coherencespecific

Coherencespecific is an adjective used in quantum information science to describe properties, processes, or measures that depend on quantum coherence with respect to a chosen reference basis. It refers to phenomena driven by nonzero off-diagonal elements in a system’s density matrix and that would vanish if the coherence were eliminated by dephasing. The term highlights the basis dependence of coherence: a coherencespecific effect can exist in one basis and be absent in another.

In the resource theory of coherence, coherencespecific quantities quantify how a quantum operation changes coherence. Measures such as the l1-norm of coherence or the relative entropy of coherence are used to assess a channel’s effect on off-diagonal terms. A process may be described as coherence-generating if it increases these measures for some inputs, or coherencespecific in the sense that its action can only be understood by tracking coherence.

Coherencespecific operations are those that act nontrivially on off-diagonal elements while leaving populations largely intact, or that modify coherence in ways not captured by changes in populations alone. Dephasing channels reduce coherence and are typically not viewed as coherencespecific, since they suppress off-diagonal terms.

Applications of coherencespecific analysis appear in quantum computation, quantum metrology, and quantum thermodynamics, where the presence and manipulation of coherence influence performance, precision, or efficiency.

See also: Quantum coherence; Resource theory of coherence; Dephasing; Quantum channels.