Seminar: The surface code beyond Pauli noise
Science and Information Technology
A seminar with guest speaker Jan Behrends från Quantinuum (Cambridge, Storbritannien).
Lecture,
Seminar
A seminar with guest speaker 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.