This work investigates the emergence of state-dependent dissipative structures in open quantum systems and develops a geometric framework for constructing physically admissible non-linear extensions of Markovian quantum dynamics. Building upon the coarse-grained completely positive generators developed in previous work, we consider the effects of finite and dynamically polarizable environments, leading naturally to state-dependent Kossakowski structures and non-linear dissipative flows. To constrain such non-linear dynamics and prevent the appearance of unphysical states, we formulate the evolution as a gradient flow on the manifold of quantum states endowed with the Bures metric. A locality-preserving Extension Consistency Condition is introduced to ensure the admissibility of non-linear lifts to composite systems and to eliminate non-local ancillary back-action. Within this framework, we establish a Boundary Repulsion Theorem showing that the rank-deficient boundary of the positive state manifold is located at an infinite geometric distance along the flow trajectories. As a consequence, positivity of the density operator is preserved for all finite evolution times. A worked example based on a three-level V-system demonstrates the regularizing effect of the Bures geometry in the presence of state-dependent dissipation. The results suggest that information-geometric structures may provide a natural route toward physically consistent non-linear quantum master equations while preserving the operational integrity of quantum state evolution.
This work investigates the emergence of state-dependent dissipative structures in open quantum systems and develops a geometric framework for constructing physically admissible non-linear extensions of Markovian quantum dynamics. Building upon the coarse-grained completely positive generators developed in previous work, we consider the effects of finite and dynamically polarizable environments, leading naturally to state-dependent Kossakowski structures and non-linear dissipative flows. To constrain such non-linear dynamics and prevent the appearance of unphysical states, we formulate the evolution as a gradient flow on the manifold of quantum states endowed with the Bures metric. A locality-preserving Extension Consistency Condition is introduced to ensure the admissibility of non-linear lifts to composite systems and to eliminate non-local ancillary back-action. Within this framework, we establish a Boundary Repulsion Theorem showing that the rank-deficient boundary of the positive state manifold is located at an infinite geometric distance along the flow trajectories. As a consequence, positivity of the density operator is preserved for all finite evolution times. A worked example based on a three-level V-system demonstrates the regularizing effect of the Bures geometry in the presence of state-dependent dissipation. The results suggest that information-geometric structures may provide a natural route toward physically consistent non-linear quantum master equations while preserving the operational integrity of quantum state evolution.
We formulate a geometric extension of open quantum dynamics in which the density matrix evolves as a Riemannian gradient flow on the Bures manifold. The evolution equation \frac{d\rho}{dt} = -i[H,\rho] - \lambda \nabla_B \Phi[\rho] drives the state toward regions of minimal information degradation, defined by the functional \Phi[\rho], the instantaneous rate of relative-entropy change under the bare Lindbladian. This deterministic flow preserves trace and positivity, and introduces a single new universal constant \lambda>0 while recovering standard Lindblad dynamics as \lambda\to0. Under a Unitary Orthogonality Condition – exactly satisfied for pure dephasing and approximately in many-body localized phases – \Phi becomes a Lyapunov functional, and its critical points (decoherence-free subspaces) are asymptotically stable attractors. Applied to disordered spin chains, the framework reproduces the known entropy‑suppression scaling \Phi \lesssim \gamma N (J/W)^2. The theory offers a falsifiable, information‑geometric principle where quantum states intrinsically minimise their own information loss. Keywords: quantum information geometry, Bures metric, gradient flow, Lindblad dynamics, decoherence-free subspaces, many-body localization, Lyapunov functional
In this work, we present a geometrical formulation of quantum thermodynamics based on contact geometry and principal fiber bundles. The quantum thermodynamic state space is modeled as a contact manifold, with equilibrium Gibbs states forming a Legendrian submanifold that encodes the fundamental thermodynamic relations. A principal fiber bundle over the manifold of density operators distinguishes the quantum state structure from thermodynamic labels: its fibers represent non-equilibrium configurations, and their unique intersections with the equilibrium submanifold enforce thermodynamic consistency. Quasistatic processes correspond to minimizing geodesics under the Bures-Wasserstein metric, leading to minimal dissipation, while the divergence of geodesic length toward rank-deficient states geometrically derives the unattainability aspect of the third law. Non-equilibrium extensions, formulated through pseudo-Riemannian metrics and connections on the principal bundle, introduce curvature-induced holonomy that quantifies a geometric source of irreversibility in cyclic processes. In this framework, the thermodynamic laws in the quantum regime emerge naturally as geometric consequences.
