Seminarium: The surface code beyond Pauli noise
Naturvetenskap & IT
Ett seminarium med gästföreläsare Jan Behrends från Quantinuum (Cambridge, Storbritannien).
Föreläsning,
Seminarium
Ett seminarium med gästföreläsare Jan Behrends från Quantinuum (Cambridge, Storbritannien).
Jan Behrends, Quantinuum (Cambridge, UK)
Quantum information is famously fragile: interactions with the environment or imperfect control introduce errors that can rapidly destroy the underlying quantum states, rendering quantum computation impossible. Quantum error correction (QEC) offers a potential solution to this challenge via nonlocal encoding of information. However, most studies of its performance assume purely random errors (so-called Pauli noise), and are thus ignoring coherent errors due to, e.g., spurious gate rotations. In this talk, I will discuss generic errors beyond the Pauli noise approximation. I will introduce a mapping of the surface code, a leading QEC candidate, under coherent noise, taken as X- or Z-rotations, to a two-dimensional Ising model with complex couplings, and further to a 2D scattering network. As I will show, the critical rotation angle separating insulating and metallic phases in the scattering network corresponds to the error-correcting threshold. Finally, I will generalize these findings to more generic noise that interpolates between coherent and incoherent errors and briefly discuss results for coherent errors beyond X- or Z-rotations.