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Decoherence of a quantum magneto-oscillator: Effect of field-bath interaction
(Elsevier BV, 2026-12-15)
Mandal, Koushik
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Bhattacharjee, Suraka
;
Sinha, Supurna
We investigate the quantum dissipative dynamics of a charged magneto-oscillator (CMO) coupled to a heat bath of harmonic oscillators in the presence of an additional field-bath interaction. The problem is formulated within the framework of the generalised quantum Langevin equation, where the external confining potential modifies the random force correlations and the memory kernel of the environment and the spring constant. Using the corresponding non-Markovian master equation, we examine the influence of the field-bath coupling on the temporal decay of the reduced density matrix of the system. We show that the additional interaction leads to an enhancement of the decoherence rate by altering the dissipative response of the bath. Thus our results shed light on the role of field-bath coupling in the quantum to classical transition of a CMO. The resulting fluctuation-dissipation relation is analysed, and the position autocorrelation, position-velocity correlation and velocity autocorrelation are obtained explicitly. The dependence of these experimentally accessible quantities on the field-bath coupling parameter is discussed. We outline an experimental proposal for testing our theoretical predictions. The study sheds light on reservoir engineering which is central to quantum technologies.
Practical limitations on robustness and scalability of quantum Internet
(Springer Science and Business Media LLC, 2026-10-28)
Sadhu, Abhishek
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Somayajula, Meghana Ayyala
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Horodecki, Karol
;
Das, Siddhartha
The realization of a desirably functional quantum Internet is hindered by fundamental and practical challenges such as high loss during transmission of quantum systems, decoherence due to interaction with the environment, and fragility of quantum states under measurement. We study the implications of these constraints by analyzing the limitations on the scaling and robustness of the quantum Internet. Considering quantum networks, we present practical bottlenecks for secure communication, delegated computing, and resource distribution among end nodes. In particular, we show that the device-independent quantum key distribution (DI-QKD) network of isotropic states with parameter p has a finite diameter depending on p. Motivated by the power of abstraction in graph theory (in association with quantum information theory), that allows us to consider the topology of a network of users spatially separated over long distances around the globe or separated as nodes within the small space over a processor or circuit within a same framework, we consider graph-theoretic quantifiers to assess network robustness and provide critical values of communication lines for viable communication over quantum Internet. We consider some quantum networks of practical interest, ranging from satellite-based networks connecting far-off spatial locations to currently available quantum processor architectures within computers, and analyze their robustness to perform quantum information processing tasks. Some of these tasks form primitives for delegated quantum computing, e.g., entanglement distribution and quantum teleportation, that are desirable for all scale of quantum networks, be it quantum processors or quantum Internet.
Impact of a third body on binary neutron star tidal interactions
(American Physical Society (APS), 2026-10-20)
Khatri, Meet
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Renduchintala, Ankur
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Datta, Sayak
;
Mukherjee, Sajal
To model a compact binary coalescence, it is commonly assumed that the binary evolves in isolation. In the present work, we relax this assumption by introducing a distant third body and investigating how the third body would affect the binary evolution. We treat this problem perturbatively and study tidal interaction in the binary due to the third body’s presence. We introduce appropriate modifications to the equations governing the orbital motions and the evolution equations of the binary component’s quadrupole moment. We compute the radiated energy and accumulated dephasing for the binary. Our findings indicate that for extreme-mass-ratio inspirals, these effects would not be significant. However, for binaries such as intermediate-mass-ratio inspirals, these effects are more relevant, and in some scenarios, the accumulated dephasing can reach up to 𝒪⁡(1) radians.
Stellar wind driven Alfvén wing dynamics in planetary and exoplanetary magnetospheres
(Frontiers Media SA, 2026-10-16)
Gupta, Sakshi
;
Basak, Arnab
;
Nandy, Dibyendu
Magnetized obstacles embedded within a plasma flow generate magnetohydrodynamic structures known as Alfvén wings, which act as primary conduits for the transfer of momentum and energy between the body and the surrounding medium. This study employs three-dimensional resistive magnetohydrodynamic simulations to explore how these wings and the magnetosphere respond to diverse stellar wind conditions. Our results, gleaned from a large number of simulations spanning a wide range of stellar wind speed and magnetic field–and planetary dipole field–show that the global magnetospheric configuration is highly sensitive to the upstream Alfvén Mach number. We find that increasing stellar wind speed leads to a systematic closure and narrowing of Alfvén wing structures, while stronger stellar magnetic fields facilitate their opening. Analysis of the Alfvén wing morphology demonstrates a distinct dependence of wing opening angle on stellar wind speed, with internal wing analysis showing a reduction in plasma velocity and significant magnetic-flux accumulation. Our results exhibit a clear interdependence between the day-side magnetopause stand-off distance and the night-side magnetotail current sheet length. We find a linear scaling between the magnetotail dynamics and upstream forcing parameters. This study bridges the gap between solar system observations and (exo)planetary systems by demonstrating how Earth-like magnetospheres might transform into wing-dominated configurations during extreme stellar events or within the sub-Alfvénic regimes of close-in (exo)planets. Our findings can aid the interpretation of Alfvén wing signatures in observational data and enhance our understanding of how (exo)planetary magnetospheres respond to dynamic stellar wind forcing.
MSA-3D: Uncovering Weak Active Galactic Nuclei and Resolved Outflows in Disguise in z ∼ 1 Star-forming Galaxies
(American Astronomical Society, 2026-10-29)
Roy, Namrata
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Henry, Alaina
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Jones, Tucker
;
Barisic, Ivana
;
Sanders, Ryan L
We present spatially resolved rest-optical spectroscopy of 38 star-forming galaxies at 0.5 < z < 1.5 from the JWST/NIRSpec Micro-Shutter Assembly (MSA)-3D survey, which employs a slit-stepping strategy to build integral field unit–like data cubes with a spatial sampling of ∼0.1. We map emission-line morphology, excitation, and kinematics of the warm-ionized gas using [N II]/Hα, [S II]/Hα, and [O III]/Hβ. Relative to z ∼ 0 galaxies at fixed stellar mass, our sources show systematically lower [N II]/Hα and [S II]/Hα and elevated [O III]/Hβ, consistent with harder radiation fields and lower metallicities. Radially, [O III]/Hβ profiles are typically flat or mildly positive, whereas [N II]/Hα also remains flat or declines outward, mirroring metallicity trends. On kiloparsec scales, we find a strong positive correlation between [N II]/Hα and velocity dispersion (σ), linking local excitation to turbulent or shock-driven kinematics. Six galaxies (∼16% of the sample) host spatially localized regions with elevated [N II]/Hα, high EW(Hα), and Vrms V + > 250 km s 2 2 1, indicative of weak active galactic nucleus (AGN) activity, shocks, or outflows. For these candidates, we infer modest warm-ionised outflow rates of 1−4 M⊙ yr−1 and kinetic powers ∼0.1%−1% of the AGN bolometric luminosity (from central [O III] or Hα). These values place our sample at the low-energy tail of known AGN-driven outflows yet in continuity with Mout–LAGN scaling relations across 0 < z < 6. A completeness assessment shows MSA-3D is sensitive to AGN with LAGN ≳ 1043 erg s−1, underscoring both the promise and current limitations of detecting weak AGN activity in distant galaxies with resolved spectroscopy.

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