A curious observer’s guide to quantum mechanics, PT 7: Quantum Century

The future is already here – it’s not very evenly shared –William Gibson

As tool builders, it is only recently that we have been able to use quantum mechanics. Understanding and manipulating quantum devices has been like getting drugs into a new superpower – there are so many things we can create now that would have been impossible a few years ago.

We have encountered some such quantum techniques in previous articles. Some of them, like quantum dots in TV, are already becoming commonplace; Others, like optical clocks, exist but are still very rare.

Since this is the last article in this series, I look forward to the near future where quantum technologies are likely to affect our everyday existence. No one needs to look further – all the technologies we will find today already exist. Most of them are still rare, isolated in laboratories or as technology demonstrators. Others are hidden from plain sight, such as an MRI machine at a local hospital or a hard drive sitting at your desk. In this article, let’s focus on some technologies we didn’t encounter in previous articles: superconductivity, micro-polarization, and quantum electronics.

As we look at these quantum technologies, imagine what it would be like to live in a world where quantum devices are everywhere. What does it mean to be technically literate when quantum mechanics is a prerequisite for understanding everyday technology?

So choose your binoculars, and let’s look at the quantum technologies coming to the forefront.

Superconductors

In a normal conductive wire, you can attach a battery and measure how fast an electron moves through it (current, or number and speed of the electron). It takes a little pressure (voltage) to move the electron forward, and releasing it releases a little heat – think of the red glow of the coil in a room heater or hair dryer. The difficulty is to push the electron through the material Resistance.

But we know that electrons move as waves. As you cool all the atoms in the material, the size of the electron waves carrying the electric current increases. Once the temperature is low enough, this annoying electron can pass through being an annoying subtlety to the defined characteristic. Suddenly electron waves join and move easily through the material – the resistance comes to zero.

The temperature at which the torment of an electron increases depends on the crystal the electron arrives from, but it is always cold, which is the temperature at which a gas like nitrogen or helium becomes liquid. Despite the challenge of keeping things in this cool, superconductivity is a beautiful and useful asset that we will use anyway.

Electromagnet. The most widespread use of superconductivity is for electromagnets in MRI (magnetic resonance imaging) machines. As a child, you would have created an electro-magnet by attaching a wire around a nail and attaching a wire to a battery. The magnet of the MRI machine is similar, it has only one large coil of wire. But when you have of 1000 amps flowing through the wire, the magnet stays working Expensive. It will generally look like the largest space heater in the world.

So the answer is to use special wire and cool it in liquid helium. Once it is superconducting, you can plug it into a power source and apply current (this takes 2-3 days – this is a great video of plugging in an MRI magnet). Then you unplug the magnet and Walk away. Since there is no resistance, the flow will continue as long as you keep the magnet cool. When a hospital installs a new MRI, the magnet is turned on when installed, then unplugged and left for the rest of life.

While MRI machines are the most visible examples, superconducting magnets are actually quite common. Any good chemistry laboratory or department will have many superconducting magnets in their nuclear magnetic resonance (NMR) machines and mass spectrometers. The Super Hendron Collider is a line of 18 km of superconducting magnets and they show up differently in the physics section. When we had the Schustring project, I put a superconducting magnet from the storage alley behind my lab and renewed it. Physicists mail glossy catalogs to magnet manufacturers by superconducting.

Transmission lines. The next obvious application is to use it to conduct electricity by pulling a superconducting wire. There are many demonstration projects around the world that use superconducting power lines. Like most industrial applications, it is a matter of finding cases where a superconductor’s performance is worth its high price. As prices come down, long-distance superconducting transmission lines could be crucial as we add more renewable solar and wind energy to the grid – even local variations in renewable power generation due to being able to carry power long distances for free.

Generators and motors. If you have an incredibly strong superconducting magnet, you may want to use it in electric generators and motors. Cooling, as always, is an issue, but stronger magnets can make motors / generators significantly smaller and more efficient. This is especially attractive for wind turbines (weight loss on towers), and electric drives for boats and aircraft (low weight and improved efficiency).