New design removes 98.4% of qubit leakage during measurement

Researchers at QuTech, Delft University of Technology have achieved 98.4% removal of qubit leakage during measurement, a critical step toward building more stable quantum computers. This leakage, where quantum information escapes the computational state, introduces errors that limit the effectiveness of quantum error correction. The team integrated directly into the qubit measurement process, returning the qubit to its computational subspace without adding time to the operation. This work combines this enhanced measurement with neural-network decoding to suppress logical error rates in quantum error correction experiments. This leakage, specifically the excitation of a transmon qubit to a second excited state, introduces correlated errors that hinder the effectiveness of quantum error…