Search

We present the experimental realization of a scheme, based on single-photon interference, for implementing superpositions of distinct quantum operations. Its application to a thermal light field (a well-categorized classical entity) illustrates quantum superposition from a new standpoint and provides a direct and quantitative verification of the bosonic commutation relation between creation and annihilation operators. By shifting the focus towards operator superpositions, this result opens interesting alternative perspectives for manipulating quantum states., 4 pages, 3 figures, to appear in Physical Review Letters

We investigate, for the first time, the impact of deep trench isolation on the total ionizing dose (TID) and single event upset (SEU) tolerance of advanced SiGe HBTs. We employ a combination of 63MeV protons, 10keV X-rays, and 36MeV oxygen ion microbeam irradiation and compare a 3rd generation, high-performance (HP), deep-trench isolated, SiGe BiCMOS platform with its cost-performance (CP) variant without deeptrenches. Although the CP SiGe HBTs are shown to be more susceptible to TID damage, the elevated damage is not attributed to variations in deep trench isolation (DTI), but to spacer oxide differences. CP SiGe HBTs are surprisingly found to offer a potential built-in self-mitigation mechanism for SEU, which is a direct result of the influence of the deep trench isolation on the charge collection dynamics associated with ion strikes. Calibrated, full 3D ion strike TCAD simulations are employed to explain the results, revealing substantial enhancement of radial charge diffusion for structures implemented with little to no deep trench. Mitigation of charge collection events are found to occur for emitter-center strikes for devices with limited/eliminated DTI with the caveat of larger collection for outside-DTI ion strikes.

The ejection process of triatomic molecular hydrogen ions produced by the interaction of benzene with ultrafast laser pulses of moderate strong intensity (similar to 10(14) W/cm(2)) is studied by means of TOF mass spectrometry. The H(3)(+) formation can only take place through the rupture of two C-H bonds and the migration of hydrogen atoms within the molecular structure. The H(3)(+) fragments are released with high kinetic energy (typically 2-8 eV) and at laser intensities >= 10(14) W/cm(2), well above that required for the double ionization of benzene, suggesting that its formation is taking place within multiply charged parent ions. The relative ejection efficiency of H(3)(+) molecular hydrogen ions with respect to the atomic ones is found to be strongly decreasing as a function of the laser intensity and pulse duration (67-25 fs). It is concluded that the H(3)(+) formation is only feasible within parent molecular precursors of relatively low charged states and before significant elongation of their structure takes place, while the higher multiply charged molecular ions preferentially dissociate into H(+) ions. The ejection of H(2)(+) ions is also discussed in comparison to the production of H(3)(+) and H(+) ions. Finally, by recording the mass spectra of two deuterium label isotopes of benzene (1,2-C(6)H(4)D(2), 1,4-C(6)H(4)D(2)) it is verified that the ejection efficiency of some molecular fragments, such as D(2)H(+), DH(+), is dependent on the specific position of hydrogen atoms in the molecular skeleton prior dissociation. (C) 2009 American Institute of Physics. [doi:10.1063/1.3246832] Journal of Chemical Physics

A beam splitter is one of the most important devices in an optics laboratory because of its handiness and versatility; equivalent devices are found in various quantum systems to couple two subsystems or to interfere them. While it is normal that two independent input fields are superposed at the beam splitter to give correlated outputs, identical Gaussian states interfere there to produce totally independent output fields. We prove that Gaussian states with same the variance are the only states which bring about factorizable output fields., 6 pages, published in PRA

We propose an experiment to directly prove the commutation relation between bosonic annihilation and creation operators, based on the recent experimental success in single-photon subtraction and addition. We devise a single-photon interferometer to realize coherent superpositions of two sequences of photon addition and subtraction. Depending on the interference outcome, the commutation relation is directly proven or a highly nonclassical state is produced. Experimental imperfections are assessed to show that the realization of the scheme is highly feasible., Comment: 4 pages, additional comment included

We performed an experimental and theoretical investigation of Ramsey-type spectroscopy in conjunction with high-order-harmonic generation. The ninth harmonic $(\ensuremath{\lambda}\ensuremath{\simeq}88\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ of a femtosecond Ti:sapphire laser was used to excite a pair of autoionizing states of krypton. The outcome of the ionization process, detected by an ion-mass spectrometer, shows the characteristic quantum interference pattern. The behavior of the fringe contrast was interpreted on the basis of a simple analytical model, which reproduced well the experimental results without any free parameter.

