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ABSTRACT Environmental noise is harmful to quantum technologies, but structured environments can temporarily store and return information, producing useful memory effects. We study this mechanism in a microscopic qubit pseudomode model, where a qubit couples to a single damped mode. Although the enlarged qubit–pseudomode dynamics is Markovian, the reduced qubit channel crosses from CP‐divisible‐like to CP‐indivisible‐like regimes as the coupling , damping , and detuning are varied. Using a trace‐distance backflow proxy together with the amplitude‐damping CP‐divisibility criterion, equivalently Choi positivity of intermediate maps, we construct a finite‐window memory map. The backflow proxy is a restricted diagnostic based on selected state pairs, not a faithful estimate of the optimized BLP measure. This map organizes two task‐level benchmarks. In hybrid qubit–qutrit transmission, we use an established RHP‐type entanglement‐revival benchmark; the qutrit is only a passive embedded reference, and qubit–qubit checks confirm channel‐level revivals. In detuning metrology, the quantum Fisher information provides multiple interrogation windows under a time‐budgeted two‐time protocol with the same channel uses as a single‐time baseline. The protocol assumes ideal fresh environments with no reset‐time cost. Overall, the results link pseudomode memory to entanglement preservation and parameter estimation without claiming a full resource theory.
Jaradat et al. (Wed,) studied this question.