Cloning a Qutrit

We investigate several classes of state-dependent quantum cloners for three-level systems. These cloners optimally duplicate some of the four maximally-conjugate bases with an equal fidelity, thereby extending the phase-covariant qubit cloner to qutrits. Three distinct classes of qutrit cloners can be distinguished, depending on two, three, or four maximally-conjugate bases are cloned as well (the latter case simply corresponds to the universal qutrit cloner). These results apply to symmetric as well as asymmetric cloners, so that the balance between the fidelity of the two clones can also be analyzed.Comment: 14 pages LaTex. To appear in the Journal of Modern Optics for the special issue on "Quantum Information: Theory, Experiment and Perspectives". Proceedings of the ESF Conference, Gdansk, July 10-18, 200

Momentum conservation and correlation analyses in heavy-ion collisions at ultrarelativistic energies

Global transverse-momentum conservation induces correlations between any number of particles, which contribute in particular to the two- and three-particle correlations measured in heavy-ion collisions. These correlations are examined in detail, and their importance for studies of jets and their interaction with the medium is discussed.Comment: 5 pages, 2 figures. v2: corrected typos and added a paragrap

Flexible quantum circuits using scalable continuous-variable cluster states

We show that measurement-based quantum computation on scalable continuous-variable (CV) cluster states admits more quantum-circuit flexibility and compactness than similar protocols for standard square-lattice CV cluster states. This advantage is a direct result of the macronode structure of these states---that is, a lattice structure in which each graph node actually consists of several physical modes. These extra modes provide additional measurement degrees of freedom at each graph location, which can be used to manipulate the flow and processing of quantum information more robustly and with additional flexibility that is not available on an ordinary lattice.Comment: (v2) consistent with published version; (v1) 11 pages (9 figures

Quantum spin glass and the dipolar interaction

Systems in which the dipolar energy dominates the magnetic interaction, and the crystal field generates strong anisotropy favoring the longitudinal interaction terms, are considered. Such systems in external magnetic field are expected to be a good experimental realization of the transverse field Ising model. With random interactions this model yields a spin glass to paramagnet phase transition as function of the transverse field. Here we show that the off-diagonal dipolar interaction, although effectively reduced, destroys the spin glass order at any finite transverse field. Moreover, the resulting correlation length is shown to be small near the crossover to the paramagnetic phase, in agreement with the behavior of the nonlinear susceptibility in the experiments on \LHx. Thus, we argue that the in these experiments a cross-over to the paramagnetic phase, and not quantum criticality, was observed.Comment: To appear in Phys. Rev. Let

Error Analysis of Phonetic Fossilization Uttered by English Department Students University of PGRI Semarang

Penelitian ini bertujuan untuk menentukan tipe dan latar belakang fosilisasi fonetik yang diucapkan oleh mahasiswa semester 5 Pendidikan Bahasa Inggris di Universitas PGRI Semarang tahun 2014/2015. Penelitian ini menggunakan desain penelitian deskriptif dengan data kualitatif. Populasi dari penelitian ini adalah para mahasiswa semester 5 yang mengambil mata kuliah English Phonology dengan jumlahmahasiswa 200. Sampel penelitian adalah kelas 5E, kelas yang paling aktif dan dominan.Hasil penelitian menunjukkan bahwa hanya 15% kata di dalam kuesioner penelitian yang berhasil dilafalkan dengan baik oleh para responden. Itu artinya bahwa fosilisasi fonetik dilakukan lebih dari 75% responden. Tipe kesalahan yang dibuat adalah tipe fosilisasi fonetik baik dalam kategori perseorangan maupun kelompok, sementara itu alasan-alasan mereka melakukan kesalahan adalah; 1)Simbol fonetik yang masih tidak familier bagi mahasiswa semester. 2) Terdapat habituasi dan kebiasaan-kebiasaan yang merujuk pada dua faktor: internal dan eksternal. Faktor internalnya adalah mahasiswa itu sendiri, yang berarti motivasi untuk belajar dan hasrat untuk lebih dalam mempelajari simbol -simbol fonetik. Faktor eksternalnya merujuk pada proses pembelajaran dan sudut pandang dosen. 3) Metode yang digunakan oleh para dosen pengampu mata kuliah English Phonology and Pronounciation. Masalah ini harus diturunkan karena 90% dari mahasiswa menyatakan di dalam wawancara bahwa mereka sangat tertarik dengan subjek ini danjuga menyatakan bahwa para dosen tidak memberikan tekanan, namun faktanya persentase kesalahan dalam pelafalan di atas rata-rata.Berdasarkan pada hasil-haasil ini, peneliti memberika saran sebagai berikut; 1) Permasalahan ini menjadi tugas bagi seluruh dosen bahasa Inggris, tidak hanya dosen yang mengajar mata kuliah English Phonology and Pronunciation. 2) Simbolsimbol fonetik harus diterapkan secara intensif dan integral sehingga para mahasiswa dapat familier dengan simbol-simbol tersebut. 3) Kebutuhan akan penelitian lebih lanjut yang terkait dengan metode-metode yang digunakan oleh para dosen