We report the experimental observation of an enhancement in the yield of high-order harmonics using an array of gas jets as the source medium. By comparing the experimental outcome for jet arrays of different spacings with the predicted harmonic intensity in the case of slit sources of equivalent lengths, we clearly show how the periodic modulation of the gas density can improve the harmonic yield. This behavior may attributed to a quasi-phase-matching effect which increases the length of coherent harmonic build-up during propagation by partially counteracting the dephasing induced by free electrons., 4 pages, 3 figures

A new method for analyzing breakdown phenomena and differentiating between damage created by hot electrons and hot holes under impact ionization induced stress within SiGe HBTs is presented. Measurements demonstrate that electrons are more effective than holes for creating impact ionization induced damage under mixed-mode stress. Lucky electrons and lucky holes can be directly observed using this approach, and the induced hot carrier current yields important insight into understanding reliability of SiGe HBTs under aggressive stress.

We demonstrate the generation of multi-photon quantum states of light by cavity-enhanced parametric down-conversion in the high-repetition-rate pulsed regime. An external enhancement cavity resonant with the spectral comb of modes of a mode-locked pump laser provides a coherent build-up of the pump intensity and greatly enhances the parametric gain without sacrificing its high repetition rate and comb structure. We probe the parametric gain enhancement by the conditional generation and tomographic analysis of two-photon Fock states. Besides its potential impact to efficiently generate highly-nonclassical or entangled multi-photon states in many existing experimental setups, this scheme opens new and exciting perspectives towards the combination of quantum and comb technologies for enhanced measurements and advanced quantum computation protocols., Comment: 5 pages 3 figures; updated with major additions, added references, and changed title. Accepted for publication in Physical Review A

A quantum state is nonclassical if its Glauber-Sudarshan P function fails to be interpreted as a probability density. This quantity is often highly singular, so that its reconstruction is a demanding task. Here we present the experimental determination of a well-behaved P function showing negativities for a single-photon-added thermal state. This is a direct visualization of the original definition of nonclassicality. The method can be useful under conditions for which many other signatures of nonclassicality would not persist., Comment: 4 pages, 4 figures

We evaluate the nuclear fusion rates in the excited vibrational states of molecules of hydrogen isotopes. The ground state fusion rate is increased by about eight orders of magnitude but even in the most favorable situation it is out of any possible experimental test. We discuss the effects due to the nuclear potential in different hyperfine states, and the improvements attainable using coherent states and a solid phase.

We quantitatively assess, for the first time, the capabilities of SiGe HBTs fabricated on thin-film SOI for emerging high-temperature circuit applications. The dc and ac performance of both fully-depleted and partially-depleted SiGe HBTs-on-SOI are measured up to a temperature of 330degC (for dc) and 200degC (for ac). Gummel characteristics, current gain, and output characteristics are reported. M-l is used to investigate how collector doping affects the device behavior at high temperatures. We demonstrate that despite the harsh conditions imposed by high-temperature operation, SiGe HBTs-on-SOI maintain adequate performance for many applications for temperatures in the 200-300degC range.

We report, for the first time, the low frequency noise characteristics of both fully- and partially-depleted SiGe HBTs-on- SOI, both in forward and inverse modes of operation. These SiGe HBTs on thin-film SOI are then compared with bulk SiGe HBTs in order to evaluate how the fundamentally different device structure affects 1/f noise performance. In addition, the impact of substrate voltage, collector doping, and temperature on low-frequency noise is investigated.

