Bit by Bit is a weekly column focusing on technical advances each and every week across multiple spaces. My name is Adam Conway, and I've been covering tech and following the cutting-edge for a decade. If there's something you're interested in and would like to see covered, you can reach out to me at adam@xda-developers.com.

Quantum computing is an incredibly interesting field of research at present, with companies making massive strides over the years. One of the fundamental building blocks of a quantum chip is the "qubit", which is an analogous component to a "bit" in regular computing. While a bit can hold a value of 0 or 1, qubits can hold values of 0, 1, or a "superposition" which represents 0, 1, and all of the positions in between. One fundamental property of quantum computing might prove to be a problem for modern encryption, though.

What is Google's Willow?

A major leap in quantum computing

Google has been working on quantum computing since 2012, where the "vision" of the group was to create a large-scale quantum computer that could actually harness quantum mechanics. The end goal is to create genuinely useful experiences for real-world applications, and Willow is the latest step in Google's roadmap to achieving that.

Errors are a huge challenge when it comes to quantum computing. Qubits have a tendency to rapidly exchange information with their environment, making it difficult to protect the information needed to complete a computation. The more qubits you use, the more errors you'll experience. However, Google's breakthrough here is that in Willow, the more qubits were used, the more errors were reduced. Google puts it as saying that with larger arrays of physical qubits, scaling up from a grid of 3x3 encoded qubits, to a grid of 5x5, to a grid of 7x7, each time, they were able to cut the error rate in half. In other words, an exponential reduction in the error rate. Willow uses 105 qubits.

In quantum computing, this is called "below threshold," where you drive down errors while scaling up in qubits. This is necessary for demonstrating real progress in error correction, as otherwise, the errors will scale with qubits and cause problems. This is also one of the first-ever examples of real-time error correction in a superconducting quantum system, and Google's own benchmarks prove that this is the real deal. A significant part of error reduction is in cooling, and huge advancements have been made across the board.

Google's engineers tested Willow using the random circuit sampling (RCS) benchmark. It's a standard in the field, considered to be the hardest benchmark that can be done on a quantum computer today. It essentially checks whether a quantum computer is doing something that couldn’t be done on a classical computer. Any team building a quantum computer should check first if it can beat classical computers on RCS; otherwise there is strong reason for skepticism that it can tackle more complex quantum tasks. This includes a computation that a classical computer would take 10 septillion years to complete, whereas Willow completed it in just five minutes.

Will quantum computing break encryption as we know it?

It probably will

There comes a very scary challenge when we talk about quantum computing, and that challenge relates to what happens to encryption. Shor's algorithm, written by American mathematician Peter Shor, is a quantum computing algorithm that can find the prime factors of an integer, which would break public-key cryptography schemes like RSA and both Finite Field and Elliptic Curve Diffie-Hellman key exchanges. The biggest thing holding back Shor's algorithm right now is the number of qubits that are required for it to work, with some estimates saying that you may need thousands of qubits to use Shor's algorithm to break modern encryption standards.

With that said, Shor's algorithm has been demonstrated to work with smaller values, though it makes assumptions that the quantum computer it runs on will be free of noise and errors, something that may prove to be a problem in the real world. Likewise, this is why Google's error correction efforts are a big deal, as errors are an increasingly bigger problem when it comes to quantum computing as time goes on and more qubits are added. Public-key cryptography underpins much of the modern internet, securing everything from emails to online banking. Shor's algorithm, when run on a sufficiently advanced quantum computer, could dismantle these cryptographic protocols by efficiently factoring large numbers. RSA, a widely used encryption standard, relies on the assumption that factoring large integers is computationally infeasible. Quantum computing challenges this assumption.

Governments and researchers are already preparing for a "post-quantum" world. The National Institute of Standards and Technology (NIST) in the U.S. has been working on quantum-resistant cryptographic algorithms, selecting candidates designed to withstand attacks from quantum systems. These algorithms focus on problems that are hard for both classical and quantum computers, such as lattice-based cryptography or hash-based signatures.

Quantum computing's timeline is notoriously difficult to predict. While Willow represents a pretty big leap forward, practical, large-scale quantum computers may still be decades away. Yet, the advancements we’re seeing today indicate that the field is progressing faster than many anticipated.

For now, all the world can do is watch as companies like Google, IBM, and startups like IonQ and Rigetti Computing race toward full-scale quantum computing. These breakthroughs are two-fold in terms of ramifications; they not only solve problems we currently find insurmountable but also create challenges we’ve never faced before. You can't play Doom on a quantum computer yet, but that (and so much more) may be in our near enough future.