Covariant measures of non-Markovianity in curved spacetime
Year: 2026
Type: article
Abstract: Standard diagnostics of quantum non-Markovianity are commonly formulated in terms of dynamical maps defined on a preferred time foliation. This becomes conceptually and operationally ambiguous in curved spacetime, where no global time coordinate exists and causal structure is primary. We develop a covariant framework for open quantum dynamics along arbitrary timelike worldlines by constructing multi-time processes (process tensors) from overlapping causal diamonds. For an Unruh–DeWitt detector weakly coupled to a scalar field in a Hadamard state, we quantify memory by the operational distance between the resulting process tensor and the convex set of Markovian (CP-divisible) combs, yielding a foliation-independent measure of non-Markovianity. Numerical benchmarks in ( 1 + 1 ) dimensions compare inertial and uniformly accelerated motion, as well as static and infalling trajectories in Schwarzschild spacetime. Inertial motion is nearly Markovian, whereas acceleration, curvature, and horizons generate long-range temporal correlations and strong multi-time memory, including an activation gap: effects that remain weak in single-step diagnostics become detectable and can be enhanced by genuinely multi-time protocols. Our results provide an operational route to quantifying quantum memory in relativistic settings and identify acceleration, curvature, and horizons as controllable ingredients for relativistic quantum-information tasks.
Source: Classical and Quantum Gravity
Author: Tushar Waghmare
Institution: Indian Institute of Technology Kharagpur
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,325
OpenAlex ID: W7164839400