NederlandsQuantum computer
A quantum computer calculates with qubits, which can be in several states at once. That lets it solve some problems much faster than an ordinary computer.
A quantum computer is a computer that calculates using the rules of quantum physics. An ordinary computer uses bits, which are either a 0 or a 1. A quantum computer uses qubits, which can be in both states at once. For some kinds of problems that brings an enormous speed-up. A quantum computer is not a faster version of an ordinary computer for everything: it is mainly meant for specific tasks.
How does it work?
A quantum computer consists of qubits, such as superconducting loops, charged atoms or electrons in silicon, plus equipment to operate and read them. They often have to be cooled to just above absolute zero, or held in place in a vacuum with lasers. A program makes the qubits act on one another step by step, and at the end you measure the result.
The biggest challenge is that qubits are fragile. A little heat or a vibration is enough to disturb them. That is why researchers are working on quantum error correction, in which many qubits together form one reliable qubit.
Why it matters
Quantum computers can calculate molecules and materials that are too complicated for ordinary computers, for example for new medicines and batteries. On Quantinuum's Helios computer, something went wrong on average only five times in a million per check round, ten times better than the previous record (link). IBM connected two quantum chips of 120 qubits each with four superconducting links of 80 centimetres, a step towards quantum computers built from separate modules (link). Another report concerns what such a machine might one day break: the French company Alice & Bob calculates that a quantum computer with some 23,000 qubits could crack the widely used RSA encryption in just over three days, far fewer qubits than previously thought (link). Such a machine does not exist yet.
Articles about Quantum computer
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Stanford builds a grid of more than 600 light traps to link quantum computers made of atoms
Physicists at Stanford built a grid of more than 600 tiny light traps, each of which can catch the light of a single atom. That helps to read out quantum computers made of atoms faster and later to link them together.
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Oxford keeps a quantum link between atoms in two places alive for more than ten seconds
Physicists at the University of Oxford linked atoms of strontium and calcium in two places into a single quantum state. By passing the link on to calcium, it lasted more than ten seconds instead of milliseconds. A step towards networks of quantum computers.
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Electron pairs survive after superconductivity is gone
Physicists saw that electrons in a metal keep forming pairs even when it is just too warm for superconductivity. That helps to understand how electricity without losses comes about. The next step is to see whether it also happens inside the material.
