A communications network secured by the laws of quantum physics would be unhackable, but building one requires a component called a quantum memory, which is still being developed
Source:
https://www.newscientist.com/article/2233317-record-breaking-quantum-memory-brings-quantum-internet-one-step-closer/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home