Nonstationary longtime dynamics was recently observed in a driven two-component Bose-Einstein condensate coupled to an optical cavity [N. Dogra, M. Landini, K. Kroeger, L. Hruby, T. Donner, and T. Esslinger, arXiv:1901.05974] and analyzed in mean-field theory. We solve the underlying model in the thermodynamic limit and show that this system is always dynamically unstable-even when mean-field theory predicts stability. Instabilities always occur in higher-order correlation functions leading to squeezing and entanglement induced by cavity dissipation. The dynamics may be understood as the formation of a dissipative time crystal. We use perturbation theory for finite system sizes to confirm the nonstationary behavior.
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http://dx.doi.org/10.1103/PhysRevLett.123.260401 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
The question of what mechanisms maintain tropical biodiversity is a critical frontier in ecology, intensified by the heightened risk of biodiversity loss faced in tropical regions. Ecological theory has shed light on multiple mechanisms that could lead to the high levels of biodiversity in tropical forests. But variation in species abundances over time may be just as important as overall biodiversity, with a more immediate connection to the risk of extirpation and biodiversity loss.
View Article and Find Full Text PDFRisk Anal
January 2025
Department of Industrial Engineering, School of Mechanical Engineering, Northwestern Polytechnical University, Xi'an, China.
Vaccination is the most effective method of preventing and controlling the transmission of infectious diseases within populations. However, the phenomenon of waning immunity can induce periodic fluctuations in epidemic spreading. This study proposes a coupled epidemic-vaccination dynamic model to analyze the influence of immunity waning on the epidemic spreading within the context of voluntary vaccination.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
CONICET-UNR, Laboratorio de Materiales (LEIM), Escuela de Ingeniería Eléctrica, Centro de Tecnología e Investigación Eléctrica (CETIE), Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Avda. Pellegrini 250, 2000 Rosario, Argentina.
The influence on the mobility of polypeptide chains caused by strain misfit due to molecular electric dipole distortions under applied electric fields up to 769 kV m, in cow cortical femur samples annealed at 373 K, 423 K, and 530 K, is determined. The behaviour of strain misfit as a function of the electric field strength is determined from a mean-field model based on the Eshelby theory. In addition, Friedel's model for describing the mobility of dislocations in continuum media has been modified to determine the interaction energy between electrically generated obstacles and the polypeptide chains.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Institute for Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
We investigate the orientational properties of a homogeneous and inhomogeneous tetrahedral four-patch fluid (Bol-Kern-Frenkel model). Using integral equations, either (i) HNC or (ii) a modified HNC scheme with a simulation input, the full orientational dependence of pair and direct correlation functions is determined. Density functionals for the inhomogeneous problem are constructed via two different methods.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Physics and Astronomy, University of Manitoba, Winnipeg R3T 2N2, Canada.
Theory and simulations are used to demonstrate implementation of a variational Bayes algorithm called "active inference" in interacting arrays of nanomagnetic elements. The algorithm requires stochastic elements, and a simplified model based on a magnetic artificial spin ice geometry is used to illustrate how nanomagnets can generate the required random dynamics. Examples of tracking and PID control are demonstrated and shown to be consistent with the original stochastic differential equation formulation of active inference.
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