# Quantum gates implementation by X-ray single-photons around rotating black holes

## TL;DR

This paper explores how the curved spacetime around rotating black holes can implement quantum gates and circuits using photons' polarization and orbital angular momentum, suggesting a novel astrophysical quantum information processing method.

## Contribution

It demonstrates that spacetime effects near rotating black holes can be used to realize elementary quantum gates and circuits with emitted photons, bridging astrophysics and quantum information.

## Key findings

- Implementation of Hadamard and C-NOT gates using black hole spacetime effects
- Generation of Bell states from photons emitted near black holes
- Potential for quantum information detection in astrophysical environments

## Abstract

The curvature and twisting of spacetime rotate the angle of polarization and imprint orbital angular momentum to photons emitted by the accretion disk near rotating black holes. Considering polarization and orbital angular momentum as two degrees of freedom of single-photons that can encode quantum information, we emphasize that the particular shape of spacetime around rotating black holes implements quantum gates and simple quantum circuits. Consequently, we demonstrate the implementation of some elementary quantum gates, like Hadamard or C-NOT, and simple quantum circuits, like Bell states, with photons in the presence of spinning black holes. Detection and measurement of quantum information encoded in photons emitted in the accretion disk around rotating black holes may be performed by actual quantum information technology.