In 1946 the Electronic Numerical Integrator and Computer, or the ENIAC, was introduced. The world's first commercial computer was intended to be used by the military to project the trajectory of missiles, doing in a few seconds what it would otherwise take a human mathematician about three days. It's 20,000 vacuum tubes (the glowing glass light bulb-like predecessors to the transistor) connected by 500,000 hand soldered wires were a marvel of human ingenuity and technology.
Imagine if it were possible to go back to the developers and users of that early marvel and make the case that in 70 years there would be ten billion computers worldwide and half of the world's population would be walking around with computers 100,000,000 times as powerful as the ENIAC in their pants' pockets.
You'd have been considered a lunatic!
I want you to keep that in mind as you resist the temptation to do the same to me because of what I'm about to share.
Digital computers will soon reach the limits of demanding technologies such as AI. Consider just the impact of these two projection: by 2025 driverless cars alone may produce as much data as exists in the entire world today; fully digitizing every cell in the human body would exceed ten times all of the data stored globally today. In these and many more cases we need to find ways to deal with unprecedented amounts of data and complexity. Enter quantum computing.
You've likely heard of quantum computing. Amazingly, it's a concept as old as digital computers. However, you may have discounted it as a far off future that's about as relevant to your life as flying cars. Well, it may be time to reconsider. Quantum computing is progressing at a rate that is surprising even those who are building it.
Understanding what quantum computers are and how they work challenges much of what we know of not just computing, but the basics of how the physical world appears to operate. Quantum mechanics, the basis for quantum computing, describes the odd and non-intuitive way the universe operates at a sub-atomic level. It's part science, part theory, and part philosophy.
Classical digital computers use what are called bits, something most all of us are familiar with. A bit can be a one or a zero. Quantum computers use what are called qubits (quantum bits). A quibit can also be a one or a zero but it can also be an infinite number of possibilities in between the two. The thing about qubits is that while a digital bit is always either on (1) or off (0), a qubit is always in what's called a superposition state, neither on nor off.
Although it's a rough analogy, think of a qubit as a spinning coin that's just been flipped in the dark. While it's spinning is it heads or tails? It's at the same time both and neither until it stops spinning and we then shine a light on it. However, a binary bit is like a coin that has a switch to make it glow in the dark. If I asked you "Is it glowing?" there would only be two answers, yes or no, and those would not change as it spins.
That's what a qubit is like when compared to a classical digital bit. A quibit does not have a state until you effectively shine a light on it, while a binary bit maintains its state until that state is manually or mechanically changed.
Don't get too hung up on that analogy because as you get deeper into the quantum world trying to use what we know of the physical world is always a very rough and ultimately flawed way to describe the way things operate at the quantum level of matter.
However, the difficulty in understanding how quantum computers works hasn't stopped their progress. Google engineers recently talked about how the quantum computers they are building are progressing so fast that that they may achieve the elusive goal of what's called "quantum supremacy" (the point at which quantum computers can exceed the ability of classical binary computer) within months. While that may be a bit of stretch, even conservative projections put us on a 5-year timeline for quantum supremacy.
Quantum vs Classical Computing
Quantum computers, which are built using these qubits, will not replace all classical digital computers, but they will become an indispensable part of how we use computers to model the world and to integrate artificial intelligence into our lives.
Quantum computing will be one of the most radical shifts in the history of science, likely outpacing any advances we've seen to date with prior technological revolutions, such as the advent of semiconductors. They will enable us to take on problems that would take even the most powerful classical supercomputers millions or even billions of years to solve. That's not just because quantum computers are faster but because they can approach problem solving with massive parallelism using the qualities of how quantum particles behave.
The irony is that the same thing that makes quantum computers so difficult to understand, their harnessing of natures smallest particles, also gives them the ability to precisely simulate the biological world at its most detailed. This means that we can model everything from chemical reactions, to biology, to pharmaceuticals, to the inner workings of the universe, to the spread of pandemics, in ways that were simply impossible with classical computers.
