A Quantum Computing Refresher

For many of us, learning about quantum computing is like reading Stephen Hawking’s “A Brief History of Time” — it makes sense in the moment, but the understanding slips away easily. With that in mind, here are five key points to remember about quantum computing.

1. Is it Binary? Yes, No, and Yes and No

A traditional computer (often referred to as classical) runs on binary code: It converts information into ones and zeros, which is an efficient way to run calculations and store or communicate data.

A quantum computer encodes information in quantum particles — such as atoms, ions and photons — that aren’t strictly binary. A quantum bit, or qubit, can represent a zero, a one, or both a zero and a one simultaneously. That attribute, known as a superposition, makes it possible to run incredibly complex calculations very quickly.

A quantum bit can represent a zero or a one or both a zero and one simultaneously. That’s because quantum mechanics deals in probabilities, not certainties.
 
Here’s a good analogy from consulting firm McKinsey & Co. Flipping a coin is the ultimate binary: It lands on either heads or tails. But while the coin spins through the air, it’s not one or the other, but some probability of either or both. By taking advantage of those multiple states, a quantum computer can run a massive number of calculations at one time. (To learn more, check out this article.)

2. Processing Power Grows Exponentially

Another important quantum property is entanglement, which makes it possible to manipulate multiple qubits, as this video explains.

It’s all about math: The more qubits you have, the more ones and zeros you can use to run calculations. “While doubling the number of bits in a classical computer doubles its processing power, adding qubits results in an exponential upswing in computing power and ability,” this article explains.

3. It’s the Ultimate Multitasker

Think about how a computer might solve a maze. A classical computer would run all possible paths, one after the other, to find what works. The more power it has, the faster it can run that sequence.

But a quantum computer, using qubits in superposition, can test all possible paths at once, enabling it to arrive at the solution seemingly instantaneously. So far, that advantage is mainly experimental, due to hardware limitations. As those are overcome, expect to see quantum show off its speed.

4. There Are Still Bugs in the System

Here are some of the challenges that quantum scientists, computer scientists and hardware manufacturers are working to address:

• Decoherence. Qubits are highly sensitive to vibrations, temperature changes and other environmental factors, with slight disturbances knocking them out of superposition and causing errors.
• Error correction. The next challenge is to catch and correct errors as they happen, not just when an outcome looks askew. Experts have zeroed in on a few possible approaches.
• Multiqubit networking. Manufacturers hope to improve performance by having multiple chips or even multiple computers work in tandem. Unfortunately, they are still trying to figure out how to control individual qubits as their numbers increase.

5. Quantum

Numerous companies have developed quantum computers that demonstrate the feasibility of the concept, even as they work on solutions to the problems described above (and others). But the timeline for commercial viability remains elusive. Here are some of the latest estimates:

• Martina Gschwendtner, a consultant in the Munich office of McKinsey, recently told TechTarget that the basic computational components could come together as soon as 2030.
• The Defense Department’s Quantum Benchmarking Initiative is trying to determine if “an industrially useful quantum computer” is feasible by 2033. To be “useful” in this sense, the value of the computer’s computational output should exceed its cost.
• Nvidia Chief Executive Officer Jensen Huang and Meta CEO Mark Zuckerberg have said that quantum computing won’t be a major force for another decade, as reported by Forbes.

This article is excerpted from GovLoop’s “Quantum Computing: What You Need to Know Today.” Download the guide to learn what quantum is, where it’s headed, and how it will impact the government workforce.

Image by Gerd Altmann from Pixabay