Newly identified correlated errors in superconducting qubits could limit the performance of error-correction schemes needed for a practical quantum computer.
Building a working quantum computer is challenging because its basic components, qubits, are highly sensitive to environmental disturbances that compromise computation. Whereas classical bits can only undergo bit-flip errors that change 0 to 1 or vice versa, qubits also suffer from so-called phase errors that degrade the fundamental quantum interference effects essential for quantum computation. Joining several good, but not perfect, physical qubits into a logical qubit makes quantum error correction possible (see Research News: Cracking the Challenge of Quantum Error Correction). But that strategy can fail if too many qubits become faulty at the same time. In one leading hardware platform, superconducting circuits, such correlated qubit errors are typically triggered every few tens of seconds when ionizing radiation from the environment deposits energy into the chip hosting the circuits.