A Higher Power
The reason for the all of the hype behind the rate at which quantum computers are evolving has to do with what's called doubly exponential growth.
The exponential growth that most of us are familiar with, and which is being talked about lately, refers to the classical doubling phenomenon. For example, Moore's law, which projects the doubling in the density of transistors on a silicon chip every 18 months. It's hard to wrap our linear brains around exponential growth, but it's nearly impossible to wrap them around doubly exponential growth.
Doubly exponential growth simply has no analog in the physical world. Doubly exponential growth means that you are raising a number to a power and then raising that to another power. It looks like this 510^10.
What this means is that while a binary computer can store 256 states with 8 bits (28), a quantum computer with eight qubits (recall that a qubit is the conceptual equivalent of a digital bit in a classical computer) can store 1077 bits of data! That's a number with 77 zeros, or, to put it into perspective, scientists estimate that there are 1078 atoms in the entire visible universe.
Even Einstein had difficulty with entanglement calling it, "spooky action at a distance."
By the way, just to further illustrate the point, if you add one more qubit the number of bits (or more precisely, states) that can be stored just jumped to 10154 (one more bit in a classical computer would only raise the capacity to 1078).
Here's what's really mind blowing about quantum computing (as if what we just described isn't already mind-blowing enough.) A single caffeine molecule is made up of 24 atoms and it can have 1048 quantum states (there are only 1050 atoms that make up the Earth). Modeling caffeine precisely is simply not possible with classical computers. Using the world's fastest super computer it would take 100,000,000,000,000 times the age of the universe to process the 1048 calculations that represent all of the possible states of a caffeine molecule!
So, the obvious question is, "How could any computer, quantum or otherwise, take on something of that magnitude?" Well, how does nature do it? That cup of coffee you're drinking has trillions of caffeine molecules and nature is doing just fine handling all of the quantum states they are in. Since nature is a quantum machine what better way to model it than a quantum computer?
The other aspect of quantum computing that challenges our understanding of how the quantum world works is what's called entanglement. Entanglement describes a phenomenon in which two quantum particles are connected in such a way that no matter how great the distance between them they will both have the same state when they are measured.
At first blush that doesn't seem to be all that novel. After all, if I were to paint two balls red and then separate them by the distance of the universe, both would still be red. However, the state of a quantum object is always in what's called a superposition, meaning that it has no inherent state. Think of our coin flip example from earlier where the coin is in a superposition state until it stops spinning.
If instead of a color its two states were up or down it would always be in both states while also in neither state, that is until an observation or measurement forces it to pick a state. Again, think back to the spinning coin.
Now imagine two coins entangled and flipped simultaneously at different ends of the universe. Once you stop the spin of one coin and reveal that it's heads the other coin would instantly stop spinning and also be heads.
If this makes your head hurt, you're in good company. Even Einstein had difficulty with entanglement calling it, "spooky action at a distance." His concern was that the two objects couldn't communicate at a speed faster than the speed of light. What's especially spooky about this phenomenon is that the two objects aren't communicating at all in any classical sense of the term communication.
Entanglement creates the potential for all sorts of advances in computing, from how we create 100 percent secure communications against cyberthreats, to the ultimate possibility of teleportation.
Room For Possibility
So, should you run out a buy a quantum computer? Well, it's not that easy. Qubits need to be super cooled and are exceptionally finicky particles that require an enormous room-sized apparatus and overhead. Not unlike the ENIAC once did.
You can however use a quantum computer for free or lease its use for more sophisticated applications For example, IBM's Q, is available both as an open source learning environment for anyone as well as a powerful tool for fintech users. However, I'll warn you that even if you're accustomed to programming computers, it will still feel as though you're teaching yourself to think in an entirely foreign language.
The truth is that we might as well be surrounded by 20,000 glowing vacuum tubes and 500,000 hand soldered wires. We can barely imagine what the impact of quantum computing will be in ten to twenty years. No more so than the early users of the ENIAC could have predicted the mind-boggling ways in which we use digital computers today.