improvements achieved and the future challenges.

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Published paper in Physical Review Letters on April 2019

Decay of an excited system to its ground state is a ubiquitous phenomenon in all branches of physics. Here we use a photonic simulator to show specific and counterintuitive features of such decay in quantum systems. Significant deviations from the widely accepted exponential decay dynamics are experimentally demonstrated, in particular showing oscillatory behavior at very long decay times. Such oscillation are due to quantum interference effects and mean that in this region the decay process is not monotonic but there is the possibility that the system is re-excited by the interaction with the environment.

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Published paper in Optica on March 2019

Efforts to develop quantum computers are motivated by the promise of a tremendous speedup in several computational tasks such as quantum simulation or factoring. A milestone in this quest will be to provide evidence of quantum supremacy, which occurs when a quantum device solves a family of problems faster than state-of-the-art classical computers. The technological race toward this achievement goes hand in hand with the development of classical protocols that can discern genuine quantum processes. Here, we provide a step forward in this direction by presenting a machine-learning algorithm to detect malfunctions within a class of quantum hardware used to demonstrate quantum supremacy, relying only on experimental data.

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Published paper in Nature Photonics on February 2019

3D nano-optical devices created directly inside dielectric crystals like YAG and sapphire by exploiting femtosecond laser pulses. This discovery is very important, because to date, through the conventional techniques of micro- and nano-processing, it is only possible to modify these crystals on their surface, thus obtaining purely 2D structures. These results pave the way for the development of new-generation photonic devices.

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Published paper in Physical Review X on January 2019

Experimental implementation of a reconfigurable integrated multimode interferometer designed for simultaneous estimation of two optical phases. We verify the high-fidelity operation of the implemented device and demonstrate quantum-enhanced performances in two-phase estimation with respect to the best classical case, post-selected to the number of detected coincidences. This device can be employed to test general adaptive multiphase protocols due to its high reconfigurability level, and represents a powerful platform to investigate the multiparameter estimation scenario.

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