this post was submitted on 28 Mar 2025
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[–] Markuso213@lemmy.ml 3 points 1 day ago

There are still massive hurdles for using optical fibre networks for quantum information transmission. The biggest lies in attenuation, where information is lost as the optical signal traverses the fibre. This is an exponential decay, so the signal is lost very quickly for longer distances. This is also the case for normal fibre communication, but these signals can be amplified using conventional amplifiers (aka repeaters in some fields), which are conveniently placed every 80 km or so in order to boost the signal. In contrast, quantum states can not be amplified in a similar manner and have to rely on quantum repeaters which, well, are more of a theoretical concept at this point in time.

So, while the specialized equipment you refer to is indeed needed at both ends, the real challenge still lies in the quantum repeaters. Fortunately, satellite based communication is not as heavily punished by attenuation and would require fewer repeating steps (as compared to fibres) to transmit a quantum state from one end of the globe to the other. A handful of few repetition steps is a lot less daunting then the several hundreds that would be required for globe-scale quantum transmissions via fibre.