We consider non-equilibrium time evolution after a quench of a global Hamiltonian parameter in systems described by Hamiltonians with local interactions. Within this background, we propose a protocol that allows to change global properties of the state by flipping a switch that modifies a local term of the Hamiltonian (creating a defect). A light-cone that separates two globally different regions originates from the switch. The expectation values of macroscopic observables, that is to say local observables that are spatially averaged within a subsystem, slowly approach new asymptotic values determined by the defect. The process is almost reversible: flipping again the switch produces a new light-cone with the two regions inverted. Finally, we test the protocol under repeated projective measurements. As explicit example we study the dynamics in a simple exactly solvable model but analogues descriptions apply also to generic models.
Proliferation of effective interactions: decoherence-induced equilibration in a closed many-body system
我们解决的问题是如何弱扰动，这是相当无效的小多体系统，可以导致退相干，因此不可逆性时，他们扩散的系统尺寸的增加。这个问题是固态NMR的核心。在那里，最初的局部极化由于自旋-自旋相互作用而遍布各处，该自旋-自旋相互作用保持总自旋投影，导致极化的平衡。原则上，这种量子动力学可以通过改变哈密顿量的符号来逆转。然而，反转通常被作为退相干源的不可逆相互作用扰动。局部激发恢复的分数定义的Loschillary回声（LE），在这里评估的一系列封闭的$N$自旋系统与所有的相互作用。最显着的制度的LE衰减时发生的扰动诱导增殖有效的相互作用。我们表明，如果这种扰动超过一些下限，衰变是由一个有效的费米黄金法则（FGR）。这种下限随着$ N $的增加而缩小，成为热力学极限中LE衰减的主要机制。一旦极化保持平衡的时间长于FGR时间，尽管进行了反转程序，它仍保持平衡。
Exact closed probability-free kinetic equation for system of classical particles with retarded interactions: towards microscopic foundation of kinetics
导出了考虑粒子间相互作用迟滞的经典多体系统微观分布函数的精确闭合运动方程。结果表明，相互作用的延迟导致多体系统的不可逆行为。PACS：05.20.Dd ; 05.60.- k; 45.20.- D
