9,582 research outputs found
Persistent Homology analysis of Phase Transitions
Persistent homology analysis, a recently developed computational method in
algebraic topology, is applied to the study of the phase transitions undergone
by the so-called XY-mean field model and by the phi^4 lattice model,
respectively. For both models the relationship between phase transitions and
the topological properties of certain submanifolds of configuration space are
exactly known. It turns out that these a-priori known facts are clearly
retrieved by persistent homology analysis of dynamically sampled submanifolds
of configuration space.Comment: 10 pages; 10 figure
Coherent structures in an electron beam
The formation and evolution of coherent structures in a low-energy electron
beam produced in a Malmberg-Penning trap is investigated by means of CCD
diagnostics. The electrons are emitted from a thermionic cathode and their
energy is controlled by an acceleration grid. By varying the spatial
distribution of the energy of emitted electrons, different space charge effects
are observed, as, e. g., a sharp or a gradual transition to a space charge
dominated regime. The variation of the coherent structures along the beam is
studied by varying the electron density or/and the value of the confined
magnetic field. The observed processes are interpreted using a tridimensional
particle-in-cell code which solves the Vlasov-Poisson system in zeroth order
drift approximation.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
Bridging thermodynamics and metrology in non-equilibrium Quantum Thermometry
Single-qubit thermometry presents the simplest tool to measure the
temperature of thermal baths with reduced invasivity. At thermal equilibrium,
the temperature uncertainty is linked to the heat capacity of the qubit,
however the best precision is achieved outside equilibrium condition. Here, we
discuss a way to generalize this relation in a non-equilibrium regime, taking
into account purely quantum effects such as coherence. We support our findings
with an experimental photonic simulation.Comment: 7 pages, 4 figure
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