Coherence

Clear as Quantum

John Bartholomew talks about quantum memories and the challenges of keeping quantum information "coherent".

John explores the limit of how long quantum information can be stored - a "quantum memory" is an important part of quantum information technologies. He was part of a team that set the record for this "coherence time" of about 6 hours (using super-cold glowing crystals). This might seem short compared to classical hard drives, but its excitingly long enough to imagine building a quantum sneaker-net. In fact this idea of coherence gets at the boundary between quantum and classical! John shares his own journey from a small country town to a commute within view of the Eiffel Tower in Paris, and the super-fridges from Episode 1 make a reappearance.

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