Google previews Bristlecone, its new quantum computing chip

Posted Mar 6, 2018 by James Walker
Google has announced a new quantum processor design. Known as Bristlecone, the chip is being designed as a "testbed" for quantum research. The company said it's "cautiously optimistic" that Bristlecone will allow it to achieve quantum supremacy.
Google Bristlecone
Google Bristlecone
Quantum supremacy
The project was detailed in a blog post from Google's Research team this week, after its unveiling at the annual American Physical Society meeting in Los Angeles. The chip is a 72-qubit quantum computing chip intended to be used by researchers at the forefront of the field. Specifically, Google wants to use Bristlecone to investigate ways to lower quantum computing error rates.
Error rates and scalability are two of the biggest limitations of current quantum research. The problems derive from the inherent instability of qubits, the quantum variant of regular computing bits. Noise in a system can substantially affect qubits and their states, which introduces errors into the computer. However, the error rate trends downwards as more qubits are added, so Bristlecone should help to mitigate some of the noise issues.
Previous Google quantum processor designs have relied on a 9-qubit architecture and obtained error rates around 0.6 percent. The company believes that "quantum supremacy" could be achieved by a chip that attains a 0.5 percent error rate. This would be equivalent to 49-qubits, so Google considers that Bristlecone could be the first quantum processor to outperform a regular supercomputer.
System harmony
Google recognises there are still significant challenges ahead. While Bristlecone is a compelling "proof-of-principle," its successful operation will require careful balancing of every component of the system. Google said that multiple iterations will be required before Bristlecone can demonstrate its ability to exceed the performance of classical computers.
"Operating a device such as Bristlecone at low system error requires harmony between a full stack of technology ranging from software and control electronics to the processor itself. Getting this right requires careful systems engineering over several iterations," said Google. "We are cautiously optimistic that quantum supremacy can be achieved with Bristlecone, and feel that learning to build and operate devices at this level of performance is an exciting challenge!"
Google Bristlecone quantum computing chip is being installed by Research Scientist at the Quantum AI...
Google Bristlecone quantum computing chip is being installed by Research Scientist at the Quantum AI Lab in Santa Barbara.
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Google's been working on quantum computers for several years but is no longer alone in the field. Research into quantum systems is gathering pace as more companies come close to finalising chip designs.
IBM and Microsoft are both working on quantum computers that could eventually be commercialised. IBM already has 50-qubit lab equipment and Microsoft has a 40-qubit cloud simulator. While Bristlecone may be the first chip to "cautiously" claim quantum supremacy, there's not yet a clear leader in the wider industry.