Editor's Choice

Demystifying quantum

30 April 2024 Editor's Choice

Recently, you have probably seen the word ‘quantum’ used everywhere – in computing, in names for tech companies, and maybe even for explanations of love and consciousness.

So, what is quantum? What is quantum technology? And is it worth all the hype?

Quantum, often called quantum mechanics, deals with the granular and fuzzy nature of the universe, and the physical behaviour of its smallest particles.

The idea of physical granularity is like your TV image. If you zoom in on the image, you will see it is made of individual pixels. The quantum world is similar. If you zoom in on the details of matter, you will eventually see elementary units of matter and energy with their own unique characteristics.

In the physical world, matter is made up of atoms as building blocks. Atoms, in turn, are made up of electrons that surround a nucleus. Nuclear particles, such as protons and neutrons, are made up of quarks.

If you look at an individual pixel, you know nearly nothing about the larger image. However, pixels working together can create enormous complexity in colour, shape and even movement from just the pixels’ colours: red, blue, green and off. The same is true of the quantum building blocks in physics.

What does quantum taste like?

In fact, the properties of all matter are defined by quantum physics. This is because the physical forces in the atom that bind it together – including the quantum properties of the elementary particles inside the atom – determine the physical and electronic structure of individual atoms.

More specifically, how the electronic charge is distributed in the atom decides the atom’s electrical properties. The atom’s electronic properties determine how atoms bond to other atoms to create molecules.

Atoms with similar electronic properties are listed in the same column of the periodic table, which describes the chemistry of those elements. The electrical structure of molecules decides how molecules work and bond together to create more complex materials, such as metals, liquids, gases and organic compounds. This even includes … you. Yes, you are quantum!

So, when we experience materials – the way they feel, smell and look – their overall ‘bulk’ properties are determined by the physical structure of quantum’s elemental building blocks and their electrical properties. We are essentially tasting, seeing and feeling the electromagnetic fields of matter.

Where did quantum come from?

While you may hear a lot about it lately, quantum physics is not new. It was deeply explored and developed around the early 1900s. The quantum nature of our world was discovered when mathematical models of the day didn’t match physical observations.

Interestingly, photons, or particles of light, were discovered by scientists trying to understand the relative intensity of different colours emitted by the newly invented lightbulb. It was a practical discovery indeed.

Ultimately, scientists learned that physics on the scale of elementary particles – and in the finest scales of energy, space and time – had different features and behaviours than objects we interact with in our ordinary lives, such as baseballs or cars. As mentioned previously, the discovery was a granular universe with unexplored behaviours, such as superposition, entanglement and quantum.

It is this novel nature of quantum mechanics that technologists are trying to use to advance technology in computing, communication, sensing and cryptography.

Why is there so much hype?

While we’ve known about quantum mechanics for more than a century, quantum-related technology has progressed rapidly in recent years. Currently, a lot of money is being invested in quantum technologies.

In 2022, the US government committed $1,8 billion in funding for quantum research and development. Private investments in quantum technology in the US have been close to $5 billion in the past two years.

While that might seem like a lot of money, according to some reports, China has committed $15 billion, and the European Union has committed more than $7 billion.

A recent report by McKinsey reported a potential return on investment of $1,3 trillion by 2035.

There’s a lot at stake in developing quantum systems. In the future, we may see quantum technology:

• Improving computing speed and power.

• Creating perfectly secure communications systems through quantum cryptography.

• Improving measurement capabilities by networking quantum sensors, such as atomic clocks and magnetometers.

While the above capabilities lie somewhere in the future (some more distant than others), even though you might not know it, you interact with quantum technology daily.


Semiconductors are materials engineered to behave somewhere between metals (conductors) and glass (insulators). Because they can be made to induce electrons to move or block electrons from moving, these powerful materials are used across multiple modern-day technologies as fast electronic switches.

For example, computers and portable electronic devices can have up to trillions of semiconductors used for computation and data storage. Motion detectors, solar panels, LEDs in lightbulbs, and many lasers and sensors are based on semiconductors that convert light to electricity or vice versa. Semiconductors are so ubiquitous that the annual global market was close to $600 billion last year.

Motion detectors

Motion detectors, mentioned above, convert light reflected from a surface, like your clothes or body, to create an electrical signal that acts like a switch. This is a quantum phenomenon called the photoelectric effect, which won Albert Einstein a Nobel Prize. Motion detectors are used to open supermarket doors, turn on a light in your house or turn on a faucet in a public restroom. Yes, quantum is in your bathroom.


Lasers are so common in modern life that you can buy them for less than $10 to entertain your cat. They are used in construction to keep things level, in medicine for surgery, and to control TVs and video boxes remotely. People also use them for data storage or for skin resurfacing and hair removal.

Lasers work on the quantum principle of stimulated emission. In stimulated emission, all the emitted light has the same colour or ‘wavelength’. Mirrors in the laser make sure that the light comes out in the same direction.

In this case, the wavelengths of light emitted from a laser all add together, making a super-strong wave. In this wave, the peaks and valleys of the wave perfectly line up.

This is a little bit like when all instruments in an orchestra play the same note in unison, creating a powerful, resonant sound wave. When the light waves from a laser all add together, they create a directed and cooperative light source that can be used for laser machining and welding. This light power can also probe and study the electronic structure of materials, called spectroscopy, or can be used to travel massive distances in space.

Atomic clocks and GPS

Atomic clocks have been used to help standardise time internationally since 1967. These clocks use the atom’s electronic structure to create a highly regular timing signal by cycling electrons between two quantum energy levels. Because atomic clocks are so accurate and stable, they are central to ensuring accurate navigation in GPS. Using GPS, the internet and cellular towers, the clocks on portable electronics worldwide are synchronised with atomic clocks at NIST and other national labs. Amazingly, NIST uses its clocks to help synchronise 80% of portable electronics worldwide.

Where to from here?

Many of the above applications were developed during what many call the first quantum revolution. Generally speaking, these technologies take advantage of the collective electronic behaviour of atoms, material and light.

Some technologists believe we are entering the second quantum revolution, which will harness the more exotic nature of quantum mechanics, namely quantum entanglement.

Entanglement, superposition and correlated behaviour in quantum systems may allow a quantum computer to out-compute classical computers. Quantum systems may also create unbreakable codes for cryptography, which has concerning implications for cybersecurity. Luckily, researchers at NIST and elsewhere are working to develop post-quantum encryption that would be hard even for quantum computers to break.

On a more fun note, some of the behaviour of quantum mechanics will potentially create completely new opportunities that might reveal themselves as more people get creative, and become more involved in quantum technologies. No scientist in the 1960s thought the laser would be used for skin resurfacing or cat toys, but as participation diversifies, more novel and commercial applications begin to surface.

For more information visit www.nist.gov

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