ICFO – The Institute of Photonic Sciences

About: ICFO – The Institute of Photonic Sciences is a facility organization based out in Barcelona, Spain. It is known for research contribution in the topics: Quantum & Quantum entanglement. The organization has 872 authors who have published 1965 publications receiving 56273 citations.

Dynamic molecular monitoring of retina inflammation by in vivo Raman spectroscopy coupled with multivariate analysis.

Abstract: Retinal tissue is damaged during inflammation in Multiple Sclerosis. We assessed molecular changes in inflamed murine retinal cultures by Raman spectroscopy. Partial Least Squares-Discriminant analysis (PLS-DA) was able to classify retina cultures as inflamed with high accuracy. Using Multivariate Curve Resolution (MCR) analysis, we deconvolved 6 molecular components suffering dynamic changes along inflammatory process. Those include the increase of immune mediators (Lipoxygenase, iNOS and TNFα), changes in molecules involved in energy production (Cytochrome C, phenylalanine and NADH/NAD+) and decrease of Phosphatidylcholine. Raman spectroscopy combined with multivariate analysis allows monitoring the evolution of retina inflammation. Raman spectroscopy analysis of the Retinal Ganglion Cell layer of the retina. (A) Design of the analysis of the Ganglion cell layer (GCL) and Retinal Nerve Fiber Layer (RNFL) of the retina based in the physical properties of laser light and anatomical structure of retinal layers. (B) Examples of raw Raman spectra from representative retina sample after 10 hours incubation time (black) and LPS treated retina sample after 10 hours incubation time (red) and 12 hours incubation time (blue). (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Photothermal Engineering of Graphene Plasmons.

Abstract: Nanoscale photothermal sources find important applications in theranostics, imaging, and catalysis. In this context, graphene offers a unique suite of optical, electrical, and thermal properties, which we exploit to show self-consistent active photothermal modulation of its nanoscale response. In particular, we predict the existence of plasmons confined to the optical landscape tailored by continuous-wave external-light pumping of homogeneous graphene. This result relies on the high electron temperatures achievable in optically pumped clean graphene while its lattice remains near ambient temperature. Our study opens a new avenue toward the active optical control of the nanophotonic response in graphene with potential application in photothermal devices.

Relevant aspects of unmixing/resolution analysis for the interpretation of biological vibrational hyperspectral images

Abstract: The use of multivariate unmixing/resolution methods for the analysis of biological vibrational hyperspectral images is crucial to characterize the morphology and spectral signatures of the different biological tissues or cell compartments. This work provides a general data analysis protocol to interpret Raman and FT-IR hyperspectral images of biological samples. To do so, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) is the core tool proposed. The protocol starts by describing dedicated preprocessing steps suitable to handle the nature and artifacts of the spectroscopic technique used. Later on, the focus is on the use of MCR-ALS to analyze single images or image multiset structures that contain images with related information. Relevant issues related to advanced use of MCR-ALS on biological image analysis, such as the modeling of mixed non-biological signal contributions or the elucidation and active use of information related to the presence/absence of biological contributions in different images (samples) in multiset structures, are described. Additional aspects, such as the only use of the FT-IR fingerprint region vs. using extended spectral ranges in FT-IR to improve the differentiation among contributions, are also considered. The proposed data analysis methodology is demonstrated on real Raman and FT-IR images from zebrafish tissue cryosections.

Dynamic control of Purcell enhanced emission of erbium ions in nanoparticles.

Abstract: The interaction of single quantum emitters with an optical cavity enables the realization of efficient spin-photon interfaces, an essential resource for quantum networks. The dynamical control of the spontaneous emission rate of quantum emitters in cavities has important implications in quantum technologies, e.g., for shaping the emitted photons’ waveform or for driving coherently the optical transition while preventing photon emission. Here we demonstrate the dynamical control of the Purcell enhanced emission of a small ensemble of erbium ions doped into a nanoparticle. By embedding the nanoparticles into a fully tunable high finesse fiber based optical microcavity, we demonstrate a median Purcell factor of 15 for the ensemble of ions. We also show that we can dynamically control the Purcell enhanced emission by tuning the cavity on and out of resonance, by controlling its length with sub-nanometer precision on a time scale more than two orders of magnitude faster than the natural lifetime of the erbium ions. This capability opens prospects for the realization of efficient nanoscale quantum interfaces between solid-state spins and single telecom photons with controllable waveform, for non-destructive detection of photonic qubits, and for the realization of quantum gates between rare-earth ion qubits coupled to an optical cavity. Control of quantum emitters is needed in order to enable many applications. Here, the authors demonstrate enhancement and dynamical control of the Purcell emission from erbium ions doped in a nanoparticle within a fiber-based microcavity.

Separability of diagonal symmetric states: a quadratic conic optimization problem

Abstract: We study the separability problem in mixtures of Dicke states i.e., the separability of the so-called Diagonal Symmetric (DS) states. First, we show that separability in the case of DS in $C^d\otimes C^d$ (symmetric qudits) can be reformulated as a quadratic conic optimization problem. This connection allows us to exchange concepts and ideas between quantum information and this field of mathematics. For instance, copositive matrices can be understood as indecomposable entanglement witnesses for DS states. As a consequence, we show that positivity of the partial transposition (PPT) is sufficient and necessary for separability of DS states for $d \leq 4$. Furthermore, for $d \geq 5$, we provide analytic examples of PPT-entangled states. Second, we develop new sufficient separability conditions beyond the PPT criterion for bipartite DS states. Finally, we focus on $N$-partite DS qubits, where PPT is known to be necessary and sufficient for separability. In this case, we present a family of almost DS states that are PPT with respect to each partition but nevertheless entangled.