Quantum supremacy refers to quantum computers being able to solve a problem that a classical computer cannot. Google achieved this feat on their quantum computer based on Google’s new 54-qubit processor, named “Sycamore” that is comprised of fast, high-fidelity quantum logic gates in order to perform the benchmark testing. The machine performed the target computation in 200 seconds, and from measurements in the experiment it was determined that it would take the world’s fastest supercomputer 10,000 years to produce a similar output.
Principle of Quantum Computing
So quantum computers work on exploiting the principles of quantum mechanics, Conventional computers process information in ‘bits’ or 1s and 0s, following classical physics under which our computers can process a ‘1’ or a ‘0’ at a time. The world’s most powerful super computer today can juggle 148,000 trillion operations in a second and requires about 9000 IBM CPUs connected in a particular combination to achieve this feat. Quantum computers compute in ‘qubits’ (or quantum bits). In this scheme of things, processors can be a 1 and a 0 simultaneously, a state called quantum superposition. Because of quantum superposition, a quantum computer can mimic several classical computers working in parallel.
The success of the quantum supremacy experiment was due to improved two-qubit gates with enhanced parallelism that reliably achieve record performance, even when operating many gates simultaneously. This kind of performance was achieved using a new type of control knob that is able to turn off interactions between neighboring qubits. This greatly reduces the errors in such a multi-connected qubit system. Further performance gains were achieved by optimizing the chip design to lower crosstalk, and by developing new control calibrations that avoid qubit defects.
The SYCAMORE
The quantum supremacy experiment was run on a fully programmable 54-qubit processor named “Sycamore” developed by Google.
Each qubit is about 0.2 millimeter across, big enough to be visible through an ordinary microscope. But chilled and hidden away from external influences, each becomes a superconductor that lets electrons flow freely, acting as if it were a single atom so that the laws of quantum mechanics scale up to dictate its behavior. The Sycamore is comprised of a two-dimensional grid where each qubit is connected to four other qubits. As a consequence, the chip has enough connectivity that the qubit states quickly interact throughout the entire processor, making the overall state impossible to emulate efficiently with a classical computer.
For example, a pair of bits can store just one of four possible combinations of states (00, 01, 10 or 11) at any given time. A pair of qubits can store all four combinations simultaneously, because each qubit represents both values (0 and 1) at the same time. If you add more qubits, your computer's power grows exponentially. Three qubits store eight combinations, four qubits store 16, and so on. Google's new computer with 54 qubits can store 253values, or more than 10,000,000,000,000,000 (10 quadrillion) combinations. This number gets even more impressive when another fundamental and equally bizarre property of quantum mechanics enters the show: entangled states.
The Sycamore based quantum computer is fully programmable and can run general-purpose quantum algorithms. Since achieving quantum supremacy results, the team has already been working on near-term applications, including quantum physics simulation and quantum chemistry, as well as new applications in generative machine learning, among other areas.
"The first plane flew only for 12 seconds, and so there is no practical application of that. But it showed the possibility that a plane could fly. Useful quantum machines are many years away, the technical hurdles are huge but this is just the beginning”
An informative write up indeed for the uninitiated ones into quantum computers
Truly amazing, the feat that our quantam computers can achieve. Well written article. Thanks for the details.