The first direct measurement of the atomic dipole phase in high-order harmonic generation obtained by an interferometric technique in the extreme ultraviolet (XUV) is reported. The effects associated with both the main quantum paths involved in the emission of a given plateau harmonic are investigated and compared with the expectations of the semi-classical model, which offers a very simple physical picture for the understanding of the involved electronic dynamics.

We report the experimental realization and tomographic analysis of novel quantum light states obtained by exciting a classical thermal field by a single photon. Such states, although completely incoherent, possess a tunable degree of quantumness which is here exploited to put to a stringent experimental test some of the criteria proposed for the proof and the measurement of state non-classicality. The quantum character of the states is also given in quantum information terms by evaluating the amount of entanglement that they can produce., Comment: 7 pages, 6 figures, accepted for publication in Phys. Rev. A

One of the most important and sometimes controversial stages of the conservation process is surface cleaning: decisions have to be made regarding partial or complete removal of varnish. Technical considerations include selection of a method that allows a great deal of control in the cleaning process, so that undesired layers can be removed without damage to the underlying ones. Traditional cleaning methods include mechanical or chemical removal, and restorers and conservators work would be considerably helped by the knowledge of the varnish thickness. Up to now thickness measurement has been performed in an invasive way by means of stratigraphy, a well known painting structure investigation technique since half a century. In this work we present an application of Optical Coherence Tomography (OCT), a well-established technique for biomedical applications, for non-destructive measuring of the varnish film thickness during the cleaning process of an ancient painting, the Ritratto Trivulzio by Antonello da Messina. OCT images of three differently cleaned areas on the painting surface were acquired and the results were compared with a spectral characterization of the same areas.

We propose focusing by a Fresnel zone plate into a pinhole as a cost-efficient, rugged component for wavelength selection in femtosecond pulses. We show measurements of the frequency selectivity of a Fresnel zone plate for an ultra-broadband supercontinuum pulse. We verify that our zone plate does not considerably stretch the 65 fs laser pulses in time.

We report the generation of thermal light states manipulated by the controlled addition or subtraction of single photons. A full tomographic analysis is used to characterize the resulting states and study conditions for nonclassicality.

We characterize a polarization-entangled photon source based on femtosecond pulsed parametric downconversion in a periodically poled chi((2)) medium. Employing a Sagnac interferometer, we prepared different quantum states aiming at future investigations in quantum information and on the foundations of quantum mechanics. In this work we demonstrate the controlled generation of unbalanced entangled states, rather than the usual maximally entangled ones, by tuning the polarization of the system's pumping field. (C) 2015 Optical Society of America

We discuss some of the main features of a recently-generated form of hybrid entanglement between discrete- and continuous-variable states of light. Ideally, such a kind of entanglement should involve single-photon and coherent states as key representatives of the respective categories of states. Here we investigate the characteristics and limits of a scheme that, relying on a superposition of photon-creation operators onto two distinct modes, realizes the above ideal form of hybrid entanglement in an approximate way.

A comprehensive investigation of reliability issues in both fully-depleted and partially-depleted SiGe HBTs-on-SOI is presented. The devices were subjected to "mixed-mode" stress at 300 K and at 77 K, and we have analyzed the changes in base current IB, collector resistance RC, M-1, and AC performance. A comparison of mixed-mode stress to conventional reverse EB bias stress is also made, and significant differences are observed. The thermal resistance Rth of the devices is extracted over the 50 K ? 300 K range.

We present a review of our recent studies concerning remotely prepared entangled bits (ebits) made of a single photon coherently delocalized between two well-separated temporal modes (or time bins). The preparation scheme represents a remotely tunable source for tailoring arbitrary ebits, whether maximally or non-maximally entangled, which is highly desirable for applications in quantum information technology. The remotely prepared ebit is analyzed by performing both single-mode and two-mode homodyne tomography with the ultra-fast balanced homodyne detection scheme recently developed in our lab. Beside the non-classical behavior typical of single-photon Fock states (negative values around the origin), the reconstructed two-mode Wigner function is found to be characterized by an intriguing phase and by correlations between the two distant time bins sharing the single photon.

