Local Markovian noise cannot bring entanglement back, but it can bring magic back. Unlike separability, stabilizer membership is not preserved by local channels, allowing dissipation to push states out of the stabilizer polytope as well as in. Under local amplitude damping, the $n$-qubit GHZ family $α|0^n\rangle+β|1^n\rangle$ ($0<α<β$) loses its magic at a lower damping strength $γ_-$ and regains it at a higher one $γ_+$, while entanglement is irreversibly lost at $γ_e$. This magic--entanglement complementarity, $γ_e+γ_+=1$ for every $n$, reflects a system--environment duality of amplitude damping. Within real phase-covariant Markovian semigroups the phenomenon is mapped out in full: zero-temperature rebirth occurs if and only if $T_2>T_1$, unital dynamics produce no rebirth, and sufficiently weak thermal excitation confines rebirth to a finite magic island ending in a second sudden death. For small $α$, the reborn magic resides in a fully separable state with all proper marginals stabilizer, yet parity-syndrome extraction concentrates it onto a single qubit for magic-state distillation, without loss of expected robustness and with optimal per-register yield $α^2/2$. Local
We prove generalizations of the first and second Ray-Knight theorems, for a large class of non-symmetric strong Markov processes. These results link the local times of the Markov process with the squares of associated Gaussian processes. This connection allows us to establish results about the exact modulus of continuity (in the spatial variable) of the local times. Our approach is different from earlier treatments which were based on associated permanental processes rather than Gaussian processes. The type of process with which we work can be described as follows. Start with a symmetric Markov process with finite lifetime; upon its death resurrect it at a place in the state space chosen at random, independent of the past. Continue in this way, resurrecting at each death, to obtain a recurrent process. The rebirthing procedure destroys the symmetry of the original process, leading to a large class of non-symmetric processes. The main results are illustrated by many examples.
Let $S$ a be locally compact space with a countable base. Let $\cal Y$ be a transient symmetric Borel right process with state space $S$ and continuous strictly positive $p$--potential densities $u^p(x,y)$. Local and uniform moduli of continuity are obtained for the local times of both fully and partially rebirthed versions of $\cal Y$. A fully rebirthed version of $\cal Y$ is an extension of $\cal Y$ so that instead of terminating at the end of its lifetime it is immediately ``reborn'' with a probability measure $μ$, on $S$. I.e., the process goes to the set $B\subset S$ with probability $μ(B) $, after which it continues to evolve the way $\YY$ did, being reborn with probability $μ$ each time it dies. This rebirthed version of $\cal Y$ is a recurrent Borel right process with state space $S$ and $p$-potential densities of form, \[ u^p(x,y)+h(x,y),\qquad x,y\in S,\,\, p>0, \] where $h(x,y)$ is not symmetric. The local times of the rebirthed process are given in terms of the local times of $\cal Y$ and isomorphism theorems in the spirit of Dynkin, Eisenbam and Kaspi are obtained that relate these local times to generalized chi--square processes formed by Gaussian processes with co
Model inversion is a widely adopted technique in data-free learning that reconstructs synthetic inputs from a pretrained model through iterative optimization, without access to original training data. Unfortunately, its application to state-of-the-art Vision Transformers (ViTs) poses a major computational challenge, due to their expensive self-attention mechanisms. To address this, Sparse Model Inversion (SMI) was proposed to improve efficiency by pruning and discarding seemingly unimportant patches, which were even claimed to be obstacles to knowledge transfer. However, our empirical findings suggest the opposite: even randomly selected patches can eventually acquire transferable knowledge through continued inversion. This reveals that discarding any prematurely inverted patches is inefficient, as it suppresses the extraction of class-agnostic features essential for knowledge transfer, along with class-specific features. In this paper, we propose Patch Rebirth Inversion (PRI), a novel approach that incrementally detaches the most important patches during the inversion process to construct sparse synthetic images, while allowing the remaining patches to continue evolving for future
Hawrami, a dialect of Kurdish, is classified as an endangered language as it suffers from the scarcity of data and the gradual loss of its speakers. Natural Language Processing projects can be used to partially compensate for data availability for endangered languages/dialects through a variety of approaches, such as machine translation, language model building, and corpora development. Similarly, NLP projects such as text classification are in language documentation. Several text classification studies have been conducted for Kurdish, but they were mainly dedicated to two particular dialects: Sorani (Central Kurdish) and Kurmanji (Northern Kurdish). In this paper, we introduce various text classification models using a dataset of 6,854 articles in Hawrami labeled into 15 categories by two native speakers. We use K-nearest Neighbor (KNN), Linear Support Vector Machine (Linear SVM), Logistic Regression (LR), and Decision Tree (DT) to evaluate how well those methods perform the classification task. The results indicate that the Linear SVM achieves a 96% of accuracy and outperforms the other approaches.
