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Frontiers in Physics

The Quantum Coherence Induced by Geometric Curvature of Gauge Field in Non-equilibrium Quantum Dynamics

Haidong Feng, Jin Wang

Published May 13, 2020• 1 citation
Publisher

Abstract

The study of non-equilibrium quantum dynamics receives attentions recently. However, the nature and effects of nonequilibirumness such as detailed-balance breaking and the relationship to the underlying intrinsic geometry is still unclear. In this study, we uncover that a gauge field will be induced by the nonequilibriumness in the coherence representation and furthermore its internal geometrical curvature is directly related to the degree of detailed balance breaking. The nonequilibriumness of the quantum system induces an intrinsic geometric curvature which can enhance the quantum coherence, leading to the possibility of the space time origin for the non-local quantum correlations or the possibility of curved space time emergence from nonequilibrium quantum dynamics. We also uncovered that the internal curvature of the gauge field provides a bridge to connect the generalized quantum fluctuation dissipation theorem to the fluctuation theorem and time irreversibility of the quantum dynamics. The quantum time irreversibility is due to the path dependent factor along any particular path in an internal curved space, which is analogous to the Wilson lines (or Wilson loops) in Abelian gauge theory. We also found that the steady state quantum coherence disappears when the non-trivial internal curvature vanishes for the quantum system coupled with environments. When the curvature is relatively small indicating weak detailed balance breaking, the coherence increases as curvature increases. The internal curvature can provide a general and direct quantitative measure of the detail-balance breaking for any quantum/classical non-equilibrium systems, even without knowing the underlying steady state distribution or the steady state flux. Using an example of two harmonic oscillators coupled to two environments with different temperatures, we explicitly show the dependence of the internal curvature and quantum coherence.

