Equivalence of conditional and external field ensembles in absorbing state phase transitions

有向渗流中临界动力学的Lévy驱动时间淬火 disorder

Critical dynamics of the directed percolation with Lévy-driven temporally quenched disorder

本文提出了一种基于Lévy分布的时间淬火 disorder 方法，用于研究有向渗流中吸收相变的临界动力学特性，揭示了参数β对粒子密度衰减指数、总粒子数指数和扩散指数的影响。

Conditional probabilities in multiplicative noise processes

We address the calculation of transition probabilities in multiplicative noise stochastic differential equations using a path integral approach. We show the equivalence between the conditional probability and the propagator of a quantum particle with variable mass. Introducing a {\em time reparametrization}, we are able to transform the problem of multiplicative noise fluctuations into an equivalent additive one. We illustrate the method by showing the explicit analytic computation of the conditional probability of a harmonic oscillator in a nonlinear multiplicative environment.

交互量子动力学中的纠缠与吸收态转变

Entanglement and Absorbing-State Transitions in Interactive Quantum Dynamics

本研究探讨交互量子动力学中，通过测量反馈引导系统至目标状态，发现吸收态转变与纠缠转变在临界参数上不同，且引导长程关联态时两者分离明显。

Non-equilibrium absorbing state phase transitions in discrete-time quantum dynamics

We introduce a discrete-time quantum dynamics on a two-dimensional lattice that describes the evolution of a $1+1$-dimensional spin system. The underlying quantum map is constructed such that the reduced state at each time step is separable. We show that for long times this state becomes stationary and displays a continuous phase transition in the density of excited spins. This phenomenon can be understood through a connection to the so-called Domany-Kinzel automaton, which implements a classical non-equilibrium process that features a transition to an absorbing state. Near the transition dens…

Experimental signatures of an absorbing-state phase transition in an open driven many-body quantum system

Understanding and probing phase transitions in non-equilibrium systems is an ongoing challenge in physics. A particular instance are phase transitions that occur between a non-fluctuating absorbing phase, e.g., an extinct population, and one in which the relevant order parameter, such as the population density, assumes a finite value. Here we report the observation of signatures of such a non-equilibrium phase transition in an open driven quantum system. In our experiment rubidium atoms in a quasi one-dimensional cold disordered gas are laser-excited to Rydberg states under so-called facilitat…

Sampling methods for the quasistationary regime of epidemic processes on regular and complex networks

A major hurdle in the simulation of the steady state of epidemic processes is that the system will unavoidably visit an absorbing, disease-free state at sufficiently long times due to the finite size of the networks where epidemics evolves. In the present work, we compare different quasistationary (QS) simulation methods where the absorbing states are suitably handled and the thermodynamical limit of the original dynamics can be achieved. We analyze the standard QS (SQS) method, where the sampling is constrained to active configurations, the reflecting boundary condition (RBC), where the dynam…