Quantum computers work differently from classical computers we work on today. They can easily tackle computational problems that may be tough for the classical computer by exploiting the principles of quantum mechanics.
Quantum computers don’t appear as if desktops or laptops that we associate the word ‘computer’ with. Instead, they resemble the air-conditioned server rooms of many offices or the stacks of central processing units from desktops of yore that are connected by ungainly tangled wires and heaped in freezing rooms.
Working principle of Quantum computers
Quantum computers compute in ‘qubits’ (or quantum bits). They exploit the properties of quantum physics, the science that governs how matter behaves on the atomic scale. In this scheme of things, processors are a 1 and a 0 simultaneously. This state is known as quantum superposition.
While this accelerates the speed of computation, a machine with less than a 100 qubits can solve problems with a lot of data that are even theoretically beyond the capabilities of the most powerful supercomputers. Because of quantum superposition, a quantum computer — if it works to plan — can imitate several classical computers working in parallel.
“The ideas governing quantum computers are around since the 1990s but actual machines are around since 2011. Those are most notably build by Canadian company D-Wave Systems.”
Quantum supremacy is the moment a quantum computer performs calculations that a classical computer simply can’t keep up with. It involves both the engineering task of building a powerful quantum computer and the computational complexity-theoretic task of finding a problem that a quantum computer can solve. Apart from these, it has a super polynomial speedup over the best known or possible classical algorithm for that task.
How Google has achieved this?
Google made a huge disclosure on October 23, 2019, when it announced that it had reached “quantum supremacy”.
Google used a 53-qubit processor to get a sequence of many numbers. Though these numbers appeared randomly generated, they meet an algorithm generated by Google. A classical supercomputer checked some of these values and they were correct. Google’s quantum computer is Sycamore claims ‘supremacy’. Because it did the task in 200 seconds that would have taken a supercomputer 10,000 years to complete.
An artist’s drawing of Google’s quantum computer chip, called Sycamore, and its surrounding hardware. Forest Stearns, Google AI Quantum Artist in Residence.