Quantum computing is based on the principles of the quantum theory to solve computational problems that are too complex for classical computers. These are seen as Sci-Fi rather than reality. But in 2019, computer scientists at *Google* claim to have reached *quantum supremacy*. According to Chinese researchers, they claim to have reached quantum supremacy way ahead of* *any classical computers.

**Related media: Demonstrating Quantum Supremacy**

**What’s Quantum Supremacy?**

Quantum supremacy refers to the level of computational power that a *quantum computer* is capable of that will take *classical computers* like forever to solve. This is also known as *quantum advantage* or *quantum primacy*. Quantum computers are highly advanced in computational processing. Classical computing — the computers we still use today — uses binary data for processing. What this means is that, they can only switch between *on* and *off* state. In other words, they process data in *1s* and *0s*— bits.

Quantum computing, on the other hand, uses quantum bits (also known as *qubits*). This is a type of computation that harness the collective properties of *quantum mechanics* — such as superposition, interference, and entanglement — to perform calculations. What this means is that, a quantum computer is capable of solving mathematical problems that are far beyond any classical computer today. By contrast, a quantum computer could solve a problem that could take thousands of years for classical computers to solve in a matter of seconds.

In 2019, engineers at *Google* announced that its *Sycamore* quantum computer had achieved quantum supremacy. They claimed that *Sycamore* solved a mathematical problem in just three minutes that would have taken the world’s supercomputer as at the time 10,000 years. This term was created to describe any computer that had such incredible computational power.

**The Rise To Supremacy**

In July 2021, researchers from the University of Science and Technology of China announced that it had surpassed the quantum supremacy of *Google’s Sycamore*. This was achieved by two teams of researchers with different quantum computers. The details of their breakthrough was published on the peer-reviewed journal *Physical Review Letters*. For years, several teams working with several computers claim to have reach supremacy, but have been met with skepticism about whether the right algorithm was used.

Both teams claim that their quantum computers had a little margin of error. Their demonstration was conducted at the *Hefei National Laboratory for Physical Sciences* at the university, and was led by physicist Jian-Wei Pan, who’s an expert in quantum entanglement. According to Pan and his team, their computer solved a problem a little over an hour that would take the world’s most powerful classical supercomputer eight years. They even claim it could be capable of performing exponentially higher.

This problem — now a benchmark in quantum computing — involves simulating a *quantum circuit*, and sampling random numbers from its output. But the problem increases exponentially in complexity as more qubits are added to the circuit being modeled. What this means is that, the level of complexity will ever increase with classical computing, bringing computation to a grinding halt.

**Double Testing For Quantum Supremacy**

Both teams experimented with two efforts. First, they used *photonics* in building their computer. And to tackle the problem, the team analyzed the output by using *Gaussian boson* sampling. This was output from a 144-mode interferometer. In this case, there could be 1043 possible outcomes. But the researchers claim their computer was capable of sampling 1023 times faster than a supercomputer, which, they further claim, is quantum supremacy.

Next, they created a superconductor-based computer that was capable of using 66 qubits for computation. However, only 56 qubits were used, but researchers were convinced that their computer was capable of estimating sample calculations up to 1000 times faster than supercomputers. This, they claim, is an achievement worthy of supremacy. Both efforts sought to build a quantum computer capable of computing the output probabilities of quantum circuits. This is what classical computers are still limited to, unless quantum computers.

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*Written by:* *Nana Kwadwo,** Thu, Jan 13, 2022.*