On Monday, IBM announced that it has produced two quantum computer systems according to the roadmap planned for release in 2023. One is based on a chip named Condor, which is the largest transmon-based quantum processor ever released, with a working capacity of 1121 qubits. The second is based on a mix of three Heron chips, each containing 133 qubits. Smaller chips such as Heron and its successor Flamingo will play a crucial role in IBM’s quantum roadmap – which also received a major update today.
Evolving the Qubit and Logical Qubit
Every aspect of working with qubits is prone to errors. Setting their initial state, maintaining that state, performing operations, and reading the state can lead to errors that prevent quantum algorithms from producing useful results. Therefore, the main focus of every company producing quantum devices has been to reduce these errors, and significant progress has been made in this regard.
There are some indications that these advancements have now brought us to the point where some simpler quantum algorithms can be executed on existing devices. It is likely that this potential will expand to include more algorithms thanks to improvements we can expect in the coming years.
Logical Qubit and Gates
Gambita stated that the company has followed two approaches to make its devices ready. One aspect of that is developing the ability to manufacture high-quality qubits in large numbers consistently. He mentioned that Condor, which has over 1000 qubits, is proof that the company is doing well in this regard. “It has 50 percent smaller qubits,” Gambita told Ars. “The yield is very high – we got nearly 100 percent yield.”
The second aspect that IBM has worked on is reducing the errors that occur when executing operations on individual qubits or pairs of qubits. These operations, known as gates, can be prone to errors themselves. Changing the state of a qubit can produce weak signals that can leak into neighboring qubits, a phenomenon known as crosstalk. The Heron, the smaller of the new processors, represents a four-year effort to improve gate performance. “It’s a beautiful device,” Gambita said. “It’s five times better than previous devices, and the errors are much lower, and crosstalk isn’t measurable anymore.”
Many of the improvements stem from the introduction of tunable connectors to the qubits, a shift from the fixed-frequency devices the company used previously. This has increased the speed of all gate operations, with some seeing a tenfold increase. The less time spent doing anything with a qubit, the lower the chance for errors to occur.
Many of these improvements have been tested across several iterations of the Eagle chip, which was first introduced in 2021. The company’s new roadmap will see the release of an improved Heron chip featuring 133 qubits next year, which will enable 5000 gate operations. This will be followed by several iterations of the Flamingo processor featuring 156 qubits next year, which will increase gate operations to 15000 by 2028.
These chips will also be linked together in larger processors like Crossbill and Kookaburra, which also appear in IBM’s roadmap (for example, seven Flamingos can be linked together to create a processor with a qubit count similar to the current Condor). The focus here will be on testing various means of connecting qubits, whether within chips or between them.
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