The influence of the Earth’s curved spacetime on Gaussian quantum coherence

Abstract

Light wave-packets propagating from the Earth to satellites will be deformed by the curved background spacetime of the Earth, thus influencing the quantum state of light. We show that Gaussian coherence of photon pairs, which are initially prepared in a two-mode squeezed state, is affected by the curved spacetime background of the Earth. We demonstrate that quantum coherence of the state increases for a specific range of height h and then gradually approaches a finite value with further increasing height of the satellite's orbit in Kerr spacetime, because special relativistic effect are involved. Meanwhile, we find that Gaussian coherence increases with the increase of Gaussian bandwidth parameter, but the Gaussian coherence decreases with the growth of the peak frequency. In addition, we also find that total gravitational frequency shift causes changes of Gaussian coherence less than %1 and different initial peak frequencies also can effect rate of change with the satellite height in geostationary Earth orbits.

Characterization of quantum and classical correlations in the Earth’s curved space-time

“…However, one could also perceive that the quantum discord is more sensitive to the change of frequency parameter B than the classical correlation. Finally, in the framework of a quantity describing the change rate of three types of correlations, we detect a special (16) www.nature.com/scientificreports/ height ( h = 2r A ) at which the blueshift and redshift effects are offset. More importantly, the changes of correlations generated by the total gravitational frequency shift is determined at the level of < 0.5% within the satellite's height at geostationary Earth orbits.…”

“…For instance, it was found in 14 that there would be inevitable losses of quantum resources in the estimation of the Schwarzschild radius. Furthermore, a quantitative investigation of the dynamics of satellite-based quantum steering and coherence has been presented in 15,16 , given the curved background space-time of the Earth. Nowadays, it is possible to explore those quantum correlations with quantum discord acting as a resource in quantum protocols, as well as the correlations related to the practical implementation of many quantum information schemes in relativistic quantum systems, such as, quantum key distribution through satellite nodes 17 and other quantum information tasks [18][19][20][21][22][23] .…”

Advances in Space Quantum Communications

“…Satellites can also be used to probe other effects associated with entanglement. For instance, it has been shown that the entanglement of Gaussian states [405,406], two mode-squeezed states [408] and multipartite W-states [409] show measurable changes in curved spacetime. Additionally, curved spacetime has been theorised to create entanglement [410].…”

Characterization of quantum and classical correlations in the Earth curved space-time

“…For instance, it was found in 14 that there would be inevitable losses of quantum resources in the estimation of the Schwarzschild radius. Furthermore, a quantitative investigation of the dynamics of satellite-based quantum steering and coherence has been presented in 15,16 , given the curved background space-time of the Earth. Nowadays, it is possible to explore those quantum correlations (with quantum discord acting as resources in quantum protocol) and the correlations in relativistic quantum systems (which is related to the practical implementation of many quantum information schemes, i.e., quantum key distribution through satellite nodes 17 and other quantum information tasks [18][19][20][21][22][23] ).…”