Adiabatic dynamics in a spin-1 chain with uniaxial single-spin anisotropy

We study the adiabatic quantum dynamics of an anisotropic spin-1 XY chain across a second order quantum phase transition. The system is driven out of equilibrium by performing a quench on the uniaxial single-spin anisotropy, that is supposed to vary linearly in time. We show that, for sufficiently large system sizes, the excess energy after the quench admits a non trivial scaling behavior that is not predictable by standard Kibble-Zurek arguments for isolated critical points or extended critical regions. This emerges from a competing effect of many accessible low-lying excited states, inside the whole continuous line of critical points.Comment: 17 pages, 8 figures, published versio

Monitoraggio ambientale mediante l'impiego di suoli e di muschi per le discariche di Rio Riazzone, Rio Vigne e Poiatica di Reggio Emilia

The purposes of this environmental monitoring was to estimate the concentrations of the elements (Al, As, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Ti, V, Zn, Pt and Rh) during two years in 15 stations in three landfills located in the hills of Reggio Emilia and to value the flows of element depositions (gram element/hectare area/year). In addition the origin of the element depositions was identified, discriminating between anthropogenic origin and soil-substrate origins. For more complete information, soils and mosses were also collected to know the level of concentration in a wide are around the landfills. The results obtained for the elements investigated using mosses and superficial soils did not amphasise any specific anomalies.JRC.H.6-Spatial data infrastructure

Adiabatic dynamics of an inhomogeneous quantum phase transition: the case of z > 1 dynamical exponent

We consider an inhomogeneous quantum phase transition across a multicritical point of the XY quantum spin chain. This is an example of a Lifshitz transition with a dynamical exponent z = 2. Just like in the case z = 1 considered in New J. Phys. 12, 055007 (2010) when a critical front propagates much faster than the maximal group velocity of quasiparticles vq, then the transition is effectively homogeneous: density of excitations obeys a generalized Kibble-Zurek mechanism and scales with the sixth root of the transition rate. However, unlike for z = 1, the inhomogeneous transition becomes adiabatic not below vq but a lower threshold velocity v', proportional to inhomogeneity of the transition, where the excitations are suppressed exponentially. Interestingly, the adiabatic threshold v' is nonzero despite vanishing minimal group velocity of low energy quasiparticles. In the adiabatic regime below v' the inhomogeneous transition can be used for efficient adiabatic quantum state preparation in a quantum simulator: the time required for the critical front to sweep across a chain of N spins adiabatically is merely linear in N, while the corresponding time for a homogeneous transition across the multicritical point scales with the sixth power of N. What is more, excitations after the adiabatic inhomogeneous transition, if any, are brushed away by the critical front to the end of the spin chain.Comment: 10 pages, 6 figures, improved version accepted in NJ

Hydrodynamics of local excitations after an interaction quench in 1D cold atomic gases

We discuss the hydrodynamic approach to the study of the time evolution -induced by a quench- of local excitations in one dimension. We focus on interaction quenches: the considered protocol consists in creating a stable localized excitation propagating through the system, and then operating a sudden change of the interaction between the particles. To highlight the effect of the quench, we take the initial excitation to be a soliton. The quench splits the excitation into two packets moving in opposite directions, whose characteristics can be expressed in a universal way. Our treatment allows to describe the internal dynamics of these two packets in terms of the different velocities of their components. We confirm our analytical predictions through numerical simulations performed with the Gross-Pitaevskii equation and with the Calogero model (as an example of long range interactions and solvable with a parabolic confinement). Through the Calogero model we also discuss the effect of an external trapping on the protocol. The hydrodynamic approach shows that there is a difference between the bulk velocities of the propagating packets and the velocities of their peaks: it is possible to discriminate the two quantities, as we show through the comparison between numerical simulations and analytical estimates. In the realizations of the discussed quench protocol in a cold atom experiment, these different velocities are accessible through different measurement procedures. ArXI

Localization and Glassy Dynamics Of Many-Body Quantum Systems

When classical systems fail to explore their entire configurational space, intriguing macroscopic phenomena like aging and glass formation may emerge. Also closed quanto-mechanical systems may stop wandering freely around the whole Hilbert space, even if they are initially prepared into a macroscopically large combination of eigenstates. Here, we report numerical evidences that the dynamics of strongly interacting lattice bosons driven sufficiently far from equilibrium can be trapped into extremely long-lived inhomogeneous metastable states. The slowing down of incoherent density excitations above a threshold energy, much reminiscent of a dynamical arrest on the verge of a glass transition, is identified as the key feature of this phenomenon. We argue that the resulting long-lived inhomogeneities are responsible for the lack of thermalization observed in large systems. Such a rich phenomenology could be experimentally uncovered upon probing the out-of-equilibrium dynamics of conveniently prepared quantum states of trapped cold atoms which we hereby suggest

ANALISIS SISTEM PENGENDALIAN INTERN PENERIMAAN DAN PENGELUARAN KAS PADA PT. ASURANSI BRINGIN SEJAHTERA ARTAMAKMUR CABANG MEDAN

Penelitian ini bertujuan untuk mengetahui sejauh mana sistem pengendalian intern penerimaan dan pengeluaran kas yang dilakukan PT. Asuransi Bringin Sejahtera Artamamakmur Cabang Medan dalam menjalankan kegiatan usahanya guna mencapai tujuan perusahaan. Teori yang digunakan dalam penelitian ini adalah teori Mulyadi. Metode yang digunakan dalam penelitian ini adalah Penelitian Kualitatif, dengan teknik analisis data Deskriptif, yaitu dengan terlebih dahulu mengumpulkan data, mengklasifikasikan serta menafsirkan data sehingga dapat memberikan gambaran yang jelas mengenai masalah yang diteliti. Dalam pengumpulan data menggunakan teknik wawancara dan dokumentasi, dimana data yang diambil merupakan data primer yang berupa bukti catatan atau laporan historis yang telah tersusun dalam arsip yang dipublikasi maupun yang tidak dipublikasikan. Hasil penelitian ini menunjukan bahwa pengendalian intern penerimaan dan pengeluaran kas PT. Asuransi Bringin Sejahtera Artamakmur Cabang Medan belum sepenuhnya memenuhi unsur-unsur pengendalian intern, karena masih adanya beberapa hal yang tidak sesuai dengan teori yang ada. Diantaranya, masih ada perangkapan tugas yang dilakukan bagian kasir dengan bagian akuntansi. Demikian juga dalam hal pembagian tugas, dimana bagian kasir diberi tanggung jawab dalam hal penagihan premi, yang sebaiknya tugas ini bukan dipegang unit tersebut. Praktik-praktik ini ditakutkan akan mengurangi keakuratan pencatatan dan juga akan membuka peluang terjadinya penyelewengan terhadap kas yang mengakibatkan kerugian perusahaan. Hal ini juga akan mengurangi keefektifan dalam praktik kerja bagian kasir, karena terlalu banyak memegang fungsi

L'Emilia nel cuore dell'Europa. Un progetto di Public History che ha viaggiato "un po' più in là dello stereotipo".

Analisi di un progetto didattico realizzato con una classe di scuola media superiore italiana in Belgio

Paesaggi transnazionali. Come approssimarsi al Belgio degli Italiani.

Il saggio descrive i processi identitari degli emigrati italiani impiegati nelle miniere nel corso del secondo dopoguerra