Further Criteria for the Existence of Steady Line-Driven Winds

In Paper I, we showed that steady line-driven disk wind solutions can exist by using "simple" models that mimic the disk environment. Here I extend the concepts introduced in Paper I and discuss many details of the analysis of the steady/unsteady nature of 1D line-driven winds. This work confirms the results and conclusions of Paper I, and is thus consistent with the steady nature of the 1D streamline line-driven disk wind models of Murray and collaborators and the 2.5D line-driven disk wind models of Pereyra and collaborators. When including gas pressures effects, as is routinely done in time-dependent numerical models, I find that the spatial dependence of the nozzle function continues to play a key role in determining the steady/unsteady nature of supersonic line-driven wind solutions. I show here that the existence/nonexistence of local wind solutions can be proved through the nozzle function without integrating the equation of motion. This work sets a detailed framework with which we will analyze, in a following paper, more realistic models than the "simple" models of Paper I.Comment: 30 pages, 5 figures, accepted for publication by The Astrophysical Journa

Astrophysical and Dark Matter Interpretations of Extended Gamma-Ray Emission from the Galactic Center

We construct empirical models of the diffuse gamma-ray background toward the Galactic Center. Including all known point sources and a template of emission associated with interactions of cosmic rays with molecular gas, we show that the extended emission observed previously in the Fermi Large Area Telescope data toward the Galactic Center is detected at high significance for all permutations of the diffuse model components. However, we find that the fluxes and spectra of the sources in our model change significantly depending on the background model. In particular, the spectrum of the central Sgr A$^\ast$ source is less steep than in previous works and the recovered spectrum of the extended emission has large systematic uncertainties, especially at lower energies. If the extended emission is interpreted to be due to dark matter annihilation, we find annihilation into pure $b$-quark and $\tau$-lepton channels to be statistically equivalent goodness of fits. In the case of the pure $b$-quark channel, we find a dark matter mass of $39.4\left(^{+3.7}_{-2.9}\rm\ stat.\right)\left(\pm 7.9\rm\ sys.\right)\rm\ GeV$, while a pure$\tau^{+} \tau^{-}$-channel case has an estimated dark matter mass of$9.43\left(^{+0.63}_{-0.52}\rm\ stat.\right)(\pm 1.2\rm\ sys.)\ GeV$. Alternatively, if the extended emission is interpreted to be astrophysical in origin such as due to unresolved millisecond pulsars, we obtain strong bounds on dark matter annihilation, although systematic uncertainties due to the dependence on the background models are significant.Comment: 14 pages, 11 figures; v3: matches version in Phys. Rev.

A new conjecture extends the GM law for percolation thresholds to dynamical situations

The universal law for percolation thresholds proposed by Galam and Mauger (GM) is found to apply also to dynamical situations. This law depends solely on two variables, the space dimension d and a coordinance numberq. For regular lattices, q reduces to the usual coordination number while for anisotropic lattices it is an effective coordination number. For dynamical percolation we conjecture that the law is still valid if we use the number q_2 of second nearest neighbors instead of q. This conjecture is checked for the dynamic epidemic model which considers the percolation phenomenon in a mobile disordered system. The agreement is good.Comment: 8 pages, latex, 3 figures include