likevektskvantum

Likevektskvantum is a theoretical construct in physics and speculative literature that denotes a quantum state of a many-body system that is in thermodynamic equilibrium while maintaining nontrivial quantum coherence and correlations at macroscopic scales. The term derives from the Norwegian word for equilibrium, likevekt, combined with kvantum, and is used to characterize states where standard decoherence arguments do not fully erase phase relations during equilibration.

In conventional quantum statistical mechanics, equilibrium states are described by a Gibbs density operator rho_eq = e^{-βH}/Z for a closed system at temperature T, or by a generalized ensemble when additional conserved quantities are relevant. Likevektskvantum emphasizes the possibility that certain off-diagonal elements in the energy basis or in a chosen observable basis remain appreciable under equilibration, leading to measurable coherences in stationary conditions. In practice, such states are discussed mainly in the context of integrable systems, weakly coupled baths, or specific initialization protocols that suppress complete thermalization. Mathematically, they may be modeled by a restricted density operator that maximizes entropy subject to a set of conserved quantities or constraints that permit residual coherence.

Status and usage: The concept is not standard in mainstream quantum mechanics and is primarily found in speculative discussions, pedagogical thought experiments, or science fiction-influenced analyses. Researchers typically describe equilibrium quantum behavior with conventional ensembles or with generalized ensembles (GGE) without invoking a separate category called likevektskvantum.

See also: quantum thermodynamics, Gibbs state, generalized Gibbs ensemble, decoherence, stationary state.