DOI
10.3389/fphy.2020.00129

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The study of non-equilibrium quantum dynamics receives attentions recently. However, the nature and effects of nonequilibirumness such as detailed-balance breaking and the relationship to the underlying intrinsic geometry is still unclear. In this study, we uncover that a gauge field will be induced by the nonequilibriumness in the coherence representation and furthermore its internal geometrical curvature is directly related to the degree of detailed balance breaking. The nonequilibriumness of the quantum system induces an intrinsic geometric curvature which can enhance the quantum coherence, leading to the possibility of the space time origin for the non-local quantum correlations or the possibility of curved space time emergence from nonequilibrium quantum dynamics. We also uncovered that the internal curvature of the gauge field provides a bridge to connect the generalized quantum fluctuation dissipation theorem to the fluctuation theorem and time irreversibility of the quantum dynamics. The quantum time irreversibility is due to the path dependent factor along any particular path in an internal curved space, which is analogous to the Wilson lines (or Wilson loops) in Abelian gauge theory. We also found that the steady state quantum coherence disappears when the non-trivial internal curvature vanishes for the quantum system coupled with environments. When the curvature is relatively small indicating weak detailed balance breaking, the coherence increases as curvature increases. The internal curvature can provide a general and direct quantitative measure of the detail-balance breaking for any quantum/classical non-equilibrium systems, even without knowing the underlying steady state distribution or the steady state flux. Using an example of two harmonic oscillators coupled to two environments with different temperatures, we explicitly show the dependence of the internal curvature and quantum coherence.
Classical thermodynamics admits a geometric formulation in which work is associated with areas enclosed by cycles in state space. Whether an analogous structure persists in driven, dissipative quantum systems remains an open question. Here we show that quasistatic work in open quantum steady states is governed by an emergent geometric curvature in control-parameter space arising from steady-state coherence. For a driven dissipative two-level system, we construct a work one-form whose curvature determines the work produced in cyclic processes. The work vanishes under strong dephasing, identifying coherence as a necessary condition for nontrivial geometry. However, its magnitude is set not by the coherence itself but by the spatial structure of the curvature: cycles enclosing comparable areas produce different work depending on their location in parameter space. Reversing the cycle orientation reverses the sign of the work, confirming its geometric origin. These results establish a geometric framework for open quantum thermodynamics and identify curvature as the organizing principle of thermodynamic response, with direct implications for driven light--matter systems in cavity quantum electrodynamics.
We formulate a geometric framework for quasistatic thermodynamics in open quantum systems by parameterizing the dynamics on a control manifold. In the quasistatic limit, the system follows a manifold of stationary states, and the work performed over a cycle is given by the flux of a curvature two-form, W∼∫ΩW \sim \int ΩW∼∫Ω, defined by the parametric response of the stationary state, establishing an open-system analog of classical thermodynamic area laws. \erbedit{For thermal stationary states at fixed temperature, the curvature vanishes, reflecting the integrability of the work one-form.} Beyond this limit, nonequilibrium stationary states can retain coherence in the energy representation; using a fixed-basis Lindblad model, we show that this coherence reshapes the curvature, making it anisotropic and sign-changing, so that work depends sensitively on the placement and orientation of the cycle. Quantum coherence, therefore, partitions the control manifold into regions of opposite curvature, producing geometric cancellation of work and allowing the net work over a cycle to be reduced or reversed despite dissipative dynamics. Thermodynamic work thus emerges as a curvature flux whose structure is set by thermodynamic response in classical systems and by basis misalignment between the Hamiltonian eigenbasis and the environment-selected pointer basis in open quantum systems.
Abstract We introduce a phase-geometric framework in which time evolution is governed by a covariant derivative defined over a multi-carrier phase space. The associated connection induces a non-abelian curvature whose holonomy generates measurable phase-transport effects. Within this unified geometric setting, the quantum–classical transition, phase-channel mixing, and time-transport anomalies arise from a single underlying mechanism. In contrast to conventional approaches, where gauge structures are imposed externally, the connection emerges intrinsically from the phase geometry itself. The framework yields calculable thresholds for classicalization and leads to novel, testable predictions based on curvature-induced phase holonomy.
We develop a response-geometric framework for open quantum systems by decomposing the stationary-state response tensor into symmetric and antisymmetric sectors. The symmetric sector defines a metric-like response tensor governing local susceptibility, while the antisymmetric sector defines a curvature two-form associated with nonreciprocal response and geometric work. We show that the work curvature is precisely the antisymmetric component of the response tensor, establishing a fluctuation--response relation that extends the geometric structure of equilibrium thermodynamics to nonequilibrium steady states, and reveals a response geometry with both metric and symplectic sectors. In equilibrium, the antisymmetric sector vanishes by reciprocity, recovering the familiar metric geometry of thermodynamic response. Open quantum systems admit a broader structure in which reciprocal and nonreciprocal responses coexist on the same control manifold. We illustrate this with a driven dissipative qubit under pure dephasing, where finite curvature emerges from the misalignment between the Hamiltonian eigenbasis and the pointer basis selected by the environment, without requiring strong driving or engineered reservoirs. Comparison with the Bures metric shows that response geometry and information geometry characterize distinct properties of the stationary-state manifold: the former governs susceptibility and geometric work, the latter quantifies state distinguishability. Geometric work thus emerges as a measurable signature of nonreciprocal response in open quantum systems.
Quantum mechanics is conventionally formulated on complex Hilbert spaces, whereas gauge theories are formulated through connections, holonomies, and curvature. Despite their common use of complex structures, the geometric relationship between these frameworks remains incompletely understood. In this work, we develop a geometric interpretation of the Triple-Coherence Framework based on the complex coherence coordinate Z=M+iQ . The empirical Triple-Coherence relation is reformulated as an exponential generator structure, naturally leading to a discrete coherence lattice. Combining this radial structure with an angular phase coordinate yields the representation Z=R exp i(phi). We investigate the possibility that the MQ plane constitutes a more fundamental geometric arena than the conventional Hilbert-space description of quantum mechanics. Within this framework, quantum states correspond to points on an MQ manifold, Hilbert spaces emerge as function spaces on this geometry, and Yang–Mills holonomies generate the phase structure of quantum states. The resulting formulation provides a common language connecting Triple-Coherence coordinates, Schrödinger dynamics, Wilson loops, gauge transport, and particle stability.
The process of quantum measurement is known to induce decoherence in the measured system. In this work we propose that the rate of decoherence, denoted by γ, can be expressed as a function of the geometric properties of the underlying quantum state manifold, γ = f(G). Here G represents a scalar or tensorial quantity that quantifies the curvature, volume, or other intrinsic geometrical features of the state space. We develop a general framework that connects the measurement operators, the dynamical evolution of the density matrix, and the geometry of the space of pure states. By treating the measurement process as a stochastic dynamical map acting on the Bloch sphere for two-level systems and on the complex projective space CP^(N−1) for N-level systems, we derive explicit forms of f(G) that depend on the sectional curvature and the Fubini–Study metric. The resulting theory predicts that states situated in highly curved regions of the state space will exhibit accelerated decoherence compared to states in flatter regions. This geometric damping mechanism offers a novel perspective on the measurement problem and suggests new strategies for protecting quantum coherence by engineering state-space geometry. The potential for a Nobel Prize arises from the fundamental shift in understanding that geometry, rather than only dynamics, can control quantum measurement outcomes.