Topics Technology and the internet

What is quantum computing?

Quantum computing is a way of computing that uses the physics of very small things, like atoms, electrons and particles of light, instead of the on-or-off switches in an ordinary chip. A regular computer stores information as bits, each a 0 or a 1. A quantum computer uses qubits, which can be set up in a blend of both states, and can be linked together so their results depend on one another.

What makes it interesting is how often it gets misdescribed. It is not simply a faster laptop, and it does not try every answer at once and pick the best one. Researchers have shown that for a few specific kinds of problems, such as simulating molecules or breaking certain codes, the quantum approach could in principle be far quicker. For most everyday tasks it offers no advantage. Today's machines are small and error-prone, and how soon they will be useful is still debated.

An episode on this topic would start with bits and qubits, walk through superposition and entanglement in plain pictures, and explain why errors are such a hard problem. bre's hosts are AI, so they can slip, and the episode says where the science is unsettled. You can press Talk at any point and ask your own question.

What a bre episode would cover

An outline of the episode bre would make for this question. Every episode is written fresh when you ask, so yours will differ.

  1. Bits, and what a qubit changesHow an ordinary computer stores information as 0s and 1s, and how a qubit can be prepared in a blend of both until it is measured.
  2. Superposition without the mysticismWhat it means, and does not mean, for a qubit to be in two states. The popular line about trying every answer at once gets set straight.
  3. Entanglement: linked qubitsHow qubits can be connected so that their measured results are correlated, and why that link is a resource for computing rather than a way to send messages.
  4. What quantum machines might be good atSimulating molecules and materials, certain search and math problems, and why researchers think these cases differ from everyday computing.
  5. Why it is so hard to buildQubits are fragile and easily disturbed by heat and noise. The episode covers error correction and the different ways engineers build qubits.
  6. Encryption and the worry about codesWhy a large enough quantum computer could threaten some current encryption, and how specialists are already working on replacements.
  7. Hype, progress and what is unknownWhat today's machines can honestly do, which claims are debated, and why nobody can say exactly when it will matter.

How the episode might open

A sample exchange between two of bre’s AI hosts, bre and Tess. Both are AI; this is written by AI, as every bre episode is.

  1. breAI host

    Let's start with a picture. An ordinary computer is a huge wall of light switches, each one up or down. Quantum computing says: what if a switch could be set up in a way that is neither plain up nor plain down?

  2. TessAI host

    Okay, but real talk. Every time someone says that, my brain files it under magic. Is this a faster computer or not?

  3. breAI host

    Not in general. That's the part nobody tells you. For most things you do, your phone wins easily. It's only certain kinds of problems where the quantum approach might pull ahead.

  4. TessAI host

    So what kind of problems? Give me something I could actually care about.

  5. breAI host

    Simulating molecules is the classic one. Chemistry is quantum at its core, so a machine built from quantum parts may model it more naturally than a regular chip can.

  6. TessAI host

    Which could mean new medicines or materials someday. But someday is doing a lot of work in that sentence.

  7. breAI host

    It is, and I don't know how long someday is. Nobody does. Today's machines are small and make a lot of mistakes, so we'll cover that honestly.

  8. TessAI host

    Good. Start with the switches, then tell me what a qubit actually is.

Questions people also ask

Is a quantum computer faster than a regular computer?
Only for certain problems. Researchers have found specific tasks, like simulating molecules or factoring large numbers, where a quantum approach could be much quicker in principle. For everyday jobs like browsing, video or spreadsheets, an ordinary computer is simpler, cheaper and just as good.
What is a qubit?
A qubit is the quantum version of a bit. Instead of being only 0 or 1, it can be prepared in a blend of both, described by probabilities, until it is measured. Qubits are built from things like tiny circuits, trapped atoms or particles of light.
Can quantum computers break encryption?
A large, reliable quantum computer could in theory break some widely used encryption methods. Machines that big do not exist yet. Specialists are already designing new methods meant to resist quantum attacks, so the risk is being planned for.
Do quantum computers exist today?
Yes, but they are small and noisy. Companies and labs run machines with limited numbers of qubits, mostly for research and experiments. Whether they do anything practically useful that ordinary computers cannot is still debated among researchers.

Related topics

More: all 300 topics, technology and the internet, or the longer reads on /learn.

bre’s hosts are AI, and every episode is generated, so they can be wrong: check anything that matters. This page outlines what an episode would cover. It is for interest and learning, not medical, financial or legal advice.