Transmittivity measurements by means of squeezed vacuum light

A method for measuring the transmittivity of optical samples by using squeezed--vacuum radiation is illustrated. A squeezed vacuum field generated by a below--threshold optical parametric oscillator is propagated through a nondispersive medium and detected by a homodyne apparatus. The variance of the detected quadrature is used for measuring the transmittivity. With this method it is drastically reduced the number of photons passing through the sample during the measurement interval. The results of some tests are reported.Comment: 14 pages, 8 figure

Homodyne extimation of quantum states purity by exploiting covariant uncertainty relation

We experimentally verify uncertainty relations for mixed states in the tomographic representation by measuring the radiation field tomograms, i.e. homodyne distributions. Thermal states of single-mode radiation field are discussed in details as paradigm of mixed quantum state. By considering the connection between generalised uncertainty relations and optical tomograms is seen that the purity of the states can be retrieved by statistical analysis of the homodyne data. The purity parameter assumes a relevant role in quantum information where the effective fidelities of protocols depend critically on the purity of the information carrier states. In this contest the homodyne detector becomes an easy to handle purity-meter for the state on-line with a running quantum information protocol.Comment: accepted for publication into Physica Script

Amendable Gaussian channels:restoring entanglement via a unitary filter

We show that there exist Gaussian channels which are amendable. A channel is amendable if when applied twice is entanglement breaking while there exists a unitary filter such that, when interposed between the first and second action of the map, prevents the global transformation from being entanglement breaking [Phys. Rev. A 86, 052302 (2012)]. We find that, depending on the structure of the channel, the unitary filter can be a squeezing transformation or a phase shift operation. We also propose two realistic quantum optics experiments where the amendability of Gaussian channels can be verified by exploiting the fact that it is sufficient to test the entanglement breaking properties of two mode Gaussian channels on input states with finite energy (which are not maximally entangled).Comment: 9 pages, 6 figure

Exploitation of multi-objective optimization in retrofit analysis: a case study for the iron and steel production

Abstract Over the past few decades the issues related to the energy consumption and the climate change have been increased and they have achieved a significant position on the sustainability agenda of the steel industry. Steel production is among the largest energy-intensive industrial processes in the world, as well as one of the most important CO 2 emission sources. However, the major role of steel utilisation in the modern society is undeniable. The challenges of industrial energy systems aim at achieving CO 2 minimization, without neglecting energy efficiency as well as the development of effective models and strategies for process optimization. The application of Process Integration (PI) methods to the integrated steelmaking route, aims at achieving a reduction in the CO 2 emission by optimizing material and energy systems. The work presented in this paper is devoted to the development of a model for optimal exploitation of energy resources and by-products in integrated steelworks through application of multi-objective optimisation techniques. Cases of exploitation of the system within the management of the process gases are presented in a retrofit scenario and compared to the case of nominal operation

Trapped Ions in Laser Fields: a Benchmark for Deformed-Quantum Oscillators

Some properties of the non--linear coherent states (NCS), recognized by Vogel and de Matos Filho as dark states of a trapped ion, are extended to NCS on a circle, for which the Wigner functions are presented. These states are obtained by applying a suitable displacement operator $D_{h}(\alpha)$ to the vacuum state. The unity resolutions in terms of the projectors $| \alpha, h> < \alpha, h|$. $D_{h}(\alpha)$ is also used for introducing the probability distribution funtion $\rho_{A,h}(z)$ while the existence of a measure is exploited for extending the P-representation to these states. The weight of the n-th Fock state of the NCS relative to a trapped ion with Lamb-Dicke parameter $\eta ,$ oscillates so wildly as $n$ grows up to infinity that the normalized NCS fill the open circle $\eta ^{-1}$ in the complex $\alpha$-plane. In addition this prevents the existence of a measure including normalizable states only. This difficulty is overcome by introducing a family of deformations which are rational functions of n, each of them admitting a measure. By increasing the degree of these rational approximations the deformation of a trapped ion can be approximated with any degree of accuracy and the formalism of the P-representation can be applied

Emergencies in patients with advanced cancer followed at home.

Abstract CONTEXT: Patients with advanced cancer stay at home for most of their time, and acute problems may occur during home care. Caregivers may call medical services for an emergency, which can result in patients being admitted to the hospital. No data exist on emergencies in patients followed by a home care team. OBJECTIVES: The aim of this multicenter prospective study was to assess the frequency, reasons for, and subsequent course of emergency calls for patients followed at home by a palliative care team. METHODS: A consecutive sample of patients admitted to home care programs was surveyed for a period of seven months. Epidemiological data, and characteristics of emergency calls and outcomes, as well as environmental situations were recorded. RESULTS: Six hundred eighty-nine patients were surveyed; 118 patients (17.1% of the total number of patients surveyed) made one emergency call, 23 made two calls, and four made three calls for a total number of 176 emergency calls. The mean age was 71 years (standard deviation [SD] 13), and the mean Karnofsky status the day before the emergency call was 38 (SD 14). The mean time from admission to the first emergency call was 38.4 days (SD 67), and the mean time from the first emergency call to death was 17.5 days (SD 41.5). No differences were found for age, diagnosis, gender, duration of assistance, and survival between patients making emergency calls and those who did not make a call during an emergency. Twenty-three patients were managed by phone, and 122 were visited at home for the emergency. Calls were prevalently recorded on weekdays and were primarily made by relatives. The most frequent reasons for calling were dyspnea, pain, delirium, and loss of consciousness. Calls were considered justified by home care physicians in most cases. The mean number of relatives present during the emergency home visit was 2.2 (SD 1.5). The intervention was mainly pharmacological and considered satisfactory in the majority of cases. CONCLUSION: Emergency calls are relatively frequent in patients followed at home by a palliative care team. Phone consultation or intervention at home may avoid inappropriate hospital admission

Full characterization of Gaussian bipartite entangled states by a single homodyne detector

We present the full experimental reconstruction of Gaussian entangled states generated by a type--II optical parametric oscillator (OPO) below threshold. Our scheme provides the entire covariance matrix using a single homodyne detector and allows for the complete characterization of bipartite Gaussian states, including the evaluation of purity, entanglement and nonclassical photon correlations, without a priori assumptions on the state under investigation. Our results show that single homodyne schemes are convenient and robust setups for the full characterization of OPO signals and represent a tool for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR

Optical tomography of Fock state superpositions

We consider optical tomography of photon Fock state superpositions in connection with recent experimental achievements. The emphasis is put on the fact that it suffices to represent the measured tomogram as a main result of the experiment. We suggest a test for checking the correctness of experimental data. Explicit expressions for optical tomograms of Fock state superpositions are given in terms of Hermite polynomials. Particular cases of vacuum and low photon-number state superposition are considered as well as influence of thermal noise on state purity is studied.Comment: 5 pages, 2 figure

Optical response of a misaligned and suspended Fabry-Perot cavity

The response to a probe laser beam of a suspended, misaligned and detuned optical cavity is examined. A five degree of freedom model of the fluctuations of the longitudinal and transverse mirror coordinates is presented. Classical and quantum mechanical effects of radiation pressure are studied with the help of the optical stiffness coefficients and the signals provided by an FM sideband technique and a quadrant detector, for generic values of the product $\varpi \tau$ of the fluctuation frequency times the cavity round trip. A simplified version is presented for the case of small misalignments. Mechanical stability, mirror position entanglement and ponderomotive squeezing are accommodated in this model. Numerical plots refer to cavities under test at the so-called Pisa LF facility.Comment: 14 pages (4 figures) submitted to Phys. Rev.