IBM Calls Out Google's Quantum Supremacy Claims With 53-Qubit Supercomputer

Google Sycamore Processor
There's a good old fashioned nerd fight brewing between the eggheads at IBM and Google. Don't worry, it's not physical—it's a war of words and theoretical concepts. What sparked the debate is Google's claim of achieving "quantum supremacy" with Sycamore, a system outfitted with a 53-qubit processor and how it performs compared to a classical supercomputer in a specific task.

Google conceived an experiment to demonstrate just how capable Sycamore is, noting it can complete a certain benchmark test in 200 seconds, whereas "a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task."

The spunky Mountain View firm details the experiment in a blog post, going over concepts such as bitstrings, quantum interference, quantum physics and mechanics, and so forth.

"The success of the quantum supremacy experiment was due to our improved two-qubit gates with enhanced parallelism that reliably achieve record performance, even when operating many gates simultaneously. We achieved this performance using a new type of control knob that is able to turn off interactions between neighboring qubits," Google explains.

There is quite a bit of technobabble to trudge through, but the gist of the argument is that Google's experiment proves its Sycamore hardware is leaps and bounds better than anything else, based on a random number checking algorithm it ran. IBM disagrees, essentially saying Google's testing is flawed.

"When their comparison to classical was made, they relied on an advanced simulation that leverages parallelism, fast and error-free computation, and large aggregate RAM, but failed to fully account for plentiful disk storage. In contrast, our Schrödinger-style classical simulation approach uses both RAM and hard drive space to store and manipulate the state vector," IBM says.

The difference between 200 seconds and 10,000 years to compete a task is staggering. However, IBM claims the "performance-enhancing techniques employed" by its own hardware—circuit partitioning, tensor contraction deferral, gate aggregation and batching, other things that might make your head spin—reduces the gap significantly. Sycamore would still have an advantage, but in a worst case scenario, IBM says a classical system would take 2.5 days to perform the same task "and with far greater fidelity."

IBM does not stop there. It cautions against reading too much into the term "quantum supremacy," which is a sexy phrase to plop into headlines.

"It is well known in the quantum community that we at IBM are concerned of where the term 'quantum supremacy' has gone...the 'supremacy' term is being misunderstood by nearly all (outside of the rarified world of quantum computing experts that can put it in the appropriate context)," IBM says.

IBM had plenty more to say on the topic (hit the link in the Via field below). In the end, though, IBM is not disparaging of quantum computing, it just takes issue with Google's assertion that Sycamore is the first example of a quantum computer doing something a classical computer is unable to do.