Question: what is the most apllicable use of quantum physics to technology and life today? Besides the quantum computer what could it be used for?

David Freeborn answered on 20 Jun 2013:

Hi harryphillips4,

We already use quantum physics in a lot of technologies! In fact, the computer you wrote this message on would not be possible without quantum mechanics!

All modern computers (since the 1940s) have been made from a series of electronic switches called transistors, made from semiconductor devices. A semiconductor is able to make a switch because we can make semiconductor devices that allow electrons to flow one way but not the other. This property is due to the quantum structure of the material, and it was only quantum mechanics that allowed us to develop these technologies.

Another quantum device that you use every day is lasers. Lasers are only possible because quantum particles sit in fixed energy levels. Coherent laser light is made when particles fall from a higher to a lower energy level. And we use lasers for a lot of things, from barcode scanners, to DVD readers, to precision laser-cutting devices.

Another big use of quantum physics is nuclear energy. Nuclear energy is the energy released by fusing atomic nuclei together. This would be impossible without our quantum theory of atomic nuclei. In the future, perhaps a few decades away, scientists hope to be able to use a process called nuclear fusion to generate almost limitless amounts of clean energy. All we need for nuclear fusion is hydrogen: one of the most common elements in the world, and we can get it easily from water. The only byproduct would be helium: a harmless gas. Nuclear fusion would solve all of the world’s energy needs, producing no pollution.

There are a lot of future Quantum Technologies that are now on the horizon! One of the most exciting will be Quantum cryptography. Because quantum systems are changed by the act of observation, quantum cryptography should be “impossible” to intercept and decode. When they intercept the encoded message, the “key” to the quantum code will be changed by the act of observation. That could allow much more security when transferring data than we have right now.

Another technology might be a new form of cancer detection. Scientists have discovered that some tiny semiconductor crystals called quantum dots glow when exposed to ultraviolet radiation and photographed. They then coat the quantum dots with a material that is attractive to cancer cells. When injected into the body, the coated glowing quantum dots latch on to cancer cells, showing doctors exactly where to look for the cells.

It’s also worth saying, we don’t know what other technologies lie ahead in the future! That’s one of the exciting things: new physics opens up new technologies that we can’t even dream about now!