IBM Links 2 Quantum Processors With 99% Accuracy

A team at IBM Research has successfully linked two large superconducting quantum processors using four high-quality quantum links, achieving an average accuracy of 99% in transferring quantum states between the chips.

The links, approximately 80 cm (31-inch) long, are made of superconducting aluminum cable and were installed after both chips were already in place. The team used two 120-qubit Nighthawk R1 processors in the experiment, with the best link achieving an accuracy of 99.29% in transferring quantum states.

Two-qubit logic operations spanning both processors reached an average accuracy of 94.75%, and the team created entangled states shared across both processors using the linked setup. This breakthrough enables the creation of larger, more powerful quantum machines by interconnecting multiple processors.

## Why it matters The ability to link multiple quantum processors is crucial for the development of more powerful quantum computers. As quantum computers grow more ambitious, many researchers believe that building them in multiple interconnected parts is the best way forward. This modular design allows separate quantum processors to work together as one larger machine, but requires reliable links that can carry fragile quantum information without destroying it.

The IBM team's achievement is a significant step towards overcoming the challenges of building reliable links between superconducting processors. The links must be able to carry quantum information over distances of around a meter (3.3 feet) inside equipment chilled to just above absolute zero, without losing the signal or being affected by repeated warming and cooling of the system.

The work is detailed in a new paper published on the arXiv preprint server, and demonstrates the potential for creating larger, more powerful quantum machines by interconnecting multiple processors. This could lead to significant advances in fields such as cryptography, optimization, and simulation, and brings us closer to the development of practical quantum computers.

## What happens next The IBM team's breakthrough is an important step towards the development of more powerful quantum computers, but there is still much work to be done. The team will likely continue to refine their technique and work on scaling up the number of links and processors, with the goal of creating even larger and more powerful quantum machines. As the technology continues to advance, we can expect to see significant improvements in the field of quantum computing, and the potential for practical applications in a range of industries.