203 research outputs found
Integrated Generation of High-dimensional Entangled Photon States and Their Coherent Control
We demonstrate the generation of high-dimensional entangled photon pairs with a Hilbert-space dimensionality larger than 100 from an on-chip nonlinear microcavity, and introduce a coherent control scheme using standard telecommunications components
Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations
Introduction Chloride shift is the movement of chloride between red
blood cells (RBC) and plasma (and vice versa) caused by variations in
pCO2. The aim of our study was to investigate changes in plasmatic
strong ion diff erence (SID) during acute variations in pCO2 and their
possible role in the compensation for hypocapnic alkalosis.Methods Patients admitted in this year to our ICU requiring extracorporeal
CO2 removal were enrolled. Couples of measurements
of gases and electrolytes on blood entering (v) and leaving (a) the
respiratory membrane were analyzed. SID was calculated as [Na+]
+ [K+] + 2[Ca2+] \u2013 [Cl\u2013] \u2013 [Lac\u2013]. Percentage variations in SID (SID%)
were calculated as (SIDv \u2013 SIDa) x 100 / SIDv. The same calculation was
performed for pCO2 (pCO2%). Comparison between v and a values was
performed by paired t test or the signed-rank test, as appropriate.
Results Analysis was conducted on 205 sample-couples of six enrolled
patients. A signifi cant diff erence (P <0.001) between mean values of
v\u2013a samples was observed for pH (7.41 \ub1 0.05 vs. 7.51 \ub1 0.06), pCO2
(48 \ub1 6 vs. 35 \ub1 7 mmHg), [Na+] (136.3 \ub1 4.0 vs. 135.2 \ub1 4.0 mEq/l), [Cl\u2013]
(101.5 \ub1 5.3 vs. 102.8 \ub1 5.2 mEq/l) and therefore SID (39.5 \ub1 4.0 vs.
36.9 \ub1 4.1 mEq/l). pCO2% and SID% signifi cantly correlated (r2 = 0.28,
P <0.001). Graphical representation by quartiles of pCO2% is shown in
Figure 1.
Conclusions As a reduction in SID decreases pH, the observed
movement of anions and cations probably limited the alkalinization
caused by hypocapnia. In this model, the only source of electrolytes
are blood cells (that is, no interstitium and no infl uence of the kidney
is present); it is therefore conceivable to consider the observed
phenomenon as the contribution of RBC for the compensation of acute
hypocapnic alkalosi
Optically induced metal-to-dielectric transition in Epsilon-Near-Zero metamaterials
This work was supported by the EPSRC grant EP/ J004200/1. D.F. acknowledges financial support from the European Research Council under the European Union Seventh Framework Programme (FP/2007-2013)/ERC GA 306559 and EPSRC (UK, Grant No. EP/J00443X/1). L.C. and M.C. acknowledge the support from the People Programme (Marie Curie Actions) of the European Union’s FP7 Programme THREEPLE (GA 627478) and KOHERENT (GA 299522). A.C. and C.R. acknowledge support from U.S. Army International Technology Center Atlantic for financial support (Grant No. W911NF-14-1-0315).Epsilon-Near-Zero materials exhibit a transition in the real part of the dielectric permittivity from positive to negative value as a function of wavelength. Here we study metal-dielectric layered metamaterials in the homogenised regime (each layer has strongly subwavelength thickness) with zero real part of the permittivity in the near-infrared region. By optically pumping the metamaterial we experimentally show that close to the Epsilon-Near-Zero (ENZ) wavelength the permittivity exhibits a marked transition from metallic (negative permittivity) to dielectric (positive permittivity) as a function of the optical power. Remarkably, this transition is linear as a function of pump power and occurs on time scales of the order of the 100 fs pump pulse that need not be tuned to a specific wavelength. The linearity of the permittivity increase allows us to express the response of the metamaterial in terms of a standard third order optical nonlinearity: this shows a clear inversion of the roles of the real and imaginary parts in crossing the ENZ wavelength, further supporting an optically induced change in the physical behaviour of the metamaterial.Publisher PDFPeer reviewe
Controlling hybrid nonlinearities in transparent conducting oxides via two-colour excitation
Nanophotonics and metamaterials have revolutionised the way we think about
optical space (epsilon, mu), enabling us to engineer the refractive index
almost at will, to confine light to the smallest of the volumes, and to
manipulate optical signals with extremely small footprints and energy
requirements. Significant efforts are now devoted to finding suitable materials
and strategies for the dynamic control of the optical properties. Transparent
conductive oxides exhibit large ultrafast nonlinearities under both interband