The LK-99 hype came and went but the great potential of the apatite class of materials as platform for flat bands research must not be swept away in the process. A heuristic reinterpretation of the atomic structure of LK-99 is offered, including electronic signatures from the fully oxidized to the fully reduced. Here, copper is proposed to reside in the apatite channel rather than doping the Lead sublattice. Contact is made with the experimental x-ray powder diffractogram. The electronic signatures are found to reflect those of local [O-Cu-O] and [O-Cu-Vo**] molecular ions, where Vo** is a 2+ charged vacant oxygen site in the apatite channel. The local nature warrants flat bands. Charge carrier concentration is controlled by the oxygen content. Fully reduced LK-99 is a wide band gap insulator with a well-developed intermediate band. Fully oxidized LK-99 is a magnetic insulator, while the partially reduced LK-99 allows for hopping of holes between anti bonding pi orbitals of non-magnetic and magnetic [O-Cu-O] moieties. The findings are extended to include the case where half of the Cu atoms are replaced by Ni and half by Zn. For [O-Ni-O] +[O-Zn-Vo**] inter-site accidental near degen
In this paper, we clarify the mechanisms underlying a general phenomenon present in pulse-coupled heterogeneous inhibitory networks: inhibition can induce not only suppression of the neural activity, as expected, but it can also promote neural reactivation. In particular, for globally coupled systems, the number of firing neurons monotonically reduces upon increasing the strength of inhibition (neurons' death). However, the random pruning of the connections is able to reverse the action of inhibition, i.e. in a sparse network a sufficiently strong synaptic strength can surprisingly promote, rather than depress, the activity of the neurons (neurons' rebirth). Thus the number of firing neurons reveals a minimum at some intermediate synaptic strength. We show that this minimum signals a transition from a regime dominated by the neurons with higher firing activity to a phase where all neurons are effectively sub-threshold and their irregular firing is driven by current fluctuations. We explain the origin of the transition by deriving an analytic mean field formulation of the problem able to provide the fraction of active neurons as well as the first two moments of their firing statisti
We present a detailed study of the entanglement dynamics of a two-qubit system coupled to independent non-Markovian environments, employing hierarchy equations. This recently developed theoretical treatment can conveniently solve non-Markovian problems and take into consideration the correlation between the system and bath in an initial state. We concentrate on calculating the death and rebirth time points of the entanglement to obtain a general view of the concurrence curve and explore the behavior of entanglement dynamics with respect to the coupling strength, the characteristic frequency of the noise bath and the environment temperature.
We study the nonlinear stage of preheating in a model consisting of a single inflaton field $φ$ nonminimally coupled to the spacetime curvature and considering a self-coupling quartic potential V ($φ$) = $λφ^4/4$. As the first motivation, we mention that this nonminimally coupled model agrees with the observational data. The second and the central issue of the present work is to exhibit aspects of wave turbulence associated with the mechanism of energy transfer from the inflaton field to the inhomogeneous fluctuations towards a state of thermalization. The imprints of the turbulence phase are mainly shown in the power spectra in time and wavenumber of relevant quantities such as the variance and the energy density of the inflaton field. We performed the simulations for several values of the nonminimally coupled models and taking into account the backreaction of the inflaton fluctuations in the dynamics of the Universe, and that allowed to determine the effective equation of state.
We report the prediction of metallic quasione-dimensional $sp^{3}$-hybridized silicon allotropes in the form of prismanes. Silicon prismanes or polysilaprismanes are the silicon nanotubes of a special type constructed from the dehydrogenated molecules of cyclosilanes (silicon rings). By means of density functional theory the electronic, geometry, energy, and some mechanical properties of these tubes were investigated. Our results show that silicon polyprismanes are thermodynamically stable compounds, and the character of the energy spectrum, as well as the behavior of transmission function near the Fermi level, show that they exhibit non-typical for the silicon systems metallic nature. Moreover, the metallic state of polysilaprismanes is resistant to the mechanical stresses applied along their main axis. Unusual properties predicted in the presented study discover new prospects of application of silicon nanostructures as the basic elements of future micro- and nanoelectronics, as well as in energy, metrology, medical, and information technologies.
