In the future, everyone might use quantum computers

In the future, everyone might use quantum computers
Programming in BASIC. Credit: David Firth/Wikimedia

Computers were once considered high-end technology, only accessible to scientists and trained professionals. But there was a seismic shift in the history of computing during the second half of the 1970s. It wasn't just that machines became much smaller and more powerful—though, of course, they did. It was the shift in who would use computers and where: They became available to everyone to use in their own home.

Today, quantum computing is in its infancy. Quantum computation incorporates some of the most mind-bending concepts from 20th-century physics. In the U.S., Google, IBM and NASA are experimenting and building the first quantum computers. China is also investing heavily in quantum technology.

As the author of "Quantum Computing for Everyone," due out in March, I believe that there will be an analogous shift toward quantum computing, where enthusiasts will be able to play with quantum computers from their homes. This shift will occur much sooner than most people realize.

Rise of personal computers

The first modern computers were constructed in the 1950s. They were large, often unreliable, and by today's standards, not particularly powerful. They were designed for solving large problems, such as developing the first hydrogen bomb. There was general consensus that this was the sort of thing that computers were good for and that the world would not need many of them.

Of course, this view turned out to be completely wrong.

In 1964, John Kemeny and Thomas Kurtz wrote the BASIC language. Their goal was to design a simple programming language that would be easy to learn and would enable anyone to program. As a result, programming was no longer solely for highly trained scientists. Anyone could now learn to program if they wanted to.

This shift in computing continued when the first home computers appeared in the late 1970s. Hobbyists could now buy their own computer and program it at home. Parents and children could learn together. These first computers were not very powerful and there were a limited number of things that you could do with them, but they had an extremely enthusiastic reception.

As people played with their machines, they realized that they wanted more features and more power. The founders of Microsoft and Apple understood that the home computer had a bright future.

Almost every American now owns a laptop, tablet or smartphone – or all three. They spend a lot of time on social media, e-commerce and searching the internet.

None of these activities existed in the 1950s. Nobody at the time knew that they wanted or needed them. It was the availability of a new tool, the computer, that led to their development.

Enter quantum

Classical computation, the kind of computation that powers the computer in your home, is based on how humans compute. It breaks down all computations into their most fundamental parts: the binary digits 0 and 1. Nowadays, our computers use bits – a portmanteau word from binary digits – because they are easy to implement with switches that are either in the on or off position.

Quantum computation is based on how the universe computes. It contains all of , but also incorporates a couple of new concepts that come from .

Instead of the bits of classical computation, quantum computing has qubits. However, the outcome from a quantum computation is exactly the same as that from a classical computation: a number of bits.

The difference is that, during the computation, the computer can manipulate qubits in more ways that it can with bits. It can put qubits in a superposition of states and entangle them.

Both superposition and entanglement are concepts from quantum mechanics that most people are not familiar with. Superposition roughly means that a qubit can be in a mixture of both 0 and 1. Entanglement denotes correlation between qubits. When one of a pair of entangled qubits is measured, that immediately shows what value you will get when you measure its partner. This is what Einstein referred to as "spooky action at a distance."

The mathematics needed for a full description of is daunting, and this background is needed to design and build a quantum computer. But the mathematics needed to understand quantum computation and to start designing quantum circuits is much less: High school algebra is essentially the only requirement.

Quantum computing and you

Quantum computers are only just starting to be built. They are large machines that are somewhat unreliable and not yet very powerful.

What will they be used for? Quantum computing has important applications in cryptography. In 1994, MIT mathematician Peter Shor showed that, if quantum computers could be built, they would be able to break current internet encryption methods. This spurred the construction of new ways of encrypting data that can withstand quantum attacks, launching the age of post-quantum cryptography.

It also looks as though quantum computing will probably have a large impact on chemistry. There are certain reactions that classical computers have difficulty simulating. Chemists hope that quantum computers will be efficient at modeling these quantum phenomena.

But I don't think it makes much sense to speculate about what most people will be doing with quantum computers in 50 years. It may make more sense to ask when will become something that anyone can use from their own home.

