Protective Measurement-A New Quantum Measurement Paradigm: Detailed Description of the First Realization

We present a detailed description of the experiment realizing for the first time a protective measurement, a novel measurement protocol which combines weak interactions with a "protection mechanism" preserving the measured state coherence during the whole measurement process. Furthermore, protective measurement allows finding the expectation value of an observable, i.e., an inherently statistical quantity, by measuring a single particle, without the need for any statistics. This peculiar property, in sharp contrast to the framework of traditional (projective) quantum measurement, might constitute a groundbreaking advance for several quantum technology related fields

Experimental realization of sub-shot-noise quantum imaging

Properties of quantum states have disclosed new technologies, ranging from quantum information to quantum metrology. Among them a recent research field is quantum imaging, addressed to overcome limits of classical imaging by exploiting spatial properties of quantum states of light . In particular quantum correlations between twin beams represent a fundamental resource for these studies. One of the most interesting proposed scheme exploits spatial quantum correlations between parametric down conversion light beams for realizing sub-shot-noise imaging of the weak absorbing objects, leading ideally to a noise-free imaging. Here we present the first experimental realisation of this scheme, showing its capability to reach a larger signal to noise ratio (SNR) with respect to classical imaging methods. This work represents the starting point of this quantum technology that can have relevant applications, especially whenever there is a need of a low photon flux illumination (e.g. as with certain biological samples)

Spatial and spectral mode selection of heralded single photons from pulsed parametric down-donversion

C1 - Journal Articles RefereedWe describe an experiment in which photon pairs from a pulsed parametric down-conversion (PDC) source were coupled into single-mode fibers with heralding efficiencies as high as 70%. Heralding efficiency or mode preparation efficiency is defined as the probability of finding a photon in a fiber in a definite state, given the detection of its twin. Heralding efficiencies were obtained for a range of down-conversion beam-size configurations. Analysis of spatial and spectral mode selection, and their mutual correlation, provides a practical guide for engineering PDC-produced single photons in a definite mode and spectral emission band. The spectrum of the heralded photons were measured for each beam configuration, to determine the interplay between transverse momentum and spectral entanglement on the preparation efficiency

Theoretical description and experimental simulation of quantum entanglement near open time-like curves via pseudo-density operators

Closed timelike curves are striking predictions of general relativity allowing for time-travel. They are afflicted by notorious causality issues (e.g. grandfather's paradox). Quantum models where a qubit travels back in time solve these problems, at the cost of violating quantum theory's linearity-leading e.g. to universal quantum cloning. Interestingly, linearity is violated even by open timelike curves (OTCs), where the qubit does not interact with its past copy, but is initially entangled with another qubit. Non-linear dynamics is needed to avoid violating entanglement monogamy. Here we propose an alternative approach to OTCs, allowing for monogamy violations. Specifically, we describe the qubit in the OTC via a pseudo-density operator-a unified descriptor of both temporal and spatial correlations. We also simulate the monogamy violation with polarization-entangled photons, providing a pseudo-density operator quantum tomography. Remarkably, our proposal applies to any space-time correlations violating entanglement monogamy, such as those arising in black holes

Banking market consumer loans in the Slovak republic

This paper aims at consumer loans on the banking market in the Slovak republic. It defines legislature related to the topic in the European union, as well as in the Slovak republic. Later on, it concentrates on verification of client data, analyses precontracual information provided to consumers and the portfolio of consumer loans offerd by the Slovak banks

Monitoring cells local temperature variation using nitrogen-vacancy (NV) centers in nanodiamonds

The growing interest in understanding the complex mechanisms that regulate biological processes has prompted the study and the improvement of quantum sensors, potentially capable of detecting a wide class of physical quantities of biological interest. Among the various sensors proposed for biological applications, nitrogen-vacancy (NV) centers in artificial diamond have emerged as a truly promising solution primarily thanks to their excellent bio-compatibility. Such NV sensors can be synthesized of nanometer size. The nanodiamonds can be inserted inside cells and, if properly functionalized, they can be targeted to organelles, such as mitochondria, or ion channels. In addition to the advantages regarding their chemical and structural composition, the NV sensors have distinguished themselves thanks to their sensitivity respect different physical quantity, such as magnetic and electric fields, temperatures and pressures variations. Although the sensitivity achieved by the NV quantum sensors is not yet sufficient to detect the very weak electromagnetic fields generated by biological processes, the thermal variation generated at the cellular level seem at the moment a more attractive field of application. Temperature is an important parameter for the regulation of intracellular processes and its detection is fundamental for a more complete understanding of them. Cellular activity and metabolism can affect the local temperature in cells and pathological conditions such as cancer, Parkinson and Alzherimer's disease can alter it. In this sense, local temperature monitoring within cells is also important for clinical application. Here we will present our experimental setup dedicated to local temperature measurement in neuronal cell cultures. The measurement technique is based on optically detected magnetic resonance (ODMR) with the NV centers in the nanodiamonds, suitably engineered to be sensitive and at the same time biocompatible. We will demonstrate a proof of principle experiment in which we measure the local temperature variation in cultured hippocampal neurons. The temperature sensitivity is 3 K/Hz(1/2). In addition we will show how the nanodiamonds with a size of around 200 nm are internalized by the neurons