Google says that it has achieved quantum supremacy, a major milestone towards the development of quantum computers. At least, it seems to have. The announcement came in a paper that was reportedly published on the NASA website before being pulled, according to the The Financial Times which retrieved a copy before it disappeared. “To our knowledge,” Google’s paper read, “this experiment marks the first computation that can only be performed on a quantum processor.” The Google research paper was titled “Quantum supremacy using a programmable superconducting processor.”

Google’s quantum computer was reportedly able to solve a calculation — proving the randomness of numbers produced by a random number generator — in 3 minutes and 20 seconds that would take the world’s fastest traditional supercomputer, Summit, around 10,000 years. This effectively means that the calculation cannot be performed by a traditional computer, making Google the first to demonstrate quantum supremacy.

Doing in minutes what would otherwise take thousands of years

Despite hitting the milestone, it’s likely that quantum computers capable of tackling practical tasks are still years away. However, once developed, the computers are expected to have huge implications for areas as diverse as cryptography, chemistry, artificial intelligence, and machine learning. Google expects the power of quantum computers to expand at a “double exponential rate,” whereas traditional computers have long been pegged to Moore’s Law, which saw power double every 18 months or so.

Quantum computing in a nutshell: Quantum computing is all about qubits, or quantum bits. These are the basic units of information used by quantum computers. Unlike regular bits, which store data as either 1s or 0s, qubits take advantage of the quantum phenomenon known as superposition. This means they essentially exist as 1s and 0s simultaneously. The advantage of this in computing is that it exponentially increases the amount of information you can process. A pair of qubits that can exist as either 1s or 0s can embody four possible states. Three qubits can embody eight. But three hundred qubits can embody more states than there are atoms in the Universe.

Google previously said that it hoped to achieve quantum supremacy by the end of 2017, however the 72-qubit system it developed proved too difficult to control. Following this, Google developed a 53-qubit design called Sycamore, which was used to achieve the recent breakthrough.

However, the significance of Google’s announcement was disputed by at least one competitor. Speaking to the FT, IBM’s head of research Dario Gil said that Google’s claim to have achieved quantum supremacy is “just plain wrong.” Gil said that Google’s system is a specialized piece of hardware designed to solve a single problem, and falls short of being a general-purpose computer, unlike IBM’s own work.

IBM is a fierce competitor of Google’s in the race to develop quantum computers. Earlier this year it unveiled the Q System One. Although it was still far from being a practical computing device, IBM’s breakthrough was to make it much more reliable than previous quantum machines. Quantum computing chips are very unstable, and prone to interference from heat and electricity. IBM’s new design was able to minimize this interference, the company said.

Others were more optimistic about the development. “Google’s recent update on the achievement of quantum supremacy is a notable mile marker as we continue to advance the potential of quantum computing,” the director of quantum hardware at Intel, Jim Clake, said. “We along with the industry are working to quickly advance all of those areas to realize the true potential of quantum computing. And while development is still at mile one of this marathon, we strongly believe in the potential of this technology.“

The University of Southern California’s Daniel Lidar also praised the way Google’s system reduced the problem of “crosstalk,” which is where a quantum computer’s qubits interfere with one another. “[Google has] demonstrated a path to scalable quantum computing,” he told the FT, “Once you have a fully error-corrected quantum computer, the sky’s the limit.”

Google did not immediately respond to a request for comment.