arXiv subjects

Arseny Pantsialei

Publications and source records attributed to Arseny Pantsialei.

4 recordsLinked to original sources

arXiv2026

Center-of-Mass Bounds and Harmonic Extremality

We study the center-of-mass observable in one-dimensional many-body systems with translation-invariant interactions and extend the harmonic-rigidity mechanism from the one-body setting to an interacting many-body problem. We prove a sharp upper bound on the ground-state center-of-mass fluctuation in terms of the active spectral gap associated with the center-of-mass probe, and show that this bound does not require any positivity assumption on the ground state. In the positivity class, we characterize the equality case completely. Exact saturation occurs if and only if the external one-body traps are harmonic with a common frequency, while the interaction may remain arbitrary within the translation-invariant class. We also identify a natural rigidity defect measuring deviation from the harmonic extremal situation and prove quantitative near-saturation estimates controlling both the variance deficit and the spectral weight outside the first active shell. In this way, the paper establishes harmonic confinement as the unique static extremizer for the rigid interacting center-of-mass mode at fixed active gap.

quant-ph↗

arXiv2026

A Descriptor Surrogate for Kerr Shadow Contours

We consider the Kerr black hole shadow contour as a geometric object whose essential shape can be captured by a small set of physically transparent descriptors. Starting from exact critical-curve calculations, we map each contour to a centered radial profile and retain five quantities: the mean radius, the horizontal centroid shift, and three low-order harmonic coefficients. In this way, the aim is to obtain a compact contour-level representation suitable for repeated evaluation and systematic comparison. We then build a boundary-aware surrogate over spin and inclination that recovers the correct circular limits near the Schwarzschild and polar boundaries and includes a simple positivity safeguard for the reconstructed radial profile. On a held-out bulk domain with inclinations i >= 5°, the production surrogate yields median errors of 0.522% in contour area, 0.261\% in equivalent diameter, and 0.954% in the 95th-percentile radial contour mismatch; the corresponding 95th-percentile errors are 1.100%, 0.551%, and 3.436%, with no negative-radius samples. The exact descriptor reconstruction is already accurate at the sub-percent level for area and equivalent diameter, which shows that the descriptor layer is a meaningful compression of the contour geometry. We also show that contours with nearly identical equivalent diameter can remain visibly distinct, so the retained descriptors encode geometric information beyond a single size observable. The resulting model provides a compact and interpretable contour-level surrogate for parameter scans and repeated contour comparisons in the Kerr problem.

gr-qc↗

arXiv2026

Torsion Induced Asymmetric Luttinger Liquids

We consider a general model of a Luttinger liquid with broken parity and time reversal symmetry, but with their composite symmetry intact. Such a scenario can be due to a combination of torsion and a Zeeman field in nanowires, or a result of bringing different helical Luttinger liquids into proximity. The broken symmetries result in a band structure with no axis of symmetry, and therefore with asymmetric velocities between left and right moving contributions. By taking a general spin-full model with all possible scattering and interaction terms in the bosonic model we show that generically the spin degree of freedom becomes gapped out, resulting in an effective spinless Luttinger liquid with asymmetric velocities. Our work generalizes and extends previous studies which focused on a minimal model of a spinless Luttinger liquid. We further demonstrate that a possible experimental signature of the asymmetry of such asymmetric models can be seen in the spectral function.

cond-mat.str-el↗

arXiv2025

Harmonic rigidity at fixed spectral gap in one dimension

We solve the static isoperimetric problem underlying the Mandelstam-Tamm bound. Among one-dimensional confining potentials with a fixed spectral gap, we prove that the harmonic trap is the unique maximizer of the ground-state position variance. As a consequence, we obtain a sharp geometric quantum speed-limit bound on the position-position component of the quantum metric, and we give a necessary-and-sufficient condition for when the bound is saturated. Beyond the exact extremum, we establish quantitative rigidity. We control the Thomas-Reiche-Kuhn spectral tail and provide square-integrable structural stability for potentials that nearly saturate the bound. We further extend the analysis to magnetic settings, deriving a longitudinal necessary-and-sufficient characterization and transverse bounds expressed in terms of guiding-center structure. Finally, we outline applications to bounds on static polarizability, limits on the quantum metric, and benchmarking of trapping potentials.

quant-ph↗