A Qubit

Hot Qubits and Goldilocks Ions

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+  Due to their sensitivity, hundreds of thousands, perhaps even millions of qubits are required to produce low-error quantum set-ups that would revolutionize computing. Today, even the most sophisticated systems, such as Google’s Sycamore and IBM’s Raleigh, have just a few tens of qubits.

+  Following are three new approaches being pursued that could edge us closer to an actual quantum reality.

+  Faster operations with giant atomic ions

+  Speed also impacts scalability. As in classical computing, logic gates and circuits are bedrocks of quantum computing. To be useful, qubits need to implement gate operations at high speed, but weak interactions slow the process down.

+  Researchers at the Universities of Nottingham and Stockholm have developed an approach that uses trapped Rydberg ions to create faster quantum gate operations. The system combines the strong dipolar interaction of Rydberg atoms with the quantum benefits of trapped ions— ions suspended in a trap— which have low error rates and can be accurately controlled.

+  Hot qubits for cooler computing

+  Along with collaborators from Canada’s Université de Sherbrooke, Finland’s Aalto University, Japan’s Keio University, and the Canadian Institute for Advanced Research, the researchers produced a proof-of-concept quantum processor unit cell using silicon qubits that operates at 1.5 Kelvin —15 times hotter than most other qubits.

+  In practical terms, says Dzurak, this equates to cheaper, simpler cooling systems. “You can now imagine having millions of these silicon qubits on a chip and integrated with the control electronics, so it really solves this key issue of scalability up to millions of qubits.”

+  A Goldilocks ion for error reduction

+  Researchers at University of California, Los Angeles (UCLA) have developed a new trapped-ion qubit that improves the fidelity, or accuracy, of quantum computations.

+  As we move into the Noisy Intermediate-Scale Quantum (NISQ) era and see the development of 50+ qubit computers, errors in the preparation and measurement of qubits remain a major challenge.

+  “In general, the field is striving to build a gate-based quantum computer where error correction can be implemented at or below the fault-tolerant threshold, i.e., applying error correction improves accuracy of the computation,” says Justin Christensen, a researcher at UCLA’s Hudson Lab.

Source:  COMMUNICATIONS of the ACM.  Karen Emslie,  Hot Qubits and Goldilocks Ions…

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