The answer is that this is already possible. In 2016, IBM added a small quantum computer to the cloud. Anyone with an internet connection can design and run their own quantum circuits on this computer. A quantum circuit is a sequence of basic steps that perform a quantum calculation.

Not only is IBM's quantum computer free to use, but this quantum computer has a simple graphical interface. It is a small, not very powerful machine, much like the first home computers, but hobbyists can start playing. The shift has begun.

Humans are entering an age when it is straightforward to learn and experiment with quantum . As with the first home computers, it might not be clear that there are problems that need to be solved with computers, but as people play, I think it's likely they will find that they need more power and more features. This will open the way for new applications that we haven't yet imagined.


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Mar 26, 2019
Use? Neural nets running on QCs

Mar 26, 2019
When one of a pair of entangled qubits is measured, that immediately shows what value you will get when you measure its partner. This is what Einstein referred to as "spooky action at a distance."


It's not quite like that. It's more like finding your socks in the drawer, which informs you directly that you won't find the socks in the laundry basket. This is completely obvious.

The quantum weirdness comes from the fact that the socks could be in the basket or the drawer all the way up to the point you look, which seems to require some communication between the drawer and the basket to inform the other of the contents of the one that was opened.

The weirdness is solved when you consider that the same observer can't look into both simultaneously. Even if you had two people peek in on the same moment, who got the socks isn't decided until they come together to compare the results - they remain in superposition until the information has had time to propagate


Mar 26, 2019
"I think there is a world market for maybe five quantum computers."

Mar 26, 2019
The issue is that people take a "god's eye view" of the situation, but they forget that nobody can observe both realities at once. If you see reality A first (the socks are in the drawer), then you become part of that reality, if you see B first (the socks are in the basket), you become part of that reality, and when A comes together with B at some later time, the resulting local reality where you are changes again so A doesn't contradict B - and nobody is the wiser.

Whether your resulting reality is "A not B", or "B not A", again doesn't matter - it remains in superposition - until some other piece of information or a new interaction demands you to pick one. The superposition just keeps on growing through chains of interaction and getting more and more elaborate through time and space, or it runs into a logical circle with itself and spontaneously collapses into a single possibility.

Maybe that's the big bang - who knows.


Mar 26, 2019
When one of a pair of entangled qubits is measured, that immediately shows what value you will get when you measure its partner. This is what Einstein referred to as "spooky action at a distance."


It's not quite like that. It's more like finding your socks in the drawer, which informs you directly that you won't find the socks in the laundry basket. This is completely obvious.

The quantum weirdness comes from the fact that the socks could be in the basket or the drawer all the way up to the point you look, which seems to require some communication between the drawer and the basket to inform the other of the contents of the one that was opened.

If you remember when you last did laundry, this shouldn't be a problem.
Of course there always is that one missing sock dilemma...

Mar 26, 2019
If you remember when you last did laundry, this shouldn't be a problem.
Of course there always is that one missing sock dilemma...


All washing machines and dryers contain a singularity. They cause socks to travel to other places and times through a wormhole, and the un-pairing of socks happens when one gets across the event horizon while the spinning of the drum gives it enough energy to depart from its anti-pair.

How you get them back is, you put the unpaired sock back in the machine, and by mutual attraction they re-combine across the wormhole and get pulled back into the same location in space-time.

Mar 26, 2019
Though some argue that the action of putting the unpaired sock in the machine is exactly what rips its anti-pair from the past in the first place, and the sock was never actually un-paired - one of them simply took a shortcut through time.

This is evident from the fact that one of the socks ends up much more worn and linty than the other, suggesting more time has passed. Some physicists claim that this is because it has been rolling on the outside of the drum and simply re-entered through the lip, but this "multiple dimensions" theory cannot be falsified because nobody can view the reverse side of the drum, so it remains an unscientific hypothesis.

Mar 26, 2019

Of course there always is that one missing sock dilemma...

And...therein lies the premise of quantum theory. That sock could probably be anywhere, right up to the moment you see it.

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