Conditional preparation in the process of parametric down-conversion and an ultrafast time-domain homodyne tomography technique have been used for the generation and the complete analysis of novel quantum states of light.

Time-domain balanced homodyne detection is performed on two well-separated temporal modes sharing a single photon. The reconstructed density matrix of the two-mode system is used to prove and quantify its entangled nature, while the Wigner function is employed for an innovative tomographic test of Bell's inequality based on the theoretical proposal by Banaszek and Wodkiewicz [Phys. Rev. Lett. 82, 2009 (1999)]. Provided some auxiliary assumptions are made, a clear violation of Banaszek-Bell's inequality is found., Comment: 7 pages, 3 figures: revised version with additional material; accepetd for publication in Phys. Rev. A

We propose and experimentally verify a novel method for the remote preparation of entangled bits (ebits) made of a single-photon coherently delocalized in two well-separated temporal modes. The proposed scheme represents a remotely tunable source for tailoring arbitrary ebits, whether maximally or non-maximally entangled, which is highly desirable for applications in quantum information technology. The remotely prepared ebit is studied by performing homodyne tomography with an ultra-fast balanced homodyne detection scheme recently developed in our laboratory., Comment: 4 pages, 4 figures, accepted for publication on Phys. Rev. Lett

We report the first direct measurements of the atomic dipole phase in the process of high-order harmonic generation. Differently from previously reported studies based on frequency chirp measurements, we use extreme ultraviolet interferometry as the most natural and direct way to measure phase shifts. Our approach has the important advantage of allowing us to investigate the effects associated to both the main quantum paths involved in the emission of a particular harmonic, thus offering a particularly clear and simple picture of the underlying electronic dynamics.

We report the interferometric measurement of the atomic dipole phase of high-order harmonics generated in noble gases. The contributions of both the main electronic quantum paths predicted by a simple semi-classical model are investigated for the first time in a direct and complete way.

We present a novel X-ray Fluorescence (XRF) spectrometer based on a ring-shaped monolithic array of silicon drift detectors (SDDs) with a hole laser-cut in the center and we show some examples of its application in elemental mapping analyzes. The X-ray excitation beam, focused by a polycapillary X-ray lens in a small and intense spot, reaches the sample going through the central hole of the detector chip. This geometry allows the collection of a large fraction of the fluorescence emitted by the sample and the reduction of the distance between the sample and the detector and, therefore of air absorption. These features, together with the high detection rate of the SDDs shorten the scanning time in elemental mapping. Some application examples of the new spectrometer in different research fields, from archaeometry to biology, are shown. Moreover, the paper introduces a new topology of the multi-element detector based on four SDDs monolithically integrated in a Silicon chip and surrounding a hole cut in its center. The structure of the four SDDs has been specifically designed to obtain very high energy-resolution and peak-to-background ratio. The first experimental results obtained with this detector are presented. It will equip a future version of the XRF spectrometer.

Treatment of the octahedral Ru(II) complex [trans,cis,cis-RuCl(2)(DMSO-O)(2)(CO)(2)] with an equimolar amount of 5,10-bis(3'-pyridyl)-15,20-diphenylporphyrin (3'-cis-DPyP) yielded, upon selective replacement of the DMSO ligands, the neutral 2 + 2 metallacycle 2. NMR spectroscopy provided unambiguous evidence that only one highly symmetrical species, in which the two chromophores are held in a slipped cofacial arrangement by the external Ru(II) metal fragments, exists in solution. The unprecedented geometry of 2, and of the fully zincated analogue 2a, were confirmed in the solid state by X-ray structural investigations. The spatial arrangement of the two parallel chromophores in 2, with an interplanar distance of 4.18 A and a lateral offset (center-to-center distance) of 9.82 A, is reminiscent of those of the special pair of bacteriophylls in the reaction centers and of adjacent B850 units in the LH2 light-harvesting antenna systems of photosynthetic bacteria. For comparison, the X-ray structure of the corresponding metallacycle with 4'-cis-DPyP, 1a, is also reported. In 1a, the two porphyrins have an almost perfect coplanar arrangement. The semi-zincated metallacycles 1b and 2b, in which only one of the two chromophores bears an inner zinc atom, were prepared from 1 and 2, respectively, and isolated in pure form. Detailed photophysical investigations of the above porphyrin assemblies were performed. In particular, very fast photoinduced intercomponent energy transfer processes from the zinc porphyrin to the free-base unit were detected in the semi-metalated derivatives 1b and 2b (time constants: 14 and 12 ps, respectively).

