Influence of classical resonances on chaotic tunnelling

Dynamical tunnelling between symmetry-related stable modes is studied in the periodically driven pendulum. We present strong evidence that the tunnelling process is governed by nonlinear resonances that manifest within the regular phase-space islands on which the stable modes are localized. By means of a quantitative numerical study of the corresponding Floquet problem, we identify the trace of such resonances not only in the level splittings between near-degenerate quantum states, where they lead to prominent plateau structures, but also in overlap matrix elements of the Floquet eigenstates, which reveal characteristic sequences of avoided crossings in the Floquet spectrum. The semiclassical theory of resonance-assisted tunnelling yields good overall agreement with the quantum-tunnelling rates, and indicates that partial barriers within the chaos might play a prominent role

Becoming classical: A possible influence on the quantum-to-classical transition

Although cosmic expansion at very small distances is usually dismissed as entirely inconsequential, it appears that these extraordinarily small effects may in fact have a real and significant influence on our world. Calculations suggest that the minute recessional velocities associated with regions encompassed by extended bodies may have a role in creating the distinction between quantum and classical behavior. Using an uncertainty in position estimated from the spread in velocities associated with its size, the criterion that the uncertainty in position should be smaller than the extension of the object leads to a threshold size that could provide a fundamental limit distinguishing the realm of objects governed by classical laws from those governed by quantum mechanics.Comment: 2 pages, 0 figures, submitted to Nature for publication as a brief communicatio

Influence of lattice distortions in classical spin systems

We investigate a simple model of a frustrated classical spin chain coupled to adiabatic phonons under an external magnetic field. A thorough study of the magnetization properties is carried out both numerically and analytically. We show that already a moderate coupling with the lattice can stabilize a plateau at 1/3 of the saturation and discuss the deformation of the underlying lattice in this phase. We also study the transition to saturation where either a first or second order transition can occur, depending on the couplings strength.Comment: Submitted to Phys. Rev.

“Above all Greek, above all Roman Fame”: Classical Rhetoric in America during the Colonial and Early National Periods

The broad and profound influence of classical rhetoric in early America can be observed in both the academic study of that ancient discipline, and in the practical approaches to persuasion adopted by orators and writers in the colonial period, and during the early republic. Classical theoretical treatises on rhetoric enjoyed wide authority both in college curricula and in popular treatments of the art. Classical orators were imitated as models of republican virtue and oratorical style. Indeed, virtually every dimension of the political life of early Ameria bears the imprint of a classical conception of public discourse. This essay marks the various specific aspects of the reception and influence of the classical rhetorical tradition in the learning, speaking and writing of Americans in the eighteenth and early nineteenth centuries

The Influence of Classical Music Therapy at Physiological Response to Patients Who Have Orthopedics Praoperatif Anxiety

Persiapan mental pasien sebelum dilakukan operasi sangat diperlukan. Apabila pasien mengalami kecemasan berat dan panik rencana operasi akan tertunda, hal tersebut memungkinkan resiko infeksi akan lebih besar. Dari berbagai penelitian menunjukan bahwa musik memiliki pengaruh yang kuat terhadap kesehatan, terutama dalam menenangkan pikiran, menurunkan ketegangan fisik dan menciptakan keadaan rileks, apabila pasien dalam keadaan rileks diharapkan dapat mempengaruhi respon fisiologis. Tujuan penelitian ini adalah untuk mengetahui pengaruh terapi musik klasik terhadap respon fisiologis pada pasien yang mengalami kecemasan praoperatif ortopedi. Desain penelitian adalah pra-eksperiment dengan jumlah sampel 30 orang menggunakan purposive sampling. Terapi musik diberikan selama ±30 menit. Analisis yang digunakan adalah Paired Sample T Test dan Wilcoxon. Didapatkan mean tekanan darah sistol sebelum terapi adalah 120,2 mmHg, setelah terapi 119,6 mmHg, p value= 0,227. Mean tekanan darah diastol sebelum terapi adalah 74,1 mmHg, setelah  terapi adalah 73,2 mmHg, p value= 0,133. Mean frekuensi denyut jantung sebelum terapi adalah 81,8 x/menit, setelah terapi adalah 79 x/menit, p value= 0,005. Median frekuensi pernafasan sebelum terapi adalah 23 x/menit, setelah dilakukan terapi adalah 21 x/menit, nilai p value = 0,001. Hal ini menunjukkan terapi musik klasik memiliki pengaruh terhadap frekuensi denyut jantung dan frekuensi pernafasan pada pasien yang mengalami kecemasan praoperatif ortopedi.  Peneliti menyarankan pemberian terapi musik klasik dengan frekuensi 2 sampai 3 kali sehari sebelum pasien menjalani operasi agar mendapatkan efek relaksasi yang optimal

Influence of Generic Scale Invariance on Classical and Quantum Phase Transitions

This review discusses a paradigm that has become of increasing importance in the theory of quantum phase transitions; namely, the coupling of the order-parameter fluctuations to other soft modes, and the resulting impossibility of constructing a simple Landau-Ginzburg-Wilson theory in terms of the order parameter only. The soft modes in question are manifestations of generic scale invariance, i.e., the appearance of long-range order in whole regions in the phase diagram. The concept of generic scale invariance, and its influence on critical behavior, is explained using various examples, both classical and quantum mechanical. The peculiarities of quantum phase transitions are discussed, with emphasis on the fact that they are more susceptible to the effects of generic scale invariance than their classical counterparts. Explicit examples include: the quantum ferromagnetic transition in metals, with or without quenched disorder; the metal-superconductor transition at zero temperature; and the quantum antiferromagnetic transition. Analogies with classical phase transitions in liquid crystals and classical fluids are pointed out, and a unifying conceptual framework is developed for all transitions that are influenced by generic scale invariance.Comment: 55pp, 25 eps figs; final version, to appear in Rev Mod Phy

Classical Motion in Random Potentials

We consider the motion of a classical particle under the influence of a random potential on R^d, in particular the distribution of asymptotic velocities and the question of ergodicity of time evolution.Comment: 45 pages, 3 figure

Nonadiabatic Dynamics in Open Quantum-Classical Systems: Forward-Backward Trajectory Solution

A new approximate solution to the quantum-classical Liouville equation is derived starting from the formal solution of this equation in forward-backward form. The time evolution of a mixed quantum-classical system described by this equation is obtained in a coherent state basis using the mapping representation, which expresses $N$ quantum degrees of freedom in a 2N-dimensional phase space. The solution yields a simple non-Hamiltonian dynamics in which a set of $N$ coherent state coordinates evolve in forward and backward trajectories while the bath coordinates evolve under the influence of the mean potential that depends on these forward and backward trajectories. It is shown that the solution satisfies the differential form of the quantum-classical Liouville equation exactly. Relations to other mixed quantum-classical and semi-classical schemes are discussed.Comment: 28 pages, 1 figur