After learning from the community, seeing how to run larger circuits, [we were able to] almost better define what it should be and rewrite the whole stack towards that," Gambetta said. The result is a dramatic speed-up. "Something that took 122 hours now is down to a couple of hours," he told Ars. This improvement not only benefits customers using the hardware but also reduces error occurrences in long calculations.
The researchers turned to a method where they intentionally amplified and then measured the processor's noise at different levels. These measurements are used to estimate a function that produces similar output to the actual measurements. That function can then have its noise set to zero to produce an estimate of what the processor would do without any noise at all, helping in error mitigation.
While it continues to work toward developing error-corrected qubits, IBM is focusing on error mitigation. This approach is computationally difficult, especially as the qubit count increases, but IBM has introduced optimizations. The importance of using functions to estimate output without noise is crucial, yet the risk of calculations becoming computationally intractable remains a challenge.
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