Quantum entanglement, the essential resource for quantum information processing, has rich dynamics under different environments. Probing different entanglement dynamics typically requires exquisite control of complicated system-environment coupling in real experimental systems. Here, by a simple control of the effective solid-state spin bath in a diamond sample, we observe rich entanglement dynamics, including the conventional asymptotic decay as well as the entanglement sudden death, a term coined for the phenomenon of complete disappearance of entanglement after a short finite time interval. Furthermore, we observe counter-intuitive entanglement rebirth after its sudden death in the same diamond sample by tuning an experimental parameter, demonstrating that we can conveniently control the non-Markovianity of the system-environment coupling through a natural experimental knob. Further tuning of this experimental knob can make the entanglement dynamics completely coherent under the same environmental coupling. Probing of entanglement dynamics, apart from its fundamental interest, may find applications in quantum information processing through control of the environmental coupling.
The planetary nebula (PN) A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using HST images we have detected the angular expansion of these knots and derived an age of 850+280-150 yr. To investigate the spectral and spatial properties of the soft X-ray emission detected by ROSAT, we have obtained Chandra and XMM-Newton observations of A30. The X-ray emission from A30 can be separated into two components: a point-source at the central star and diffuse emission associated with the hydrogen-poor knots and the cloverleaf structure inside the nebular shell. To help us assess the role of the current stellar wind in powering this X-ray emission, we have determined the stellar parameters of the central star of A 30 using a non-LTE model fit to its optical and UV spectrum. The spatial distribution and spectral properties of the diffuse X-ray emission is suggestive that it is generated by the post-born-again and present fast stellar winds interacting with the hydrogen-poor ejecta of the born-again event. This emission can be attributed to shock-heated plasma, as the hydrogen-poor knots are ablated by the stellar winds,
The entangled behavior of different dimensional systems driven by classical external random field is investigated. The amount of the survival entanglement between the components of each system is quantified. There are different behaviors of entanglement that come into view decay, sudden death, sudden birth and long-lived entanglement. The maximum entangled states which can be generated from any of theses suggested systems are much fragile than the partially entangled ones. The systems of larger dimensions are more robust than those of smaller dimensions systems, where the entanglement decay smoothly, gradually and may vanish for a very short time. For the class of $2\times 3$ dimensional system, the one parameter family is found to be more robust than the two parameters family. Although the entanglement of driven $ 2 \times 3$ dimensional system is very sensitive to the classical external random field, one can use them to generate a long-lived entanglement.
The purpose of this note is to show that W3 algebras originate from an unusual interplay between the breakings of the reparametrization invariance under the diffemorphism action on the cotangent bundle of a Riemann surface. It is recalled how a set of smooth changes of local complex coordinates on the base space are collectively related to a background within a symplectic framework. The power of the method allows to calculate explicitly some primary fields whose OPEs generate the algebra as explicit functions in the coordinates: this is achieved only if well defined conditions are satisfied, and new symmetries emerge from the construction. Moreoverer, when primary flelds are introduced outside of a coordinate description the W3 symmetry byproducts acquire a good geometrical definition with respect to holomorphic changes of charts.
This is the translation into English of my paper published in Russian at the paper collection on cosmology at \\ 1981. The content of the book is presented in the Appendix. This is the first paper where the dynamical mechanism of phoenix universe was worked out. The notion of phoenix universe was first mentioned in the paper by Lemaitre in 1933, where he assumed that a repetition of successive phases of expansion and contraction was possible. Lemaitre called such model of the universe, that is born, dies and is reborn, the phoenix model, named after the mythical bird able to reborn from the ashes. According to the author, there could be an infinite number of such cycles in the past and future. In this model, however, a possible solution to the fundamental question was unclear, what was the mechanism for the rebirth of the universe. This mechanism was worked out in my paper, published in 1980 in Russian. Moreover, in our recent paper with E. Arbuzova a mechanism of dynamical cancellation of vacuum energy was proposed, that permits to eliminate vacuum energy locally down to zero and permits universe to jump to a lower hot level, leading to rebirth of a hot universe.
