IQIM Postdoctoral and Graduate Student Seminar

Joint IQIM/AWS Seminar

Abstract: In this talk, I will discuss ongoing work to develop a technique for amplifying Wilson loops in a Z2 topologically ordered phase by applying local quantum error correction (QEC). Extending the QCNN framework for phase classification of Cong et al (2018), we interpret the application of local QEC as generating a real space RG flow towards the topological fixed point. In the Heisenberg picture, local QEC coarse-grains the bare Wilson loops, with the width of the new Wilson loops dependent on the range of the local QEC procedure. We present theoretical arguments that in the thermodynamic limit, if the coarse-grained Wilson loops go to one then this provides a sufficient condition for certification of topological order. Further, local error correction can also catch and correct local incoherent errors, and so the procedure can be applied to classify mixed states as well. We demonstrate the technique with numerical simulations of the toric code model as well as the recently proposed and observed dimer model on a ruby lattice [Verresen et al. (2020) and Semeghini et al. (2021)]. Finally, we present some results on experimental data from Semeghini et al.

Attendees joining in person must demonstrate that they comply with Caltech's vaccination requirements (Caltech ID or AWS ID required).

Amid the recent increase in COVID-19 cases on campus due to the arrival of the highly infectious BA.2 subvariant in Los Angeles County and a return to routine social activities, the Institute has reinstated its requirement that high-quality masks (surgical, N95s, KN95s, or KF95s) must be worn in all indoor locations on campus.