Quantum computing is the next frontier of computing that promises to upend what we think a computer is capable of. The term comes from the fact that a quantum computer relies on properties of quantum physics to perform calculations using what are called qubits, or quantum bits. This contrasts with the classical computers we use today, including everything from our current supercomputers to the smartphones in our pocket. Classical computers rely on properties of classical physics and perform calculations using the bits we all know and love.

Quantum computers, in theory, will be able to perform calculations in seconds that would take a normal classical computer—even classical supercomputers—tens of thousands of years to perform. Because of this, quantum computers will revolutionize everything from medicine to encryption—so it’s no wonder nation-states across the world are in an arms race to build the first practical quantum computers.

Major companies involved in the quantum computing race include Google and IBM. And as of today, Google has announced that it’s in the lead above all others. The company published a paper in the journal Nature where it claims it has achieved “quantum supremacy”—that is, it has created a computer that can perform something no classical computer ever could. As the Verge reports, the search giant says its 54-qubit processor, known as Sycamore, performed a task (which was generating random numbers) in just 200 seconds. This same task, Google says, would have taken the most powerful supercomputer in the world today 10,000 years to complete.

But quantum computing competitor IBM quickly published a blog post disputing Google’s quantum supremacy claim:

Recent advances in quantum computing have resulted in two 53-qubit processors: one from our group in IBM and a device described in the leaked preprint from Google. In the preprint, it is argued that their device reached “quantum supremacy” and that “a state-of-the-art supercomputer would require approximately 10,000 years to perform the equivalent task.” We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity. This is in fact a conservative, worst-case estimate, and we expect that with additional refinements the classical cost of the simulation can be further reduced.

IBM goes on to say that since a classical computer could do in two and a half days what Google’s quantum computer did in 200 seconds, Google has not achieved quantum supremacy.

So who’s correct? We’ll have to leave that up to the computer scientists of the world to decide. Now that Google’s paper has been published in Nature, experts will have a chance to scrutinize Google’s claims and methods. The only sure thing is that the quantum computer wars are only starting to heat up.