dekoherents

Dekoherents are the components of a quantum system that have become decoherent due to interaction with an environment. In this usage, a dekoherent state is one whose reduced density matrix is approximately diagonal in a preferred, or pointer, basis, meaning that quantum interference between different alternatives is effectively suppressed. Decoherence is the dynamical process that drives this transition, as the environment monitors certain system observables and rapidly damps the off-diagonal elements of the system's density matrix.

The mechanism of decoherence begins when the system becomes entangled with many environmental degrees of freedom. After tracing out the environment, the reduced density matrix of the system loses coherence between states that are distinguishable by the environment. The surviving states form the pointer basis, in which the density matrix is diagonal or nearly diagonal. The rate and the basis depend on the system-environment coupling and dynamics.

Interpretation and implications: Dekoherents underpin the appearance of classical properties in quantum systems. They are not a literal collapse, but an effective suppression of interference that makes distinct alternatives behave like a classical statistical ensemble. In ideas such as quantum Darwinism, information about the dekoherent, pointer states is redundantly recorded in the environment, allowing independent observers to concur on the outcome without perturbing it.

Terminology and example: The phrase "dekoherents" appears in some German-language texts; English-language literature usually uses "decohered states" or simply describes decoherence. For example, a qubit interacting with a thermal bath can exhibit phase damping, causing the off-diagonal elements in the qubit density matrix to decay as e^{-Γ t}, while the populations remain fixed.