A comprehensive investigation of substrate bias effects on device performance, thermal properties, and reliability of vertical SiGe HBTs fabricated on CMOS-compatible, thin-film SOI, is presented for the first time. Calibrated 2D MEDICI simulations are used to support our explanations, and the resultant device design trade-offs encountered in building SiGe HBTs on thin-film SOI are quantitatively assessed.

Simple experiments, set up to investigate how the coherence properties of short and intense laser pulses are transferred to radiation generated in extremely nonlinear interactions with matter, have given access to a wealth of new information and have allowed unexpected advances in several different fields. Here, we review some of these experiments and discuss their implications for the development of new methods in ultra-high spectral and temporal resolution studies of matter.

M. Bellini,1,2 C. Lynga,3 A. Tozzi,4 M. B. Gaarde,3,5 T. W. Hansch,2,4,6 A. L’Huillier,3 and C.-G. Wahlstrom3 1European Laboratory for Non Linear Spectroscopy (L.E.N.S.), Largo E. Fermi, 2, I-50125 Florence, Italy 2Istituto Nazionale di Fisica della Materia, INFM, Florence, Italy 3Department of Physics, Lund Institute of Technology, P.O. Box 118, S-221 00 Lund, Sweden 4Department of Physics, University of Florence, Largo E. Fermi, 2, I-50125 Florence, Italy 5Niels Bohr Institute, Orsted Laboratory, 2100 Copenhagen, Denmark 6Max-Planck-Institut fur Quantenoptik, P.O. Box 1513, D-85740 Garching, Germany (Received 19 December 1997)

A new class of non-classical light states has been experimentally generated and their complete phase-space characterization has been achieved by quantum homodyne tomography. Such states are produced by the action of the photon creation operator on a coherent light field and are thus the result of the elementary excitation process of a classical field by a single quantum. Being intermediate between a single-photon Fock state and a coherent one, they offer the unique opportunity to closely follow the smooth evolution between the particle-like and the wave-like behavior of the light field.

When a single quantum of electromagnetic field excitation is added to the same spatio-temporal mode of a coherent state, a new field state is generated that exhibits intermediate properties between those of the two parents. Such a single-photon-added coherent state is obtained by the action of the photon creation operator on a coherent state and can thus be regarded as the result of the most elementary excitation process of a classical light field. Here we present and describe in depth the experimental realization of such states and their complete analysis by means of a novel ultrafast, time-domain, quantum homodyne tomography technique clearly revealing their non-classical character., 9 pages, 9 figures. Accepted for publication in Phys. Rev. A

We present the experimental generation of a new class of non-classical light states and their complete phase-space characterization by quantum homodyne tomography. These states are the result of the most elementary amplification process of classical light fields by a single quantum of excitation and can be generated by the process of stimulated emission of a single photon in the mode of a coherent state. Being intermediate between a single-photon Fock state and a coherent one, they offer the unique opportunity to closely follow the smooth evolution between the particle-like and the wave-like behavior of the light field and to witness the gradual change from the spontaneous to the stimulated regimes of light emission.

