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The team restored error suppression in a stand-in test for logic gates by removing defective parts. The larger distance-5 code beat a distance-3 code only after the team discarded runs affected by leakage, and only in one basis.
Researchers lengthened a surface code in one direction on IBM Heron processors and reduced the matching type of logical error. With a measure that combined both error types, the team found no subthreshold scaling on its best-performing chip.
IBM researchers discarded runs that failed error checks on 49 physical qubits of a Heron processor, then applied error cancellation to the remaining noise. They inferred a sampling cost of 1,359 at six time steps, versus 85,545 without the checks.
A Sandia-led team scored Google, IBM, and Quantinuum processors and a logical-qubit machine on one scale. Helios-1 led at 1,504 without discarded runs, against about 250 million that the authors calculated for factoring RSA-2048.
Fujitsu put tin-vacancy centers into photonic chips that run at about 1.55 kelvin and, in testing, can be used through its software platform. It gave no qubit count, gate fidelity, coherence time, or entanglement rate.
The Novo Nordisk Foundation says the Copenhagen plant will offer wafer fabrication to quantum vendors worldwide on commercial terms. The partners named no customers, qubit type, production volume, or cost.
Error-correction, key-distribution, and algorithmic decoders are three of several jobs that share one name. Only the first runs against a machine's clock, where its speed and accuracy affect the clock rate and qubit cost of fault-tolerant designs.
IBM's two joined cryogenic cells reached 4 kelvin in under five days with no processors inside. News outlets reported a temperature under simulated load and a chip-link fidelity figure that IBM did not include in its release or technical blog.
Researchers have measured quantum illumination's advantage over classical radar only with targets about a meter away or inside a refrigerator. Chinese state media have reported 100-kilometer-class detection for a single-photon radar, a different technique, without test data.
Five physicists calculated that an Andreev qubit in a superposition should produce an oscillating supercurrent with no applied voltage. In simulations described in their preprint, they read one test state from that current with infidelities of 0.15% to 0.48%.
