Scientists are running into issues that today’s computing technology cannot possibly solve because of the limitations inherent to the way we construct computers. Mainly, we can’t cram enough computing power into the microarchitecture of our multi-core processors. So engineers are looking toward quantum mechanics and physics for the future of computing.
How is a quantum computer different from the computer this blog was typed on? Quantum computer designs are sometimes as big as a multi-story building or a soccer field because of how they process information and the kind of cooling they require (more on that later). They help us study things like molecular compositions. Classic computers aren’t capable of solving quantum problems, such as how nitrogen can become ammonia, how a caffeine molecule binds together, or how to create better, faster cryptography for sensitive data. Scientists believe that quantum computers will help us solve global problems like the climate crisis, personalized medicine, or things we can’t even conceive of currently.1,2
A classic computer has a processor that uses bits, and those bits are the 1 and 0—either there’s an electrical pulse or there isn’t—flowing through the processor bus. Today’s computers use binary code, and you can never have a 1 and a 0 flowing through the same circuitor transistor at the same time. These computers rely on multi-core processors to provide the fast throughput demanded by modern apps and services. Multiple cores enable the computer to execute multiple processes in parallel. But today’s processors are running out of room on the chip, so we can’t squeeze more power out of them without shrinking our microarchitectures even further—and today’s processors are already measured in nanometers. That’s one billionth of a meter, used to measure the size of atoms and molecules.
Quantum computers use something called a “qubit,” short for quantum bit. Instead of electrical impulses, quantum computers use subatomic particles, which can exist in two different states simultaneously. In classic computing terms, that means that a 1 and a 0, a binary number, could exist at the same time within the same thread. A qubit doesn’t just store one binary number, though—it stores all possible combinations of binary numbers.[i] This makes quantum computers much faster than classic computers. It also makes them massive—we would need more classic computers than there are atoms in the visible universe to store the same amount of information stored in a qubit.1
How Do You Use Subatomic Particles in Computing?
In classic computing, processors are made out of silicon to conduct electricity and supply the bits that power processes. Qubits are much more slippery than bits. Jerry Chow of IBM’s Thomas J. Watson Research Center likens using qubits to balancing an egg on a needle—it’s doable, but any external influence could cause the egg to fall. Noise, heat, and vibrations can cause things to go “sunny side up.”[ii]
Some scientists use light to extract subatomic particles, so they need to find the right material to “trap” the particles in the desired state (a 1, a 0, or a 0+1). Professor Jelena Vuckovic, who’s part of the electrical engineering faculty at Stanford, is working on creating the right kind of semiconductor material. When she shines a laser beam at the material, the material should be able to contain a spinning electron, a subatomic particle, within a molecular cage to reveal which way the particle is spinning, as a 1, a 0, or a 0+1. So far, her lab has designed three kinds of crystalline materials to trap electrons.[iii]
One of these materials, the quantum dot is a certain kind of crystal that can force a high-powered laser to produce two photons, a subatomic particle of light. China is using the quantum dot in their development of a five-qubit quantum computer, one of the largest quantum computers built to-date.
The Trouble with Superposition
Many quantum computers require cryogenics (extreme cold) to operate—either as a means of capturing a subatomic particle in a specific state or to achieve an environment devoid of electrical resistance, which some quantum computing components require. This is because of the quantum property “superposition,” which is the ability to exist in all possibilities at the same time. The 0+1, the superposition state of quantum computing, is delicate to maintain.Chow and team, who are building qubits out of superconductive material, which requires keeping the quantum computer colder than outer space.2 By maintaining such a low temperature, the quantum computer can preserve the qubit in the desired state, which enables the team to use electrical signals for controllability. The team believes that the design of this quantum processor is a building block toward scalable quantum computing.
Two of Vuckovic’s three experimental quantum chips require cryogenic cooling to operate, but the lab has had some success with a material that can operate at room temperature: a modified crystalline compound of silicon and carbon, with a deliciously science-fiction name, “carborundum.”
The Future of Quantum Computing
The construction of quantum computers is a feat by itself, but there’s still the consideration of who will program the quantum computers of the future. Quantum computing programmers will need an understanding of quantum physics, which presents a departure from the traditional world of coding. To provide incentive to learn and explore, many companies are making their quantum computers available via the cloud and open-source tools.
What kind of unknowable things will quantum computers help us to discover? How many qubits does the human brain have? And will quantum computers allow us to develop thinking machines whose software enables them to be imprinted and changed by external and internal factors?
These are the quantum-computing possibilities we ask ponder, but there’s no telling if scientists will create such advanced technology within our lifetime. Perhaps quantum computing will increase our capacity to create and imagine, and allow humankind to achieve whatever it can imagine For now, we’ll be exploring the Quantum Computing Playground and keeping an eye on quantum computing news.
Find us on Twitter @ProwessConsult for more about the future of computing.
[ii] TED Institute. “The future of supercomputers? A quantum chip colder than outer space | Jerry Chow | TED Institute.” December 2015. www.youtube.com/watch?v=VsBuuwGj3zs&feature=youtu.be&t=6m27s.
[iii] Phys.org. “New materials bring quantum computing closer to reality.” May 2017. https://phys.org/news/2017-05-materials-quantum-closer-reality.html.