arXiv subjects

Daoguang Li

Publications and source records attributed to Daoguang Li.

2 recordsLinked to original sources

arXiv2026

Kardar--Parisi--Zhang density hydrodynamics in a coherent XXZ--ASEP Lindbladian

Coherent interactions can generate quantum correlations without changing a stationary density current. Whether that current still determines long-wavelength transport is a dynamical question. We study an XXZ chain with asymmetric Lindblad hopping, whose stationary current has the asymmetric simple exclusion process (ASEP) form although its populations do not evolve autonomously. The current curvature and static susceptibility fix the leading Kardar--Parisi--Zhang (KPZ) length and amplitude without a fitted length or amplitude conversion factor. The density-visible Liouvillian spectrum, real-space spreading, and Fourier relaxation support KPZ scaling at the finite coherent couplings studied. Central and intermediate stationary density correlations are consistent with the Prähofer--Spohn profile at this microscopic scale, with resolved finite-time corrections. Reservoir-matched classical references quantify boundary effects, while symmetric hopping recovers diffusion and reduced asymmetry produces the expected crossover. These results connect an exact nonlinear current to the observed long-wavelength KPZ transport of the physical density in an interacting open quantum chain away from the isotropic Heisenberg point.

cond-mat.stat-mech↗

arXiv2026

Hilbert-space fragmentation selects channels of strong-to-weak spontaneous symmetry breaking

Strong-to-weak spontaneous symmetry breaking (SWSSB) can occur in a maximally mixed charge sector even when ordinary charged correlations vanish. We study this order when a charge sector splits into dynamically disconnected fragments. In a one-dimensional $t$-$J_z$ chain with species-resolved dephasing, each fragment is labeled by a conserved spin word. A charged transfer between separated finite intervals preserves that word only if the intervening spins satisfy a periodicity constraint. In the full-state two-point sense, we use this constraint to prove the absence of long-range fidelity and Rényi-1 order in typical fixed-composition fragments, uniformly over all norm-bounded charged operators in any prescribed finite interval. A fragment with primitive spin-word period $k$ supports a $k$-particle channel with exact long-distance value $ν^k(1-ν)^k/k^2$, and no charged operator on fewer than $k$ sites can carry this order. A transverse exchange connects the fragments while preserving the global charges and restores the full-sector steady state at finite size. The conserved spin word therefore selects the local channels that can support mixed-state order.

quant-ph↗