# gst: experimental observation of hidden multistability in nonlinear systems.

<< ️Multistability, the coexistence of multiple stable states, is a cornerstone of nonlinear dynamical systems, governing their equilibrium, tunability, and emergent complexity. Recently, the concept of hidden multistability, where certain stable states evade detection via conventional continuous parameter sweeping, has garnered increasing attention due to its elusive nature and promising applications.  >>

<< ️In this Letter, (AA) present the first experimental observation of hidden multistability using a programmable acoustic coupled-cavity platform that integrates competing self-focusing and self-defocusing Kerr nonlinearities. Beyond established bistability, (They) demonstrate semi- and fully-hidden tristabilities by precisely programming system parameters. Crucially, the hidden stable states, typically inaccessible via the traditional protocol, are unambiguously revealed and dynamically controlled through pulsed excitation, enabling flexible transitions between distinct types of stable states. >>

Kun Zhang, Qicheng Zhang, Shuaishuai Tong, et al. Experimental Observation of Hidden Multistability in Nonlinear Systems. arXiv: 2511.04150v1 [nlin.CD]. Nov 6, 2025.

https://arxiv.org/abs/2511.04150

Also: instability, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, stability, multistability, hidden multistability, semi- fully-hidden tristabilities, pulsed excitation.

# gst: energy transport and chaos in a one-dimensional disordered nonlinear stub lattice

<< ️(AA) investigate energy propagation in a one-dimensional stub lattice in the presence of both disorder and nonlinearity. In the periodic case, the stub lattice hosts two dispersive bands separated by a flat band; however, (They) show that sufficiently strong disorder fills all intermediate band gaps. By mapping the two-dimensional parameter space of disorder and nonlinearity, (AA) identify three distinct dynamical regimes (weak chaos, strong chaos, and self-trapping) through numerical simulations of initially localized wave packets. >>

<< ️When disorder is strong enough to close the frequency gaps, the results closely resemble those obtained in the one-dimensional disordered discrete nonlinear Schrödinger equation and Klein-Gordon lattice model. In particular, subdiffusive spreading is observed in both the weak and strong chaos regimes, with the second moment m_2 of the norm distribution scaling as m_2 ∝ t^0.33 and m_2 ∝ t^0.5, respectively. The system’s chaotic behavior follows a similar trend, with the finite-time maximum Lyapunov exponent Λ decaying as Λ ∝ t^−0.25 and Λ ∝ t^−0.3. For moderate disorder strengths, i.e., near the point of gap closing, (They) find that the presence of small frequency gaps does not exert any noticeable influence on the spreading behavior. >>

<< ️(AA) findings extend the characterization of nonlinear disordered lattices in both weak and strong chaos regimes to other network geometries, such as the stub lattice, which serves as a representative flat-band system. >>

Su Ho Cheong, Arnold Ngapasare, et al. Energy transport and chaos in a one-dimensional disordered nonlinear stub lattice. arXiv: 2511.04159v1 [nlin.CD].  Nov 6, 2025.

https://arxiv.org/abs/2511.04159

Also: network, waves, disorder, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, networks, waves, disorder, chaos, stub lattice, subdiffusive spreading.

# gst: dynamical phase transitions across slow and fast regimes in a two-tone driven Duffing resonator

<< In this work, (AA) established an analytical framework to describe dynamical phase transitions in a Duffing resonator under bichromatic driving. (They) reveal two regimes: a slow-beating one, where the secondary tone slowly modulates the main drive and can push the system past bifurcations, and a fast-modulation one. >>

<< (AA) analysis shows that even a weak secondary tone can profoundly reshape the dynamics, inducing transitions between coexisting attractors that cannot be explained by perturbative treatments of the secondary tone. >>

<< This provides a qualitative yet predictive tool to detect and categorize different types of dynamical phase transitions in two-tone driven nonlinear systems. >>

Soumya S. Kumar, Javier del Pino, et al. Dynamical Phase Transitions Across Slow and Fast Regimes in a Two-Tone Driven Duffing Resonator. arXiv: 2511.01985v1 [cond-mat.mes-hall]. Nov 3, 2025.

https://arxiv.org/abs/2511.01985

 

Also: attractor, transition, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, attractor, transitions, chaos,  Duffing resonator, bichromatic driving. 