In the last few years many non-destructive techniques have entered the field of painting conservation, and most of them are routinely applied to study and monitoring the painting status. Among them optical techniques are by now widely diffused and extremely well received because of their effectiveness and safety, nevertheless none of them is suitable for a quantitative characterization of varnish. One of the most important and often controversial stages of painting restoration is the surface cleaning process up to now being carried out without any tool to measure the actual varnish thickness but microscope observation of micro-detach. In this work we present an application of Optical Coherence Tomography to non-destructive diagnostics of artwork: the potentiality of this technique is demonstrated by measuring the thickness of the varnish layer in a fragment of a nineteenth-century oil painting.

Monolithic arrays of Silicon Drift Detectors (SDDs) have been employed successfully in X-ray spectroscopy and /spl gamma/-ray imaging applications. Thanks to the low electronics noise achieved at short shaping time, the SDD is an ideal device for high-resolution and high-rate X-ray spectroscopy experiments at synchrotron sources. Moreover, small monolithic arrays of SDDs have also been used as photodetector of the scintillation light in a first prototype of Anger Camera for /spl gamma/-ray imaging characterized by an intrinsic resolution better than 0.3 mm. In this work we present a new large-area monolithic array of Silicon Drift Detectors. It consists of a single chip composed by 77 single hexagonal units, each one with a front-end JFET integrated in its center, arranged in a honeycomb configuration. Each SDD unit has an active area of 8.7 mm/sup 2/, for a total active area of the device of 6.7 cm/sup 2/. The linear dimensions of the active area are approximately 29/spl times/26 mm/sup 2/. It represents the largest monolithic array of SDDs with on-chip JFETs produced up to now for X-ray and /spl gamma/-ray detection. The results achieved in the experimental characterization of a first prototype of the detector array are presented. They include also the preliminary X-ray spectroscopy characterization of the SDD's units. The energy resolution measured at 6 keV with the single unit of the array is of 142eV at -10/spl deg/C.

We describe the series of experiments that led to the development of the Ramsey technique for achieving high-resolution atomic spectroscopy in the extreme ultraviolet with high-order harmonics. We start with a demonstration of phase coherence in the harmonic generation process, then, we illustrate the appearance of spectral interference fringes in the case of collinear, time-delayed harmonic pulses, and we finally present the first demonstration of a Ramsey technique that is based on pairs of time-delayed and phase-coherent harmonic pulses and that is used for the study of the excited states of krypton.

Non-destructive optical testing techniques are widely used in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for non-destructive investigations of paintings are available. Optical Coherence Tomography (OCT) is a non invasive technique allowing cross sectional imaging of partially transparent or scattering tissue which is now well-established for biomedical applications. Particularly, the OCT techniques allow evaluating multilayer tissues. Being applied to painting diagnostics, the OCT gives a possibility to measure the actual varnish thickness that is very important in painting restoration by the cleaning process. Because of complicated local structure of layers and light scattering, noise-immune signal processing methods should be used. In the paper, the Kalman filtering method involving random fringe model applied to the OCT signals is investigated and compared with conventional fringe amplitude demodulation method. Experimental results obtained when recovering OCT tomograms of paintings are presented and discussed.

This paper describes a novel x-ray fluorescence spectrometer designed for elemental mapping applications. The spectrometer is based on a ring-shaped monolithic array of silicon drift detectors (SDDs) with a hole in the center. The coaxial x-ray excitation beam, focused by a polycapillary x-ray lens, reaches the sample after passing through the central hole. This geometry optimizes the useful solid angle for collecting the fluorescence from the sample, while the optics maximizes the photon density in the excitation spot. These features, together with the very high detection rate of SDDs, allow a high scanning rate in elemental mapping to be achieved. Moreover, the spectroscopic resolution of SDDs (cooled by thermoelectric Peltier elements) is comparable to that of the classical Si(Li) liquid nitrogen-cooled detectors. Several examples of applications of the novel spectrometer in various fields, from archeometry to biology, are presented. This paper introduces also a new multi-element detector based on SDDs whose structure has been specifically optimized for very high resolution and very fast elemental mapping.

