Some calculations done by scientists at the University of Edinburgh in the UK indicate the possibility that quantum signals could be used to establish communication over vast distances, which implies that our technology may need to be updated in order for us to be aware of such signals if they come our way.
This conclusion may come as a surprise, considering the difficulty of establishing quantum linkages on Earth. Individual nodes in these networks are linked by the creation and transmission of quantum states, but these states are unstable, and their propensity to decohere (i.e. lose their quantum character) limits the stability of these linkages. Interstellar connections, therefore, offer a significant step forward in space exploration. In order to reach an interstellar receiver, could quantum information withstand the harsh conditions of space?
Researchers in Edinburgh attempted to address this issue by calculating the possible effects of different perturbations on a quantum signal. Gravity is one such perturbation that might lead to the decoherence of quantum states and the degradation of signal quality. A photon may travel up to 127 light-years before becoming decoherent, which means that a large number of stars with confirmed exoplanets are all within our range.
Since decoherence is not the only factor that affects a quantum signal’s integrity or quality, traveling over space has a somewhat different effect. The term “high fidelity” refers to the ability to completely process a received quantum signal. Wigner rotation is a relativistic phenomenon that may alter the signal’s phase, resulting in a decrease in fidelity while maintaining coherence. It’s possible, however, to estimate this effect’s amplitude and compute the signal’s original phase if receivers know the signal’s source information.
A photon’s quantum state may be disrupted by a number of different forces than gravity. Electrons, photons, hydrogen atoms, and a few heavier elements may be found in interstellar space. Our own Sun may likewise be a source of these particles. In fact, no significant interaction can be predicted when the researchers estimated the chance of a signal photon engaging with any of them, since the mean free path range was greater than the visible universe. They have longer mean free routes through scattering and absorption substances such as gas and dust and are less vulnerable to interference from strong magnetic fields. This makes X-ray wavelengths ideal for quantum communication.
Could aliens prefer this communication?
An alien culture could prefer quantum communication over conventional communications, the researchers hypothesized. As Arjun Berera, a professor at Edinburgh and the main author of the study, points out, there are some advantages to the research. A possible explanation is that the quantum character of the signal indicates that it is the product of intelligent design rather than the result of a random process. When using higher-dimensional entangled states, quantum communication makes it feasible to cram a lot more information into the signals.
