Horizons as eavesdroppers: decoherence from soft radiation

Abstract: Recently, Danielson, Satishchandran, and Wald proposed a novel mechanism for decoherence in spacetimes with Killing horizons. When Alice performs a Stern-Gerlach type experiment outside the horizon, there is a fundamental rate of decoherence due to the emission of soft gravitons/photons that radiate away information. In this talk, I will sharpen and generalize this mechanism by recasting the gedankenexperiment in the language of (approximate) quantum error correction. By explicitly computing the quantum fidelity between the vacuum state on the horizon and the state with soft radiation propagating through the horizon, we characterize how much an eavesdropper (Eve) behind the horizon is able to learn about Alice's experiment. From the information-disturbance tradeoff, there is a direct relation between the information gained by Eve and the decoherence of Alice's generalized experiment. I will comment on how an information-theoretic language may lead to new insights on energy/entropy inequalities, islands, and the central dogma of black holes.

HEP - theorymathematical physicsquantum physics

Audience: researchers in the topic

( video )

Purdue HET

Series comments: The recorded talks will be available on YouTube here: www.youtube.com/playlist?list=PLxU3vHZccQj64m9zsQR74D5WP1z1g4t1J