This paper develops a rigorous, self-contained differential-geometric framework for tracking mixed quantum states in open physical systems, providing an analytical structural extension to the pure-state Kâhler geometry of Paper 1. Because open quantum dynamics induced by environment-driven dissipation and decoherence break the global manifold homogeneity, we model the total space of density operators S(H) as a stratified space. We prove that the individual rank-k subsets constitute embedded smooth real manifolds of dimension 2k(N + 1) − k2 − 1, satisfying the algebraic conditions of Whitney Regularity Condition B to guarantee continuous tangent space alignment across interfaces. To assign coordinate-independent connection and metric tensors over this stratified landscape, we formalize the global principal U (n) fiber bundle structure using Uhlmann’s purification theorem. By lifting mixed density operators to pure-state amplitudes W ∈ GL(n, C) on a bipartite workspace, we show that minimizing the ambient flat Hilbert–Schmidt metric along the vertical fibers induces the non-degenerate Bures metric on the base manifold. We derive the exact matrix elements of the corresponding Symmetric Logarithmic Derivative (SLD) fields in an arbitrary non-degenerate eigenbasis, establishing the mixed-state information scaling boundary gQF IM = 4gB. Finally, we characterize the non-Abelian Yang–Mills curvature FU = dAU + AU ∧ AU of the Uhlmann connection, demonstrating how non-commutativity emerges naturally under environmental coupling. By isolating the measure-zero boundary configurations where eigenvalues or matrix rank drop, we generalize our control immersion criterion to identify both rank deficient and eigenvalue-vanishing caustic singularities. This metric-determinant verification pipeline allows researchers to systematically diagnose, map, and structurally bypass trajectory bottlenecks during Lindbladian control path optimization on real-world noisy quantum backends
We develop a Lie-Jordan geometric formulation of finite-dimensional open quantum dynamics, building on the algebraic framework introduced in our previous work (arXiv:2606.26477). The Hilbert-Schmidt operator space is endowed with an orthonormal Hermitian basis, in which the commutator and anticommutator are encoded by the structure tensors Cμνλ and Bμνλ. Within this formulation, the von Neumann and Gorini-Kossakowski-Lindblad-Sudarshan equations admit a direct component representation. Our central result is the identification of a basis-independent universal trilinear dissipative map, D(X,Y)Z=XZY−21{YX,Z}, whose components define a universal operator-space tensor depending only on the Lie-Jordan structure tensors. The physical dissipator is obtained by contracting this tensor with the expansion coefficients of the Lindblad operators and the Kossakowski matrix, thereby separating the universal algebraic structure from the model-dependent physical information. We further show that the combinations (B+C) and (B−C) generate internal left and right transports, allowing the elementary dissipative map to be expressed as a left-right bimodule action corrected by an ordered Jordan contribution. The universal map satisfies basis-independent trace and Hermitian-conjugation identities, from which trace preservation, Hermiticity preservation of the complete dissipator, and the reality of its component representation in a Hermitian Hilbert-Schmidt basis follow. We also derive its Hilbert-Schmidt adjoint and illustrate the formalism for a qubit with pure dephasing and amplitude-damping channels. This construction provides a tensorial and affine-geometric interpretation of the universal superoperator structure derived in arXiv:2606.26477 while keeping the algebraic and model-dependent sectors explicitly separated.
The second law does more than set the direction of thermodynamic evolution: it endows nonequilibrium transformations with an underlying geometry. In this work, we provide a unified geometric description of entropy production in classical and quantum thermodynamics based on Wasserstein-2 structures arising from gradient flows of free energy. We review how relaxation to equilibrium, in overdamped diffusions, discrete detailed-balanced Markov chains, and dissipative Lindblad dynamics, can be formulated as a gradient flow on the space of states. The associated Wasserstein-2 distance bounds entropy production, yielding a finite-time refinement of the second law. We extend this framework beyond purely dissipative dynamics by introducing generalized Wasserstein-2 metrics that incorporate conservative (Hamiltonian) dynamics in both classical inertial systems and open quantum systems, yielding intrinsic distances that exactly characterize minimal entropy production under fixed dissipative mobilities. We establish equivalence bounds between purely dissipative and Hamiltonian-dissipative geometries, explicitly quantifying how inertial or coherent dynamics can reduce dissipation. Finally, when restricted to equilibrium distributions, we recover the thermodynamic length of linear response-including the quantum thermodynamic length-thereby linking optimal transport, thermodynamic length, and counterdiabatic protocols within a single geometric framework. All in all, our results extend the Riemannian program of thermodynamics further from equilibrium and provide a geometric foundation for optimal protocols beyond the overdamped setting.
The Emergent Spacetime program (Informational Geometry of Emergent Spacetime – IGES) has shown that the linearized Information Open-systems Flow (IOF) on the Bures manifold of density operators projects to a symmetric hyperbolic hydrodynamic system whose characteristic cone is exactly Lorentzian. This established that spacetime causal structure can emerge from quantum information degradation, but only in the tangent-space approximation. In this work, we address the principal remaining gap: we provide strong numerical evidence for a Nonlinear Emergent Causal Structure Scenario, supporting the conclusion that an effective hyperbolic causal cone acts as a dynamically stable attractor of the full, nonlinear IOF dynamics. We implement a complete numerical simulation of two coupled qubits with dephasing on a 1D lattice, evolving the exact IOF on the 15-dimensional Bures manifold. At each time step we extract the Bures Hessian of the information degradation functional, construct the dynamic spectral gap ∆(t), compute the nonlinear Schur complement Keff(t), and measure the instantaneous cone deviation δ(t) ≡ supk |ω 2 (t, k) − c 2 s(t)k 2 |. We find that: (1) the fast/slow mode separation persists globally; (2) the spectral gap remains strictly positive, ∆(t) ≥ ∆0 > 0; (3) the effective reduced generator Keff(t) remains symmetric in the Bures metric to machine precision; (4) the cone deviation δ(t) decays as e −∆t , falling below 10−4 after a few gap times. These results provide significant evidence that the emergent hyperbolic causal structure is not a linear artifact – the effective causal cone is a robust attractor of the full gradient flow. This nonlinear stability suggests compatibility with Jacobson-type thermodynamic gravity scenarios. The complete simulation code and diagnostic data are provided as supplemental material.