Meibohm Jan, Esposito Massimiliano
Complex Systems and Statistical Mechanics, Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg, Luxembourg.
Phys Rev Lett. 2022 Mar 18;128(11):110603. doi: 10.1103/PhysRevLett.128.110603.
We uncover a finite-time dynamical phase transition in the thermal relaxation of a mean-field magnetic model. The phase transition manifests itself as a cusp singularity in the probability distribution of the magnetization that forms at a critical time. The transition is due to a sudden switch in the dynamics, characterized by a dynamical order parameter. We derive a dynamical Landau theory for the transition that applies to a range of systems with scalar, parity-invariant order parameters. Close to criticalilty, our theory reveals an exact mapping between the dynamical and equilibrium phase transitions of the magnetic model, and implies critical exponents of mean-field type. We argue that interactions between nearby saddle points, neglected at the mean-field level, may lead to critical, spatiotemporal fluctuations of the order parameter, and thus give rise to novel, dynamical critical phenomena.
我们在平均场磁模型的热弛豫中发现了一种有限时间动力学相变。该相变在临界时刻形成的磁化强度概率分布中表现为尖点奇异性。这种转变是由于动力学的突然转变，其特征由一个动力学序参量来描述。我们推导了适用于一系列具有标量、宇称不变序参量系统的该转变的动力学朗道理论。接近临界点时，我们的理论揭示了磁模型动力学相变与平衡相变之间的精确映射关系，并暗示了平均场类型的临界指数。我们认为，在平均场水平上被忽略的附近鞍点之间的相互作用，可能导致序参量的临界时空涨落，从而产生新的动力学临界现象。
