We consider a quantum wire double junction system with each wire segment described by a spinless Luttinger model, and study theoretically shot noise in this system in the sequential tunnelling regime. We find that the non-equilibrium plasmonic excitations in the central wire segment give rise to qualitatively different behaviour compared to the case with equilibrium plasmons. In particular, shot noise is greatly enhanced by them, and exceeds the Poisson limit. We show that the enhancement can be explained by the emergence of several current-carrying processes, and that the effect disappears if the channels effectively collapse to one because of fast plasmon relaxation processes, for example.

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PACS. 89.90.+n -Other topics in areas of applied and interdisciplinary physics. PACS. 89.70.+c -Information science. PACS. 05.50.+q -Lattice theory and statistics (Ising, Potts, etc.).Abstract. -A variation of low-density parity check (LDPC) error-correcting codes defined over Galois fields (GF (q)) is investigated using statistical physics. A code of this type is characterised by a sparse random parity check matrix composed of C non-zero elements per column. We examine the dependence of the code performance on the value of q, for finite and infinite C values, both in terms of the thermodynamical transition point and the practical decoding phase characterised by the existence of a unique (ferromagnetic) solution. We find different q-dependence in the cases of C = 2 and C ≥ 3; the analytical solutions are in agreement with simulation results, providing a quantitative measure to the improvement in performance obtained using non-binary alphabets.

We have used ab initio configuration-interaction methods to calculate inner-shell excitations in Ca + and used the resulting calculations to study the 3p-hole photoionization spectrum of Ca + in the photon energy range 25-40 eV. We have identified almost all the peaks in the experimental spectrum of Lyon et al. We also compare our findings with the autoionization spectrum following electron-impact excitation reported by Pejčev et al and the photoionization spectrum obtained by Gottwald et al.

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