Quantum data are susceptible to decoherence induced by the environment and to errors in the hardware processing it. A future fault-tolerant quantum computer will use quantum error correction to actively protect against both. In the smallest error correction codes, the information in one logical qubit is encoded in a two-dimensional subspace of a larger Hilbert space of multiple physical qubits. For each code, a set of non-demolition multi-qubit measurements, termed stabilizers, can discretize and signal physical qubit errors without collapsing the encoded information. Here using a five-qubit superconducting processor, we realize the two parity measurements comprising the stabilizers of the three-qubit repetition code protecting one logical qubit from physical bit-flip errors. While increased physical qubit coherence times and shorter quantum error correction blocks are required to actively safeguard the quantum information, this demonstration is a critical step towards larger codes based on multiple parity measurements.
- Applied physics
- Quantum information
- Superconducting properties and materials
Ristè, D., Poletto, S., Huang, M-Z., Bruno, A., Vesterinen, V., Saira, O-P., & DiCarlo, L. (2015). Detecting bit-flip errors in a logical qubit using stabilizer measurements. Nature Communications, 6, . https://doi.org/10.1038/ncomms7983