Atom shows record 24 logical qubit quantum computer
Atom Computing n the US and Microsoft have entangled 24 logical qubits, setting a new world record. The two companies have also demonstrated error detection, correction, and computation with 28 logical qubits on Atom’s flagship systems.
The quantum computer uses neutral Ytterbium (Yb) atoms manipulated with lasers, creating the logical qubits from 112 physical qubits.
This is a key step for fault tolerant quantum computing to solve large computational problems beyond classical computing, and it requires the integration of multiple advanced technologies and quantum error correction algorithms to provide sufficient reliable computing resources in a sustainable way.
Compared to other qubit technologies, neutral atoms have several advantages including the ability to be tightly packed in arrays while being held in place by lasers, as well as the ability to be moved around so that they can interact with other atoms to enable all-to-all connectivity, says Krysta Svore, Technical Fellow and Vice President of advanced quantum development for Microsoft Azure Quantum.
Neutral atoms also have low susceptibility to noise and the high fidelities needed for quantum error correction to work. Due to their lack of charge, neutral atoms can be kept only microns (millionths of a meter) apart. The atomic arrays can accommodate large numbers of neutral atoms, each of which serves as a physical qubit, in a small amount of space, offering extensive scalability.
“The teams created 24 logical qubits and entangled them in a cat state, or Greenberger-Horne-Zeilinger (GHZ) state—this represents the highest number of entangled logical qubits on record. Entanglement of the qubits is evidenced by their error rates being significantly below the 50% threshold for entanglement,” she said.
When using neutral atoms as qubits and attempting to hold them in place with lasers, some atoms can still become lost, resulting in a loss of that qubit and its quantum information. Thus, the teams took steps to not only detect errors but also to detect and correct losses of neutral-atom qubits during experiments.
After creating logical qubits from neutral atoms and detecting errors and losses, the error rate in the logical qubits was 10.2%, which is 4.1 times better than the baseline physical error rate of 42%. When errors were detected and losses were detected and corrected, the error rate was 26.6%, which is 1.6 times better than the physical error rate.
This is the first demonstration on record of loss correction in a commercial neutral-atom system.
Twenty-eight logical qubits, created from 112 physical qubits, were used to perform successful computations based on the Bernstein-Vazirani algorithm. Furthermore, the logical qubits were able to produce a more accurate solution than the corresponding computation based on physical qubits. The ability to compute while detecting and correcting errors is a critical component to scaling to achieve scientific quantum advantage.
The second-generation systems have now demonstrated all of the key ingredients necessary for supporting quantum error correction, including large numbers of high-fidelity physical qubits which have all-to-all connectivity, long coherence times, and mid-circuit measurement with qubit reset and reuse.
“We are excited to show how our highly scalable neutral atom technology can be used to create large numbers of high-fidelity qubits that are a crucial part of Atom’s strategy to building fault tolerant quantum computers,” said Ben Bloom, Founder and Chief Executive Officer
Atom Computing is also announcing the demonstration of the highest two-qubit gate fidelity in a commercial neutral atom system. This is another important milestone in the company’s race to build fault-tolerant quantum computers, achieving state-of-the-art single-qubit and two-qubit gate fidelities in Atom’s second-generation systems.
In a preprint article on arXiv, the Atom team reported the measured performance of qubits contained in an optical tweezer array, with a 99.963(2)% single-qubit gate fidelity, and a 99.56(5)% two-qubit gate fidelity, demonstrating the best neutral-atom two-qubit gate fidelity in a commercial system.
Atom Computing recently announced that they have achieved 99.6% two-qubit gate fidelity, which represents the highest fidelity of neutral-atom qubits in a commercial system and unlocks the ability to perform meaningful error correction. Qubits with such low error rates and all-to-all connectivity are prime candidates for Microsoft’s custom qubit-virtualization system, which creates logical qubits and enables the detection and correction of errors while performing reliable quantum computation.
Microsoft’s Azure Quantum compute platform combines a qubit-virtualization system with quantum-processing units (QPUs) from several hardware partners including Photonic in Canada and IonQ in the US to create logical qubits by detecting and correcting the errors inherent in the QPU’s physical qubits, in turn enabling reliable quantum computation.
The qubit-virtualization system is a core component of the Azure Quantum compute platform and builds on Microsoft’s quantum error correction research, tailored to the underlying QPU.
“By co-designing the quantum computer with Atom Computing, we are enabling faster, more advanced, and more efficient quantum error correction as part of our qubit-virtualization system,” said Svore.
www.atom-computing.com; www.azure.microsoft.com
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