What is Quantum Computer and how it works ?

Google claims it has reached a key milestone using a quantum computer to complete a task that a classical computer couldn’t manage, achieving what they call ‘quantum supremacy’, this would be the first time that a quantum computer has definitively beaten the best conventional computer, but it’s something that physicists have been trying to do for years.

Although not everyone is convinced that a normal computer would find this particular task impossible, it certainly seems like the quantum processor solves it faster.

The task is a calculation that is not very useful, It was designed just to demonstrate quantum supremacy and was made to be especially difficult for normal computers to handle.

Google’s quantum computer is called Sycamore, It has just 53 qubits, quantum versions of the ‘bits’ that encode information in a computer. these behave completely differently to regular bits, and are very hard to manipulate. but in theory they should allow the computer

to carry out certain kinds of calculations way faster than a classical machine.

The calculation in this test was to figure out the probability distribution

of all the possible outcomes from a quantum random number generator.

Because the generator creates random numbers using quantum operations,

simulating this distribution on a classical computer is extremely tough.

But Google’s machine only needed to set itself up like the generator,

and then run those operations a bunch of times.

Sycamore produced an answer in just 3 minutes and 20 seconds.

But proving quantum supremacy, means facing off against classical competition.

For that, researchers borrowed the supercomputing might

of the Summit supercomputer at Oak Ridge National Laboratory in Tennessee.

By breaking up the problem into smaller chunks and then extrapolating,

they estimate that Summit would take 10,000 years to finish the same calculation.

If true, this means a quantum computer can do something that is, in practice,

impossible on a classical machine quantum supremacy. but not everyone agrees.

IBM has released a paper claiming that the Summit supercomputer could actually complete

the task in just 2.5 days by using a slightly different technique, scientists will now scrutinize both camps’ calculations, but even if IBM is right, it's still significant that Sycamore was so much faster than the supercomputer.

It's the first time that this kind of quantum speed up has ever been shown.

It wouldn't be the standard definition of quantum supremacy, but physicists think it’s a big deal.

And although we’re still decades from harnessing the full potential of quantum computers, and maybe years from even doing anything particularly useful at all, this achievement tells us that quantum computing is edging ever closer to those goals.