Critics, including IBM, say that Google was exaggerating its claim and making it look like quantum computers would replace classical computers soon enough.
Google's parent Alphabet recently published a paper claiming that it had achieved Quantum Supremacy, a feat many compared to the first aeroplane flight by the Wright brothers.
Google said its quantum computer solved a problem in three minutes and 20 seconds, which would take the fastest super computer, Summit (owned by the US government), 10,000 years to solve.
Critics, including IBM, hit back saying that Google was exaggerating its claim and making it look like quantum computers would replace classical computers soon enough.
The bone of contention is that Google's quantum computer could process 54 qubits, just one more than IBM's soon to be rolled out 53-qubit computer IBM Q.
What is a qubit?
This is where it gets interesting.
Conventional computers use bits -- 1s and 0s -- as the basis of their calculations.
Basically, they represent "yes" and "no", or "on" and "off".
Quantum computing makes use of a property of sub-atomic particles in which they can simultaneously exist in different states.
A quantum bit, or qubit, can thus be both one and zero at the same time.
This property is called superposition.
When many qubits are taken together, they influence each other's behaviour which delivers exponentially higher number of results.
What's the use?
It's a myth that quantum computers will replace the classical ones.
Both are meant for different applications.
In real world, quantum computers are meant for specialised tasks.
Here's an example.
Say, you have a bowl of water and you introduce bacteria into it.
The bacteria will take many months to grow, and it will take researchers as much time to monitor it.
If you have a quantum computer and you feed all the data of the entire environment, it can simulate the entire system and produce the same result in a matter of seconds.
What next?
Google says it sees potential uses for quantum computing in fields such as machine learning and materials science, chemistry and biology.
IBM, which has a quantum computing research facility in operations for many years, has opened it up external scientists and research to run experiments on its in-house quantum computer.
Both admit, though, that still greater accuracy will be needed to bring those use cases into the real world.
Why?
Qubits need to be cooled to just above absolute zero to reduce noise -- or vibration -- that introduces errors into the calculations.
This problem is yet to be solved completely.
