Killing Horizons Decohere Quantum Superpositions

Abstract

We recently showed that if a massive (or charged) body is put in a quantum spatial superposition, the mere presence of a black hole in its vicinity will eventually decohere the superposition. In this paper we show that, more generally, decoherence of stationary superpositions will occur in any spacetime with a Killing horizon. This occurs because, in effect, the long-range field of the body is registered on the Killing horizon which, we show, necessitates a flux of "soft horizon gravitons/photons" through the horizon. The Killing horizon thereby harvests "which path" information of quantum superpositions and will decohere any quantum superposition in a finite time. It is particularly instructive to analyze the case of a uniformly accelerating body in a quantum superposition in flat spacetime. As we show, from the Rindler perspective the superposition is decohered by "soft gravitons/photons" that propagate through the Rindler horizon with negligible (Rindler) energy. We show that this decoherence effect is distinct from--and larger than--the decoherence resulting from the presence of Unruh radiation. We further show that from the inertial perspective, the decoherence is due to the radiation of high frequency (inertial) gravitons/photons to null infinity. (The notion of gravitons/photons that propagate through the Rindler horizon is the same notion as that of gravitons/photons that propagate to null infinity.) We also analyze the decoherence of a spatial superposition due to the presence of a cosmological horizon in de Sitter spacetime. We provide estimates of the decoherence time for such quantum superpositions in both the Rindler and cosmological cases. Although we explicitly treat the case of spacetime dimension $d=4$, our analysis applies to any dimension $d\ge 4$.

16 pages, 1 figure. Accepted for publication in Phys. Rev. D. v2: Added clarifying remarks and a figure, and pointed out that the effect arises for any d>=4; corrected equation (3.18)

References in corpus (7)

• A Spin Entanglement Witness for Quantum Gravity
• Gravitationally-induced entanglement between two massive particles is sufficient evidence of quantum effects in gravity
• The Asymptotic Behavior of Massless Fields and the Memory Effect
• Infrared quantum information
• Dressed infrared quantum information
• Hadamard States From Light-like Hypersurfaces
• The electric field of a charge in the vicinity of a higher dimensional black hole

Cited by in corpus (25)

• In-in formalism for the entropy of quantum fields in curved spacetimes
• Decoherence by warm horizons
• Local Description of Decoherence of Quantum Superpositions by Black Holes and Other Bodies
• An Open Effective Field Theory for light in a medium
• Does decoherence violate decoupling?
• Infrared finite scattering theory: Scattering states and representations of the BMS group
• Infrared finite scattering theory: Amplitudes and soft theorems
• Entanglement Harvesting and Quantum Discord of Alpha Vacua in de Sitter Space
• The Role of Quantum Measurements when Testing the Quantum Nature of Gravity
• How to Minimize the Decoherence Caused by Black Holes
• Circuit locality from relativistic locality in scalar field mediated entanglement
• Decoherence of spin superposition state caused by a quantum electromagnetic field
• Energy change and Landauer's principle in the interaction between qubit and quantum field theory
• Gravity induced entanglement of multiple massive particles with large spin
• Horizon quantum geometries and decoherence
• Null infinity as a Killing horizon
• Effects of quantum geometry on the decoherence induced by black holes
• Can Newtonian Gravity Produce Quantum Entanglement?
• Using thermodynamics to learn gravitational wave physics
• Unveiling quantum complementarity tradeoffs in relativistic scenarios
• Hawking radiation for detectors in superposition of locations outside a black hole
• On the nature of the black hole information problem
• Lectures on the Bondi--Metzner--Sachs group and related topics in infrared physics
• Gravitational waves decohere quantum superpositions
• Generalized Eddington--Finkelstein Coordinates and Exact Vaidya-Type Solutions in Weyl Conformal Gravity