“Researchers at QuTech—a collaboration between the TU Delft and TNO—have reached a milestone in quantum error correction. They have integrated high-fidelity operations on encoded quantum data with a scalable scheme for repeated data stabilization. The researchers report their findings in the December issue of Nature Physics.”
“‘Two capabilities will distinguish an error corrected quantum computer from present-day noisy intermediate-scale quantum (NISQ) processors’, says Prof Leonardo DiCarlo of QuTech. ‘First, it will process quantum information encoded in logical qubits rather than in physical qubits (each logical qubit consisting of many physical qubits). Second, it will use quantum parity checks interleaved with computation steps to identify and correct errors occurring in the physical qubits, safeguarding the encoded information as it is being processed.’ According to theory, the logical error rate can be exponentially suppressed provided that the incidence of physical errors is below a threshold and the circuits for logical operations and stabilization are fault tolerant.”
“The basic idea thus is that if you increase the redundancy and use more and more qubits to encode data, the net error goes down. The researchers at TU Delft, together with colleagues at TNO, have now realized a major step toward this goal, realizing a logical qubit consisting of seven physical qubits (superconducting transmons). ‘We show that we can do all the operations required for computation with the encoded information. This integration of high-fidelity logical operations with a scalable scheme for repeated stabilization is a key step in quantum error correction’, says Prof Barbara Terhal, also of QuTech.”