Quantum Computers: Something and Nothing, All at Once
The competition to move quantum computers forward has been called “the most important tech contest since the space race,” promising new breakthroughs in cybersecurity, communication technologies, and the discovery of new drugs and physical materials. But what is a quantum computer, really? In this article we’ll look at the tech that’s driving the race for quantum supremacy: why it matters, and who today is making the most important steps.
Quantum technology relies on laws of physics at an atomic scale, one that no human has ever seen or experienced. To better understand the complex and downright mysterious technology driving this tech, we’re forced to take a leap of our imagination. So, let’s begin with a quantum fairytale.
a quantum wizard
Imagine yourself waking up, locked in the center of a vast and musty room, filled floor-to-ceiling with wooden cabinets as far as your eye can see. A wizard gives you a problem to solve before you can escape: find a single phrase, written on a piece of paper, hidden in the endless hall of cabinets. Find the right word, and the room will disappear. You’ll wake up from this dream, free to get your morning cup of coffee.
The process may seem impossible, but you start searching: open a cabinet, look inside, call out to see if you’ve discovered the password. Nothing happens, and you move on.
In essence, you’re acting just like the computers we have today: where energy running through a circuit board can only be directed toward a single task at a time.
Now, imagine that the wizard gets bored: he clearly didn’t think this through, and he has somewhere else to be. To speed things up, he creates a couple thousand copies of you, all set out on the same task. When you find it, all your copies will recombine into one, and you can go get your cup of coffee. Now, the task goes much faster.
In this fairy tale, you’re seeing the difference between“classical” computing and quantum computing. In a classical computer, all effort is directed to a single piece of data at a time. In a quantum computer, that same effort can be applied to multiple pieces of data, simultaneously, in search of the same answer in different places.
In the world of quantum computers, technology operates through the logic of quantum physics. It’s a world where massive data sets are instantaneously available across an entire network, without downloads or uploads. It’s a world where your credit card number disappears into chaos the minute someone tries to steal it. It’s a world where all of the rules of the universe, as we perceive it, are upended, and new ways of thinking and acting are cracked wide open.
From Binaries to Spectrums
Quantum computing is the result of building and arranging things on scales smaller than anything that’s come before, giving us a better understanding of nanoscale worlds at the level of particles and waves. When you zoom into the universe at this scale — one millionth of the size of a human hair — things behave in ways that don’t make sense in our macro landscape. Building a computer in this terrain of particles and waves means working by the logic of our quantum fairytale.
Today’s computers use technology and rules taken from the observable world of what we can see and touch. Energy either buzzes through transistors on a circuit board, or it doesn’t. That’s a pretty straightforward “on” or “off,” giving us the binary logic of 1 (buzz) or 0 (no buzz). These 1’s and 0’s are arranged in pulses, patterns that software can decode and use. In this world, even the tiniest pulse of energy registers as energy. There’s nothing “between” a 0 and a 1, because either there’s no energy at all, or there is: nothing “sort of exists.”
It’s a bit like thinking of sleep as either being awake, or not. That’s a binary. But we know that we can be “half-asleep,” waking from a dream world (perhaps a room of infinite cabinets, being harassed by an annoyed wizard?) into the waking one. What about in-between, where your quantum twins are racing through this bizarre maze of cabinets, but you can still hear the grating drone of your cursed alarm clock from the waking side of life? To grasp what a quantum computer does, consider your groggiest mornings. In quantum computing, energy and information works in a whole new way, existing mostly in these “in-between” states of uncertainty, where you can be awake and asleep at once.
Moving away from fairytales and metaphors, we know that light can be a particle and a wave, and it can also be neither; it can also be both. For quantum processing, you can have 0 or 1, neither 0 nor 1, or both 0 and 1. It’s called a “superposition,” and it’s what separates the “bits” in your laptop from the qubits of a quantum machine. A qubit can hold multiple — literally infinite — ”bits” within itself, which can all coexist as a single, dense “bit” of information, and can contain various arrangements of off-and-on states. In our fairytale, you’re inside a qubit, with the same task applied to various sets of data, simultaneously.
That’s what makes a quantum computer so remarkable. You can’t measure where a particle is and know how fast it’s moving at the precise same moment. As information moves through qubits, more numbers can be analyzed at once, and when that data isn’t being looked at (for example, once the problem is solved), the whole room dissolves. Essentially, qubits can contain and process information at the same time.
Spooky Action at a Desktop
This brings us to another extremely weird, mind-breaking capacity of this technology: quantum entanglement, what Einstein called “spooky action at a distance.” Sometimes, two particles, regardless of their distance from one another, can trigger a response in the other particle. Entangled qubits vastly multiply the storage capacity of a single qubit.
Think back to the cabinet room of our quantum fairytale. When the wizard creates these infinite replicas to speed up your task, you were, in essence, entangled with your copies. You didn’t have to explain yourself to any of your cloned colleagues, some of whom were too far away to ever even talk to: they were all doing what you were doing, because you were doing it. They just applied your task to different cabinets. Entanglement allows you to look at one particle and get all the information you need, regardless of where other particles are.
Scientists are already producing entanglements with lasers. They can build chains where the links don’t touch, but still pull the wheels in the same direction: one particle “knows” what to do based on the actions of some other particle. We could encourage entanglements to provide direct access to all of the information in a machine at once, just as your dream clones could tackle the task of searching every cabinet. Just the same, every new qubit added to a quantum computer’s processor provides an exponential increase in power.
