Persistence of measurement-induced nonlocality in uniformly accelerating Unruh–DeWitt detectors

How does uniform acceleration, which induces the Unruh effect, influence measurement-induced nonlocality (MIN) in a system of two localized Unruh-DeWitt detectors? While previous studies on bosonic field modes suggested that MIN vanishes in the infinite-acceleration limit, this paper investigates whether this suppression is a universal consequence of the Unruh effect or if it depends on the specific physical modeling of the accelerated system.

The authors model two uniformly accelerating two-level detectors (Unruh-DeWitt detectors) coupled to a massless scalar field. By employing the Kossakowski-Lindblad master equation under the Markovian approximation, they derive the stationary state of the detectors. They then analyze how the MIN of this stationary state changes as a function of the Unruh temperature (which is proportional to the acceleration) and the initial correlation parameter of the detector pair.

The study demonstrates that the response of MIN to the Unruh effect is highly sensitive to the initial state of the detectors. Depending on the initial configuration, the authors identify three distinct behaviors: monotonic suppression, where MIN decreases as temperature increases; nonmonotonic behavior, where MIN vanishes at an intermediate temperature and subsequently recovers; and monotonic enhancement, where MIN increases with temperature. Crucially, for a broad class of initial states, MIN approaches a nonzero asymptotic value in the high-temperature limit. This persistence indicates that, unlike entanglement which often suffers from sudden death, MIN captures more robust nonclassical correlations that survive even under strong thermalization.

These findings challenge the notion that acceleration-induced thermal noise universally destroys all forms of quantum correlation. By showing that MIN can be restored or even enhanced by acceleration, the paper highlights that the impact of relativistic motion on quantum information is not solely determined by the Unruh temperature, but is fundamentally shaped by the initial state and the specific dynamics of the quantum probes. This provides a more nuanced understanding of how quantum correlations behave in noninertial frames.