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Numerous errors in the recent podcast about quantum computing

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The latest podcast (see the blog post about it, along with the comments under it pointing out mistakes) discusses quantum computing and what they call the "quantum internet". It makes a number of serious mistakes:

  • Quantum entanglement does not imply faster-than-light communications. Quite the opposite, as creating entangled states requires the transmission of actual particles, which cannot move faster than light. There is no latency advantage to using any quantum technique to transmit data.

  • Quantum key distribution still requires sending particles. They don't teleport. And they can be intercepted, but not without alerting both parties that interception has occurred.

  • Quantum computers are not supercomputers - they are only faster at solving very specific types of problems, like those in the BQP (Bounded-error Quantum Polynomial time) complexity class. The vast, vast majority of what a quantum computer can do is irrelevant to most people.

  • A read of a qubit is not simply a destructive read like that of a DRAM cell which must be corrected by re-writing the read value. It is called quantum decoherence and it acts on all entangled qubits, so the read must only be done at the very, very end of the computation (although a model called MBQC allows taking measurements during computation).

  • Google's claims of quantum supremacy are hotly contested due to the contrived nature of the problems they claimed to solve. Only quantum computers with full entanglement between each and every qubit (or nearest-neighbor "fuzzy" entanglement) really matter.


This segment of the podcast should either be retracted, or an erratum correcting the mistakes should be published. There are a lot of errors and I can't think of how to rectify them without redoing the entire podcast (which is, of course, impractical).


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