Quantum-to-Classical Transition via Single-Shot Generalized Measurements

TL;DR

This paper links discrete generalized measurements with continuous decoherence, showing that a single measurement round can eliminate nonclassicality faster than traditional decoherence times, offering new insights into quantum-classical transition.

Contribution

It establishes an explicit operational correspondence between measurement rounds and decoherence time, revealing that nonclassicality can vanish abruptly and earlier than standard decoherence times.

Findings

Single measurement round removes quasiprobability negativity.

Critical decoherence time can be shorter than traditional decoherence time.

Provides new insights into quantum-to-classical transition mechanisms.

Abstract

We establish an operational connection between discrete rounds of generalized measurements and continuous-time decoherence, with an explicit correspondence between the number of measurement rounds and the evolution time. Operationally, we show that a single round of such a generalized measurement eliminates quasiprobability negativity in finite-dimensional systems. From the decoherence perspective, this loss of negativity occurs abruptly at a critical time. In particular, this critical time can be shorter than the conventional decoherence time, indicating that the latter does not always faithfully track the disappearance of nonclassicality. Our results provide new insight into the quantum-to-classical transition in finite-dimensional systems from the viewpoint of phase-space quasiprobability, and suggest feasible quantum-circuit tests as well as possible heralded resource extraction from noise.