This strange relationship holds a compelling promise for the future of telecommunications. Instead of downloading a copy of a large file across hundreds of machines, you could simply trigger a dance of entangled particles across vast distances, making a file materialize simultaneously on either end of a network. Researchers have already done it, creating harmonious alignments of particles that could be read on either side of a 100km fiber optics cable back in 2015. That’s the same fiber optic cable in place wherever high-speed internet exists: the communications potential of quantum computers could be met using existing infrastructure. Beyond that, though, we reach amazing new capacities, with a Chinese research paper showing the same results through different means at a distance of 1,200km.
A Crypto Killer?
As usual, new tech brings new fears. For quantum computers, the chorus of concern is that they will upend today’s models for digital encryption, because they can process many more equations simultaneously. Some fear that a future quantum computer could create a “blockchain killer,” disrupting the foundational principles of cryptography and cryptocurrencies.
Those “crypto” prefixes refer to common roots within digital encryption technology. For BitCoin or secure messaging to work, machines translate your information into seemingly random gobbledygook, and transmit that gobbledygook to wherever it needs to go. Once it gets to the intended recipient, they (or a machine) decodes the gobbledygook into something useful. This process only works if the gobbledygook has some relation to the original message, and until now, we’ve relied on the limits of traditional computer processing power to ensure that no person or machine could simply “guess” what that relationship is: it requires a key.
Quantum computers, with their capacity to hold essentially every number in a superposition at the same time, would be much faster at figuring out relationships between your original message and the protecting gobbledygook without your key.
But that fear is a bit overwrought for now. Cracking BitCoin encryption would require a 1,500-qubits machine, which is well beyond anything out there today: Google’s Bristlecone has 72 qubits; IBM has reached 50 (IBM Q, its commercial version accessible via the cloud, offers 20). D-Wave’s machine at the University of Southern California-Lockheed Martin Quantum Computing Center offers 1,092 qubits, but there is some controversy about how that’s measured and whether comparisons to other quantum machines is fair, given the differences in how they’re defined.
While advances that could disrupt today’s methods of encryption are inevitable, the same power that would derail today’s crypto would be available to develop new methods of encryption. Most promising is the simple fact that you can’t measure the speed of a particle and its position at the same time. That means data could be designed to be transferred between authorized parties and would simply collapse if it was observed by anyone else. That means the “cryptopocalypse” could be solved even sooner than it arrives, which is the focus of quantum cryptography.
Credit card transactions, private text messages, and cryptocurrency purchases would be either dangerously vulnerable to malicious actors, or forced to centralize through services run by governments or corporations powerful enough to support these transactions. Both scenarios raise ethical questions.
Quantum computers aren’t inherently fast. In fact, they’re only faster than classical computers at a handful of specific tasks: an army of clones all focused on one task is only useful in a narrow range of situations. For everything else, a quantum machine is, at best, only as fast as a traditional processor. Crucially, all of the quantum computers that exist today have limits on what they can do and how long they can do it.
They require temperatures of absolute zero (–273.15°C, –459.67°F) and can collapse from even the slightest fluctuation of energy (a cell phone, in the same room, could break the whole system). Maintaining entanglements is harder than herding molecule-sized cats, with the world record resting at around 100 microseconds. That’s certainly not enough time for our dream wizard to get bored (never mind the time you’d need to find the proper cabinet).
Quantum computers are being developed alongside AI and algorithmic applications that could come up with new ways of using entanglement and superpositions to solve problems, but that isn’t an easy process. Most of what we know about computer science has to be re-written from scratch. One of the most promising potentials of quantum computing is that it breaks the frame around traditional computer science, inspiring a friendly competition that benefits both. Last year, Ewin Tang, an 18-year-old undergraduate at the University of Texas, looked at a problem that quantum computers had been able to tackle faster than any other tech — and then designed an algorithm for a classical computer that did it just as well.
However, recent signs suggest that advancements could start happening at a much faster pace. Quantum computers tore into 2019 at the annual Consumer Electronics Show in Las Vegas, where IBM revealed the first commercial application of a 20-qubit quantum computer, the IBM Q. The business model for this machine isn’t centered on production and distribution of a product, but renting time to users via the cloud. The machine is a prototype that, again, doesn’t do anything “faster” than an equivalent traditional computer. What’s groundbreaking is its existence as a testing space for quantum programming, with some specialized users using it to expand their theoretical applications.
CERN, the European Laboratory for Particle Physics, is working with IBM “to investigate how to apply quantum machine learning techniques to classify collisions produced at the Large Hadron Collider,” the world's largest and most powerful particle accelerator. The market for quantum computers is still fixed within research and development, likely to be of interest to the same players who make use of the world’s most powerful computers today. But for now, we can dream.
swissnex San Francisco was one of the partners attending the 2019 Consumer Electronic Show to scout new trends and to support the first Swiss Pavilion, a Swiss government-backed showcase highlighting the latest science and technology from Switzerland.
Once called "the Harry Potter of the Digital Vanguard," Eryk Salvaggio is a writer, artist, and researcher at swissnex San Francisco. He previously studied new media art and journalism at the University of Maine and Global Media at the London School of Economics.