Theoretical Setting of Inner Reversible Quantum Measurements

We show that any unitary transformation performed on the quantum state of a closed quantum system, describes an inner, reversible, generalized quantum measurement. We also show that under some specific conditions it is possible to perform a unitary transformation on the state of the closed quantum system by means of a collection of generalized measurement operators. In particular, given a complete set of orthogonal projectors, it is possible to implement a reversible quantum measurement that preserves the probabilities. In this context, we introduce the concept of "Truth-Observable", which is the physical counterpart of an inner logical truth.Comment: 11 pages. More concise, shortened version for submission to journal. References adde

A Minimal Model for Quantum Gravity

We argue that the model of a quantum computer with N qubits on a quantum space background, which is a fuzzy sphere with n=2^N elementary cells, can be viewed as the minimal model for Quantum Gravity. In fact, it is discrete, has no free parameters, is Lorentz invariant, naturally realizes the Holographic Principle, and defines a subset of punctures of spin networks' edges of Loop Quantum Gravity labelled by spins j=2^(N-1)-1/2. In this model, the discrete area spectrum of the cells, which is not equally spaced, is given in units of the minimal area of Loop Quantum Gravity (for j=1/2), and provides a discrete emission spectrum for quantum black holes. When the black hole emits one string of N bits encoded in one of the n cells, its horizon area decreases of an amount equal to the area of one cell.Comment: 11 pages, 4 figures, Contributed paper at DICE 2004, 1-4 September 2004, Piombino, Italy minor changes, misprints correcte

Study of cosmic ray showers front and time structure with ARGO-YBJ

ARGO-YBJ is a full coverage Extensive Air Showe

Temperature effect on RPC performance in the ARGO-YBJ experiment

The ARGO-YBJ experiment has been taking data for nearly 2 years. In order to monitor continuously the performance of the Resistive Plate Chamber detectors and to study the daily temperature effects on the detector performance, a cosmic ray muon telescope was setup near the carpet detector array in the ARGO-YBJ laboratory. Based on the measurements performed using this telescope, it is found that, at the actual operating voltage of 7.2kV, the temperature effect on the RPC time resolution is about 0.04ns/degrees C and on the particle detection efficiency is about 0.03%/degrees C. Based on these figures we conclude that the environmental effects do not affect substantially the angular resolution of the ARGO-YBJ detector