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Quantum Wonders card QTM-45, Quantum Dots, with a glowing paper-cut illustration. It reads: Shrink certain crystals to a few nanometres across and their colour depends on their size.

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Quantum Dots

What’s going on

In a speck of semiconductor just a few nanometres wide, electrons are squeezed so tightly that their allowed energy steps spread apart. Smaller dots have bigger steps, so they glow bluer; larger dots glow redder, even when made of the very same material. Quantum dots colour some TV screens and can help surgeons see tumour tissue. Their discovery won the 2023 Nobel Prize in Chemistry.

Myth

A material’s colour depends only on what it is made of.

Fact

For quantum dots, size matters too.

Learn more

Nobel Prize in Chemistry 2023 (Bawendi, Brus, Ekimov), nobelprize.org.

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QTM-45 from Quantum Wonders, free quantum physics cards for ages 10 to adult

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