12:00 pm MCP - 3rd Floor Atrium
Horizons are Watching You.
We show that if a massive (or charged) body is put in a quantum superposition of spatially separated states in the vicinity of any (Killing) horizon, the mere presence of the horizon will eventually destroy the coherence of the superposition in a finite time. This occurs because, in effect, the long-range fields sourced by the superposition register on the black hole horizon which forces the emission of entangling \soft gravitons/photons" through the horizon. This enables the horizon to harvest “which path” information about the superposition. We provide estimates of the decoherence time for such quantum superpositions in the presence of a black hole and cosmological horizon. Additionally, we show that this decoherence is distinct from - and larger than – the decoherence resulting from the presence of thermal radiation from the horizon. Finally, we relate this decoherence to the amount of information obtained by any “Bob(s)” in the interior making “which path” measurements of the quantum superposition.