Spinning black holes are capable of complex quantum information processes encoded in the X-ray photons emitted by the accretion disk.
The black holes sparked the public imagination for almost 100 years now. Their debated presence in the universe has been proven without a doubt by detecting the X-ray radiation coming from the center of the galaxies, a feature of massive black holes. Black holes emit X-ray radiation, light with high energy, due to the extreme gravity in their vicinity. The vast majority if not all of the known black holes were unveiled by detecting the X-ray radiation emitted by the stellar material accreting around black holes.
X-ray photons emitted near rotating black holes not only exposed the existence of these phantom-like astrophysical bodies, but also seem to carry hidden quantum messages.
A recent paper posted in the pre-printed archive arXiv (Photonic Bell states creation around rotating black holes - http://arxiv.org/abs/1608.06822 argues that X-ray radiation coming from faster spinning black holes encompasses quantum information. Quantum information is encoded in the degrees of freedom X-ray photons acquire during their journey throughout the warped and twisted space-time near the rotating black hole.
Space-time possesses a very particular shape near spinning black holes. It is curved and twisted. The curvature of the space-time rotates the polarization angle of photons emitted or passing near black hole. The twist of space-time imprints orbital angular momentum to photons. These two degrees of freedom acquired by the photons encode quantum information processes. It can implement quantum gates and quantum circuits like Bell states.
Bell states measure the degree of entanglement in the X-ray photons and are strongly related to the spinning speed of the black holes. It is argued in the recent paper that the faster black hole spins the louder and clearer the quantum message black hole is sending to the vast Universe.
In the program Quantum Experiments at Space Scale (QUESS), recently China launches the first quantum communication satellite designed to connect us to a future global quantum information network. This endeavor raises the hope that recent future will bring us closer to connect to the Universe quantum information network.
We argue that spinning black holes are capable to implement complex quantum information processes encoded in X-ray photons emitted by the accretion disk. Recently, numerical simulations showed that X-ray photons emitted by accretion disk acquire rotation of polarization angle and orbital angular momentum due to strong gravitational field in the vicinity of the rotating black holes. Based on these two degrees of freedom we construct a bipartite two-level quantum system of the photons emitted by the accretion disk. To characterize the quantum states of this system we consider linear entropy for the reduced density matrix of polarization with the intention to exploit its direct relation with the photons degree of polarization. Since the X-ray radiation has a minimum degree of polarization located at the transition region of the accretion disk, the linear entropy is higher for the photons emitted on this region inferring a higher degree of entanglement for the composite system. We emphasize that for an extreme rotating black hole in the thermal state, the photons with energies at the thermal peak are maximally entangled in polarization and orbital angular momentum, leading to the creation of all four Bell states. Detection of the Bell states encoded by X-ray photons emitted nearby rotating black holes should be possible by equipment actually used in quantum information processing.