The equivalence between canonical and grand canonical constraints near a random fixed point in a critical disordered system is confirmed by means of Monte Carlo simulations. The slow approach to the asymptotic distribution for canonical averaging given by the ${L}^{(\ensuremath{\alpha}/\ensuremath{\nu}{)}_{\mathrm{random}}}$ term is overcome by simulating long range correlated diluted Ising systems with $(\ensuremath{\alpha}/\ensuremath{\nu}{)}_{\mathrm{random}}=(a\ensuremath{-}d)$ for the particular values
a=2 (linear defects) and
d=3 (three dimensional systems).
Simulating Markovian open quantum systems in the semiclassical regime poses a grand challenge for computational physics, as the highly oscillatory nature of the dynamics imposes prohibitive resolution requirements on traditional grid-based methods. To overcome this barrier, this paper introduces an efficient Frozen Gaussian Sampling (FGS) algorithm based on the Wigner-Fokker-Planck phase-space formulation. The proposed algorithm exhibits two transformative advantages. First, for the computation of physical observables, its sampling error is independent of the semiclassical parameter
ε, thus fundamentally breaking the prohibitive computational scaling faced by grid methods in the semiclassical limit. Second, its mesh-free nature entirely eliminates the boundary-induced instabilities that constrain long-time grid-based simulations. Leveraging these capabilities, the FGS algorithm serves as a powerful investigatory tool for exploring the long-time behavior of open quantum systems. Specifically, we provide compelling numerical evidence for the existence of steady states in strongly non-harmonic potentials-a regime where rigorous analytical results are currently lacking.
Simulation is a ubiquitous tool for understanding and predicting the behavior of complex systems, ranging from those in natural sciences to those in social studies. When it comes to quantum systems, however, conventional simulation methods encounter fundamental limitations imposed by quantum physics. To overcome this challenge, the concept of using quantum systems to simulate other quantum systems, namely, quantum simulation, has emerged as an indispensable paradigm. In this special issue, we explore the underlying concepts and theoretical frameworks that drive this rapidly developing field.