2026-10-15 · arXiv Quantum Physics
arXiv:2510.10394v4 Announce Type: replace
Abstract: We consider a class of nonunitary operations that is naturally implemented via a combination of projective measurement and unitary operators. We implement these operations without using measurements by coupling the system to an infinite set of ancilla states and time-evolving with a single time-independent Hamiltonian. The infinite ancilla enables the main system to reach a local steady state that preserves initial phase information. We prove that these steady-state operations are not describable as a mapping from an initial state to a steady state of a time-independent Lindblad master equation acting only on the main system. As an additional degree of control, we show that the spectral resonance between the system and the ancilla acts as a switch that turns the operation on and off, and we derive a closed-form expression that quantifies the sharpness of this switch. We further find numerically that the phase preservation survives moderate disorder, over a time window set by the size of the ancilla. This Hamiltonian framework therefore provides a route to autonomous quantum control using the tunability of a closed system.
原文链接：https://arxiv.org/abs/2510.10394
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