Curator's Take
This theoretical work tackles a fundamental question in quantum mechanics: how does motion through spacetime itself cause quantum superpositions to decohere? The researchers demonstrate that particles following curved trajectories through flat spacetime experience decoherence through two distinct relativistic mechanisms - modified field interactions and differential time dilation across the particle's wavefunction - both of which manifest as thermal-like noise. This represents an important step toward understanding how gravity and acceleration might fundamentally limit quantum coherence, with potential implications for precision quantum sensors operating in varying gravitational fields and future tests of quantum mechanics in curved spacetime. The work bridges quantum field theory and quantum information science, providing a rigorous framework for calculating decoherence rates in relativistic settings that could inform the design of space-based quantum technologies.
— Mark Eatherly
Summary
We analyze the decoherence of a particle's spatial superposition moving along a stationary worldline through the Minkowski vacuum. The particle is modeled via an internal degree of freedom that couples to a scalar field, and an external degree of freedom, i.e., its quantized center-of-mass motion around the stationary worldline. Assuming a separation of time scales between the particle's internal and external dynamics, we first obtain an effective red-shifted polarizability of the particle, characterizing the trajectory-dependent linear response of the internal oscillator to the field. We then derive a quantum Brownian motion master equation for the particle's center of mass, under the Born-Markov approximation, which describes its decoherence in the position basis, as well as, Hamiltonian modifications corresponding to a dispersive potential. The resulting decoherence has two components: (1) arising from a modified field spectrum observed by the particle; and (2) due to a differential time-dilation over the particle's extended spatial wavefunction. For stationary trajectories, both contributions take an effectively thermal form. We evaluate the decoherence rates for two specific cases of hyperbolic and uniform circular motion.