Scholars Mind

Quantum Computing and Q-Day

Who wouldn’t want quantum supremacy? In 2019, Google made a splashy headline: they’d achieved it! Others soon claimed they had too. But researchers admit quantum computers still have no practical purpose, even as cryptographers worry that they could someday be used to hack even the most encrypted passwords. Read more about this much-dreaded Q-Day, then discuss with your team: should we be developing technologies that have unclear practical advantages but clear downsides?

Key concepts

Qubit
A quantum bit, which unlike an ordinary bit can hold a blend of 0 and 1 at once. Add qubits and the states they can represent together multiply rather than add — but that blend is so fragile that the machines need near-absolute-zero cooling and still fail about once in a thousand operations. That fragility is the gap between winning one benchmark and doing useful work.

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Every work — at a glance

  • Quantum Supremacy — Google (milestone)

    Google's 2019 claim that its 54-qubit chip beat a supercomputer at a task chosen to be hard, not useful.

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What to know

  1. 01
    Beating a supercomputer and being useful are separate achievements, and only one has happened. Google's chip won at a contrived benchmark; researchers still concede the machines have no practical purpose, while billions keep arriving. So the honest reading of the headline is a speed record on a made-up race, not a new tool anybody can use yet.

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Across subjects

History already ran this experiment. In January 1917 Britain's Room 40 decoded a German telegram offering Mexico American territory for an alliance; publishing

Theme connection

"Are We There Yet?"

Should anyone build a technology whose dangers are clear and whose uses are not? One case: foundational research always looks pointless first, and standing aside just hands the machine to someone less careful. The other: 'somebody else would' is an excuse rather than a reason, and this is the first doomsday with a budget and a launch date.

Practice — a sample

SCIThe 2008 collider lawsuits argued over unsettled physics. The key difference is that the Q-Day warning rests on a settled —

  • A Proof
  • B Law
  • C Measurement
  • D Estimate
  • E Precedent

Sign in to answer and see why each option is right or wrong.

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