and intraband excitations. Here, we show that combining these two effects in
aluminium-doped zinc oxide via a two colour laser field discloses new material
functionalities. Owing to the independence of the two nonlinearities the
ultrafast temporal dynamics of the material permittivity can be designed by
acting on the amplitude and delay of the two fields. We demonstrate the
potential applications of this novel degree of freedom by dynamically
addressing the modulation bandwidth and optical spectral tuning of a probe
optical pulse
Enhanced nonlinear refractive index in ε-near-zero materials
New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here, we demonstrate a universal approach based on the low linear permittivity values attained in the ε-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a sixfold increase of the Kerr nonlinear refractive index (n2) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to ultrafast light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics.Publisher PDFPeer reviewe
Scaling On-Chip Entangled Photon States to Higher Dimensions
Considerable efforts have recently focused on advancing quantum information pro- cessing by increasing the number of qubits
(the simplest unit of quantum information) in nonclassical systems such as ultracold atoms and superconducting circuits. A complementary approach to scale up infor- mation content is to move from two-level (qubit) to multilevel (quDit) systems
Integrated plasmonic circuitry on a vertical-cavity surface-emitting semiconductor laser platform
Integrated plasmonic sources and detectors are imperative in the practical development of plasmonic circuitry for bio- and chemical sensing, nanoscale optical information processing, as well as transducers for high-density optical data storage. Here we show that vertical-cavity surface-emitting lasers (VCSELs) can be employed as an on-chip, electrically pumped source or detector of plasmonic signals, when operated in forward or reverse bias, respectively. To this end, we experimentally demonstrate surface plasmon polariton excitation, waveguiding, frequency conversion and detection on a VCSEL-based plasmonic platform. The coupling efficiency of the VCSEL emission to waveguided surface plasmon polariton modes has been optimized using asymmetric plasmonic nanostructures. The plasmonic VCSEL platform validated here is a viable solution for practical realizations of plasmonic functionalities for various applications, such as those requiring sub-wavelength field confinement, refractive index sensitivity or optical near-field transduction with electrically driven sources, thus enabling the realization of on-chip optical communication and lab-on-a-chip devices
The bolometers as nuclear recoil detectors
Our group is involved in experiments using bolometric detectors since ten years for rare event searches like double beta decay or Dark Matter interactions. During last year, to check the quenching factor of TeO 2 bolometers, we have measured the nuclear recoils at energy as low as 15 keV in our experimental apparatus at Laboratori Nazionali del Gran Sasso. Two 72g TeO 2 detectors were exposed under vacuum to a 228Ra a source that implanted on them 224Ra nuclei. The nuclei emitted by the implanted source were detected in one bolometer in coincidence with the corresponding a particles in the other. The energy spectrum of the 103.4 keV 224Ra nuclei has been obtained with an energy resolution of about 12 keV. Furthermore an a measurement of Roman lead has exploited also the sensitivity of this technique to check for ultralow activity in matter, taking advantage of the source,detector approach. A limit on the 210Pb contamination in roman lead as low as 4 mBq/Kg has been obtained. ( 1998 Elsevier Science B.V. All rights reserved
Preliminary results on the performance of a TeO2 thermal detector in a search for direct interactions of WIMPS
Abstract During a Double Beta Decay experiment performed at Laboratori Nazionali del Gran Sasso, a 1548 hours background spectrum was collected with a 340 g TeO2 thermal detector. An analysis of this spectrum has been carried out to search for possible WIMP signals. The values for parameters which are essential in the search for WIMPs, like energy resolution (2 keV), energy threshold (13 keV) and nuclear recoil quenching factor (≥ 0.93) have been experimentally determined and are discussed in detail. The spectrum of recoils induced by α decays has been directly observed for the first time in coincidence with the α particle pulse. Preliminary limits on the spin-independent cross sections of WIMPs on Te and O nuclei have been obtained
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