Practical Quantum Error Correction with the XZZX Code and Kerr-Cat Qubits
Andrew S. Darmawan, Benjamin J. Brown, Arne L. Grimsmo, David K. Tuckett, Shruti Puri · PRX Quantum · 2021
The development of robust architectures capable of large-scale fault-tolerant quantum computation should consider both their quantum error-correcting codes and the underlying physical qubits upon which they are built, in tandem.Following this design principle, we demonstrate remarkable error-correction performance by concatenating the XZZX surface code with Kerr-cat qubits.We contrast several variants of fault-tolerant systems undergoing different circuit-noise models that reflect the physics of Kerr-cat qubits.Our simulations show that our system is scalable below a threshold gate infidelity of p CX ∼ 6.5% within a physically reasonable parameter regime, where p CX is the infidelity of the noisiest gate of our system, the controlled-NOT gate.This threshold can be reached in a superconducting-circuit architecture with a Kerr nonlinearity of 10MHz, an approximately 6.25-photon cat qubit, single-photon lifetime of 64 μs, and a thermal photon population 8%.Such parameters are routinely achieved in superconducting circuits.