arXiv subjects

Ovidiu I. Pâţu

Publications and source records attributed to Ovidiu I. Pâţu.

4 recordsLinked to original sources

arXiv2026

Robust Spin Universality Across a Ballistic-to-Diffusive Transport Crossover

Whether a full counting statistical distribution preserves its universality class across a coherent-to-incoherent crossover is a fundamental question in open quantum systems. We resolve this for the infinite-$U$ Hubbard chain, showing that local density dephasing changes transport exponents without destroying the underlying non-Gaussian M-Wright spin fluctuations. Utilizing the exact spin-charge composition law inherent to impenetrable dynamics, we track the charge sector from ballistic flow to diffusive hydrodynamics. This dissipative crossover shifts the characteristic spin-transfer width from $t^{1/4}$ to $t^{1/8}$. Despite this altered scaling time, the central spin characteristic functions uniformly collapse onto a singular M-Wright scaling function, what we confirm using analytics as well as numerics.

cond-mat.quant-gas↗

arXiv2026

Spin-Charge Subordination in the Infinite-$U$ $SU(N)$ Hubbard Chain

We obtain the exact full counting statistics of charge and flavor transport in the one-dimensional infinite-$U$ $SU(N)$ Hubbard model. The no-passing constraint freezes the ordered flavor sequence while the particle coordinates evolve as free spinless fermions. Consequently, charge transfer is governed by a free-fermion determinant, whereas flavor transfer is exactly subordinated to the number of particles crossing the observation cut. For an arbitrary traceless Cartan generator this yields an exact relation between the charge and flavor cumulants. The complete asymptotic flavor distribution is a universal non-Gaussian M-Wright law. Together, these results establish spin--charge subordination as a kinematic mechanism for anomalously slow internal-state transport in one-dimensional impenetrable quantum gases.

cond-mat.quant-gas↗

arXiv2026

Interaction-induced asymmetry in infinite-temperature dynamical correlations of hard-core anyons

We study dynamical correlations of interacting hard-core anyons on a one-dimensional lattice at infinite temperature. This is a setting in which the many-body spectrum is independent of the statistical phase $θ$, while dynamical correlators remain sensitive to $θ$ through nonlocal Jordan-Wigner strings. We compute single-particle Green's functions, spectral functions, and density-density correlators, thereby separating the effects of fractional statistics on one-body coherence from those on density transport in a maximally mixed ensemble. In the noninteracting case $V=0$, high-temperature averaging leads to inversion-symmetric Green's functions for all $θ$ despite the presence of anyonic strings. Finite nearest-neighbor interactions $V$ generate, however, a pronounced left-right asymmetry in the Green's functions for $0<θ<π$, with the strongest chirality appearing at intermediate couplings $V\sim J$ where interactions and hopping compete most effectively. In this regime, the Green's function decays exponentially in time with a statistical-angle-dependent decay rate. At strong coupling, the dynamics crosses over to an atomic-limit regime in which the dependence on $θ$ is reduced. Here, the Green's function decays universally as $t^{-1}$ and the corresponding spectral function displays a three-band structure. In contrast, density-density correlations are insensitive to statistics and recover the known infinite-temperature transport regimes of the XXZ chain, including ballistic, superdiffusive, and diffusive behaviors. These results identify dynamical correlation functions as direct probes of fractional statistics in high-entropy quantum systems.

cond-mat.str-el↗

arXiv2026

Dynamical correlations in a dissipative XXZ spin chain

We study dynamical spin correlations in a dissipative XXZ spin chain subject to uniform local spin-loss and pumping. Starting from a mixed steady state that is featureless albeit possessing finite magnetization, rich dynamics emerges in time-dependent two-point correlators evaluated on top of it. For unitary evolution in which the reservoir is absent, the longitudinal correlators reproduce the established hierarchy of spin-transport universality classes - ballistic, Kardar-Parisi-Zhang (KPZ) superdiffusive, and diffusive - across the phase diagram. However, for finite magnetization, additional ballistic light cone propagation gets superimposed on the previous universality classes, arising from magnon propagation.The transverse correlator displays very fast, exponential decay of correlations without wavefront propagation in the easy-plane case. At the isotropic point, it follows KPZ scaling due to $SU(2)$ symmetry, while in the easy-axis regime, it is characterized by ballistic spreading of correlations. Under full Lindbladian dynamics, the universality classes are preserved at early times, while the correlations acquire an overall exponential damping in the long-time limit. In terms of methods, we have used vectorized TEBD for numerical simulations and exact analytical results obtained via a Pfaffian representation and the third-quantization framework for the noninteracting XX case.

cond-mat.str-el↗