Quantum Entanglement for Remote Sensing? Options

[algorimancer]

This may be a bit of a far-out notion, but perhaps not. I've been seeing a lot of work on quantum entanglement showing up in various journals lately, commonly with the intent of secure communications or computation. Quantum mechanics is not my realm of expertise, but I wonder whether this might be employed as a remote sensing mechanism. Entanglement can be established between subatomic particles and/or photons, so I might envision entangling a photon with a particle (actually swarms of such pairs), then projecting the entangled photon towards some astronomical object of interest - perhaps towards an asteroid or comet or satellite or planet in our solar system, but conceivably towards another star. When the projected photon interacts with the distant target this interaction would be detected by observing the change in the paired particle retained in the transmitter, and interpretation would be something like performing spectroscopy (assuming multiple entangled states) or radar (single state) on the target object. By tracking time and direction of the transmitted photons this would even provide a remote imaging modality for targets which are otherwise too faint to detect telescopically. The same system if used to entangle particles with neutrinos would allow probing the interiors of the Earth and Sun - perhaps even other planets.

One obvious limitation with this notion is the length of time the entanglement can be maintained, which I think so far has been limited to a few seconds or minutes, so that near-term this technique would be of most use on the Moon and near-earth asteroids, but perhaps Mars & Venus as well. Progress seems to be continuing, so perhaps in a few years entanglements which last hours or even years may be feasible. Another limitation may be that interaction of the transmitted photons with the atmosphere may restrict this to a space-based activity, otherwise existing telescopes might be used as transmitters.