A single-photon Fock state has been generated by means of conditional preparation from a two-photon state emitted in the process of spontaneous parametric down-conversion. A recently developed high-frequency homodyne tomography technique has been used to completely characterize the Fock state by means of a pulse-to-pulse analysis of the detectors' difference photocurrent. The density matrix elements of the generated state have been retrieved with a final detection efficiency of about 57%. A comparison has been performed between the phase-averaged tomographic reconstructions of the Wigner function as obtained from the measured density-matrix elements and from a direct Abel transform of the homodyne data. The ability of our system to work at the full repetition rate of the pulsed laser (82 MHz) substantially simplifies the detection scheme, allowing for more ``exotic'' quantum states to be generated and analyzed., 7 pages, 5 figures

We present an experimental and theoretical analysis of the energy-time entanglement properties of a two-photon state generated by pulsed spontaneous parametric down-conversion. Different methods of spectral or temporal shaping of one of the two photons have allowed the observation of nonlocal modulations in the autocorrelation or in the spectrum of the other, by coincidence measurements. Either a monochromator or etalon filters have been used to shape the idler photon while observing the conditioned signal autocorrelation with a Michelson interferometer. Alternatively, the unbalanced interferometer has been used to shape the signal photon while measuring the conditioned idler spectrum with the monochromator. The role of the pump spectrum has been investigated by shaping it with additional filters. A theoretical treatment has allowed us to completely describe all the observed features as a function of the different experimental parameters.

We experimentally show the selective control of fourth‐order recurrent interferences in a modified version of a Hong‐Ou‐Mandel interferometer using comb‐like two‐photon states. The comb spectral/temporal structure is obtained by inserting an etalon cavity in the signal path of an entangled photon pair obtained by pulsed spontaneous parametric down‐conversion.

We demonstrate full selective control over the constructive or destructive character of fourth-order recurring interferences in a modified version of a HOM interferometer using comb-like two-photon states. The comb spectral/temporal structure is obtained by inserting an etalon cavity in the signal path of an entangled photon pair obtained by pulsed spontaneous parametric down-conversion. Both a simple qualitative discussion and a complete theoretical derivation are used to explain and analyze the experimental data., Comment: 4 pages, 4 figures. Revised version, to appear in Physical Review A

We present an experiment where Ramsey-type spectroscopy is applied to autoionizing states of krypton by using the ninth harmonic (88 nm) of a femtosecond Ti:sapphire laser. The ionization process, detected by an electron-energy spectrometer, shows the characteristic quantum interference pattern. The behavior of the fringe contrast compares favorably with a simple essential-state model, whose parameters have been taken from the literature. The experiment shows the feasibility of high-resolution spectroscopy in the extreme ultraviolet by using high-order laser harmonics.

The realization of hybrid entanglement between a microscopic (quantum) and a macroscopic (classical) system, in analogy to the situation of the famous Schrödinger's cat paradox, is an important milestone, both from the fundamental perspective and for possible applications in the processing of quantum information. The most straightforward optical implementation of this condition is that of the entanglement between a single-photon and a coherent state. In this work, we describe the first step towards the generation of this type of hybrid entanglement from the experimental perspective.

Organometallic fuel cells catalyze the selective electrooxidation of renewable diols, simultaneously providing high power densities and chemicals of industrial importance. It is shown that the unique organometallic complex [Rh(OTf)(trop(2)NH)(PPh3)] employed as molecular active site in an anode of an OMFC selectively oxidizes a number of renewable diols, such as ethylene glycol, 1,2-propanediol (1,2-P), 1,3-propanediol (1,3-P), and 1,4-butanediol (1,4-B) to their corresponding mono-carboxylates. The electrochemical performance of this molecular catalyst is discussed, with the aim to achieve cogeneration of electricity and valuable chemicals in a highly selective electrooxidation from diol precursors.

not Available.