# gst: apropos of shape transitions, midveins regulate the shape formation of drying leaves.

<< ️Dried leaves in nature often exhibit curled and crumpled morphologies, typically attributed to internal strain gradients that produce dome-like shapes. However, the origin of these strain gradients remains poorly understood. Although leaf veins--particularly the midvein--have been suggested to influence shape formation, their mechanical role has not been systematically investigated. >>

<< ️Here, (AA) demonstrate that mechanical constraints imposed by the midvein play a crucial role in generating the diverse morphologies that emerge during leaf drying. Combining numerical simulations and theoretical analysis, (They) show that a uniformly shrinking leaf lamina constrained by a non-shrinking midvein gives rise to two distinct types of configurations: curling-dominated and folding-dominated morphologies. In the curling-dominated regime, both S-curled and C-curled shapes emerge, with C-curled configurations more commonly observed due to their lower elastic energy. In contrast, the folding-dominated regime features folding accompanied by edge waviness. Theoretical modeling reveals a linear relationship between midvein curvature and mismatch strain, consistent with simulation results. >>

<< ️Moreover, (AA) find that the morphological outcome is governed by the ratio of bending stiffnesses between the lamina and the midvein. (They) construct a comprehensive phase diagram for the transitions between different configurations. These findings provide a mechanical framework for understanding shape formation in drying leaves, offering new insights into natural morphing processes and informing the design of bio-inspired morphable structures. >>

Kexin Guo, Yafei Zhang, et al. Midveins regulate the shape formation of drying leaves. arXiv: 2507.01813v1 [cond-mat.soft]. Jul 2, 2025.

https://arxiv.org/abs/2507.01813

Also: waves, transition,  in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, transition, leaf drying, curled and crumpled morphologies, internal strain gradients, dome-like shapes, curling-dominated and folding-dominated morphologies, edge waviness, midvein curvature and mismatch strain, life.

# life: apropos of immigration problems, 'China is going to win the AI race', by Jensen.

<< ️"As I have long said, China is nanoseconds behind America in AI," Nvidia CEO Jensen Huang said in a statement posted on X late on Wednesday. >>

<< ️"A policy that causes America to lose half of the world's AI developers is not beneficial in the long term, it hurts us more," >>

Nvidia's Jensen Huang: 'China is going to win the AI race,' FT reports. Reuters. Nov 6, 2025.

https://www.reuters.com/world/asia-pacific/nvidias-jensen-huang-says-china-will-win-ai-race-with-us-ft-reports-2025-11-05/  Nvidia’s Jensen Huang says China ‘will win’ AI race with US.  https://www.ft.com/content/53295276-ba8d-4ec2-b0de-081e73b3ba43 

Also: life, ai (artificial intell) (bot), in https://www.inkgmr.net/kwrds.html 

Keywords: life, aibot, artificial intelligence.

# gst: a probability space at inception of stochastic process.

<< ️Recently, progress has been made in the theory of turbulence, which provides a framework on how a deterministic process changes to a stochastic one owing to the change in thermodynamic states. It is well known that, in the framework of Newtonian mechanics, motions are dissipative; however, when subjected to periodic motion, a system can produce nondissipative motions intermittently and subject to resonance. It is in resonance that turbulence occurs in fluid flow, solid vibration, thermal transport, etc. In this, the findings from these physical systems are analyzed in the framework of statistics with their own probability space to establish their compliance to the stochastic process. >>

<< ️In particular, a systematic alignment of the inception of the stochastic process with the signed measure theory, signed probability space, and stochastic process was investigated. It was found that the oscillatory load from the dissipative state excited the system and resulted in a quasi-periodic probability density function with the negative probability regimes. In addition, the vectorial nature of the random velocity splits the probability density function along both the positive and negative axes with slight asymmetricity. By assuming that a deterministic process has a probability of 1, (AA) can express the inception of a stochastic process, and the subsequent benefit is that a dynamic fractal falls on the probability density function. Moreover, (They) leave some questions of inconsistency between the physical system and the measurement theory for future investigation. >>

Liteng Yang, Yuliang Liu, et al. A Probability Space at Inception of Stochastic Process. arXiv: 2510.20824v1 [nlin.CD]. Oct 8, 2025.

https://arxiv.org/abs/2510.20824

Also: turbulence, dissipation, intermittency, random, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, turbulence, dissipation, intermittency, randomness, transitions.

# gst: long-range resonances in quasiperiodic many-body localization.

<< ️(AA) investigate long-range resonances in quasiperiodic many-body localized (MBL) systems. (..) Contrary to the expectation that the ergodic-MBL transition in quasiperiodic systems should be sharper due to the absence of Griffiths regions, (They) uncover a broad unconventional regime at strong quasiperiodic potential, characterized by fat-tailed distributions of longitudinal correlations at long distance. This reveals the presence of atypical eigenstates with strong long-range correlations in a regime where standard diagnostics indicate stable MBL. >>

<< ️(AA) further identify these anomalous eigenstates as quasi-degenerate pairs of resonant cat states, which exhibit entanglement at long distance. These findings advance the understanding of quasiperiodic MBL and identify density-correlation measurements in ultracold atomic systems as a probe of long-range resonances. >>

Ashirbad Padhan, Jeanne Colbois, et al. Long-range resonances in quasiperiodic many-body localization. arXiv: 2510.24704v1 [cond-mat.dis-nn]. Oct 28, 2025.

https://arxiv.org/abs/2510.24704

Also: order, disorder, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, order, disorder, transitions, interplay between disorder and interactions, long-range resonances, strong long-range correlations, many-body localization (MBL), entanglement at long distance, atypical eigenstates.