Quantum computers could fundamentally change our understanding of problem solving and calculations in the near future. However, the technology still faces a crucial hurdle – the error-proneness of quantum bits, which are the central building blocks of quantum computers. Google has now reached a significant milestone with its latest success in quantum error correction.
Researchers at Google’s Quantum Artificial Intelligence Lab have managed to combine 97 error-prone quantum bits into one logical quantum bit that has a significantly lower error rate. This is an important step on the way to error-tolerant quantum computers that could perform complex calculations in the future.
Challenges of quantum error correction
The biggest challenge for quantum computers is the high probability of errors during computing operations. In current systems, the probability of error is between 0.01 and 1 per cent, depending on the operation. As quantum computers potentially require thousands of calculation steps, this means that the possibility of errors increases exponentially. Without effective error correction, the advantages of quantum computers would be almost impossible to utilise in practice.
The Google researchers developed a method in which quantum information is distributed across several quantum bits. Measurement bits ensure the stability of the states without directly changing the information. This redundant approach, which is also used in classical computers, led to the formation of a more robust logical quantum bit.
A decisive advance – but not yet the goal
Google was able to achieve a critical error threshold by reducing the error rate of a 97-qubit quantum bit system to half that of a 49-qubit system. This progress is highly rated by experts and can be compared to the groundbreaking results of 2019, when Google demonstrated for the first time that quantum computers can outperform conventional computers in certain tasks.
Despite this promising development, quantum research still faces huge challenges. The next step is to perform basic computing operations with the stabilised logical quantum bits. In the long term, these stable bits will be used to enable complex and fault-tolerant calculations.
Fault-tolerant quantum computers and their application
Although the progress made so far is impressive, there is still a long way to go before quantum computers are able to solve really complicated problems. It is estimated that around 1457 physical quantum bits are needed to achieve an error rate of 1 in 1,000,000 – a minimum requirement for solving simple problems.
For complex challenges such as breaking modern encryption methods, even thousands of logical quantum bits are required. Therefore, further progress in quantum error correction and more efficient algorithms are urgently needed to reduce the required number of physical quantum bits.
A clear path ahead
The current results from Google and other research groups form a solid basis for the development of the quantum computers of the future. While many technical hurdles remain, recent advances are making the goal of a powerful, fault-tolerant quantum computer more tangible. Whether and how the technology will become established in practice remains to be seen, but the outlook is now clearer than ever before.
