From qubits to black holes: entropy, entanglement and all that

TL;DR

This paper explores the role of entropy and entanglement in black holes, highlighting how quantum gravity predicts entropy corrections and how entanglement may restore unitarity in black hole evaporation.

Contribution

It connects entropy, entanglement, and quantum gravity predictions, proposing that matter-gravity entanglement explains Hawking radiation entropy.

Findings

Logarithmic correction to black hole entropy from spin network entanglement

Entanglement between gravity and matter may restore unitarity

Hawking radiation entropy equals matter-gravity entanglement for pure initial states

Abstract

Entropy plays a crucial role in characterization of information and entanglement, but it is not a scalar quantity and for many systems it is different for different relativistic observers. Loop quantum gravity predicts the Bekenstein-Hawking term for black hole entropy and logarithmic correction to it. The latter originates in the entanglement between the pieces of spin networks that describe black hole horizon. Entanglement between gravity and matter may restore the unitarity in the black hole evaporation process. If the collapsing matter is assumed to be initially in a pure state, then entropy of the Hawking radiation is exactly the created entanglement between matter and gravity.