Scaling robot learning requires large-scale, diverse demonstrations, yet real-world data collection via teleoperation remains prohibitively expensive and time-consuming. While video diffusion models offer a promising avenue for data scaling, existing generative approaches are often limited to superficial visual augmentation, or suffer from embodiment hallucinations that yield physically infeasible motions. We present a generalizable embodiment-centric world model that achieves scalable data generation by synthesizing photorealistic demonstrations with novel objects, in novel scenes, and from novel viewpoints. Our approach anchors generation to rendered robot motion while conditioning on explicit scene and object priors, effectively decoupling trajectory execution from environment synthesis. This formulation has the potential to unlock two powerful data scaling capabilities: (1) retrieval and rebirth, which repurposes existing trajectories into entirely new contexts without new motion data; and (2) prop-free teleoperation, where operators manipulate empty air and the model hallucinates the target objects and scene afterwards, eliminating reset time. We demonstrate with real-world ex
Continual learning--the ability to acquire, retain, and refine knowledge over time--has always been fundamental to intelligence, both human and artificial. Historically, different AI paradigms have acknowledged this need, albeit with varying priorities: early expert and production systems focused on incremental knowledge consolidation, while reinforcement learning emphasised dynamic adaptation. With the rise of deep learning, deep continual learning has primarily focused on learning robust and reusable representations over time to solve sequences of increasingly complex tasks. However, the emergence of Large Language Models (LLMs) and foundation models has raised the question: Do we still need continual learning when centralised, monolithic models can tackle diverse tasks with access to internet-scale knowledge? We argue that continual learning remains essential for three key reasons: (i) continual pre-training is still necessary to ensure foundation models remain up to date, mitigating knowledge staleness and distribution shifts while integrating new information; (ii) continual fine-tuning enables models to specialise and personalise, adapting to domain-specific tasks, user prefer
The spherically bent crystal analyzer (SBCA) is a widely-adopted hard x-ray optic, renowned for its good energy resolution and large collection solid angle. It is frequently employed in synchrotron-based techniques like Resonant Inelastic X-ray Scattering (RIXS) and X-ray Emission Spectroscopy, as well as in the rebirth of laboratory-based X-ray Absorption Fine Strucure (XAFS) and XES, and its predominant use has been in 'symmetric' operation on the Rowland circle. The recent study of Gironda et al. (J. Anal. At. Spectrom., 2024, 39, 1375) emphasizes the benefits of 'asymmetric' SBCA operation, demonstrating the use of multiple crystal reflections from a single SBCA to broaden its accessible energy range. Furthermore, Gironda et al. demonstrate that asymmetric operation frequently mitigates energy broadening intrinsic to Johann optics and propose that under a specific Rowland circle configuration, designated here the Johann Normal Alignment (JNA), such broadening is eradicated altogether. We report extensive ray tracing simulations to scrutinize the impact of asymmetric configurations on energy broadening and detector plane defocusing. We find that the performance of asymmetric SBC
Videos contain a wealth of information, and generating detailed and accurate descriptions in natural language is a key aspect of video understanding. In this paper, we present video-SALMONN 2, an advanced audio-visual large language model (LLM) with low-rank adaptation (LoRA) designed for enhanced video (with paired audio) captioning through directed preference optimization (DPO). We propose new metrics to evaluate the completeness and accuracy of video descriptions, which are optimized using DPO. To further improve training, we introduce a novel multi-round DPO (mrDPO) approach, which involves periodically updating the DPO reference model, merging and re-initializing the LoRA module as a proxy for parameter updates after each training round (1,000 steps), and incorporating guidance from ground-truth video captions to stabilize the process. To address potential catastrophic forgetting of non-captioning abilities due to mrDPO, we propose rebirth tuning, which finetunes the pre-DPO LLM by using the captions generated by the mrDPO-trained model as supervised labels. Experiments show that mrDPO significantly enhances video-SALMONN 2's captioning accuracy, reducing global and local erro
We establish connections between the absorption probabilities of a class of birth-death processes with killing, and the stationary tail of a related class of birth-death processes with catastrophes. The major ingredients of the proofs are a decomposition of the dynamics of these processes, a Feynman--Kac type relationship for Markov chains with reset and rebirth, and the concept of Siegmund duality, which allows us to invert the relationship between the processes. We apply our results to a pair of ancestral processes in population genetics, namely the killed ancestral selection graph and the pruned lookdown ancestral selection graph, in a finite population setting and its diffusion limit.