Adolfo del Campo
, Ikerbasque & DIPC
[Host: Israel Klich]
ABSTRACT:
The number of topological defects created in a system driven through a quantum phase transition exhibits a powerlaw scaling with the driving time. This universal scaling law is the key prediction of the KibbleZurek mechanism (KZM), and testing it using a hardwarebased quantum simulator is a coveted goal of quantum information science. Here we provide such a test using quantum annealing. Specifically, we report on extensive experimental tests of topological defect
formation via the onedimensional transversefield Ising model on two
different DWave quantum annealing devices. We find that the quantum simulator results can indeed be explained by the KZM for opensystem quantum dynamics with phaseflip errors, with certain quantitative deviations from the theory likely caused by factors such as random control errors and transient effects. In addition, we probe physics beyond the KZM by identifying signatures of universality in the distribution and cumulants of the number of kinks and their decay, and again find agreement with the quantum simulator results. This implies that the theoretical predictions of the generalized KZM theory, which assumes isolation from the environment, applies beyond its original scope to an open system.
We support this result by extensive numerical computations. To check whether an alternative, classical interpretation of these results is possible, we used the spinvector Monte Carlo model, a candidate classical description of the DWave device. We find that the degree of agreement with the experimental data from the DWave annealing devices is better for the KZM, a quantum theory, than for the classical spinvector Monte Carlo model, thus favoring a quantum description of the device. Our work provides an experimental test of quantum critical dynamics in an open quantum system, and paves the way to new directions in quantum simulation experiments.
Ref.:
Yuki Bando, Yuki Susa, Hiroki Oshiyama, Naokazu Shibata, Masayuki
Ohzeki, Fernando Javier GómezRuiz, Daniel A. Lidar, Sei Suzuki, Adolfo
del Campo, and Hidetoshi Nishimori, Phys. Rev. Research 2, 033369 (2020)

Condensed Matter Seminar
Thursday, November 5, 2020
9:30 AM
Online, Room via Zoom
Note special time.
Note special room.
Join Zoom Meeting:
https://virginia.zoom.us/my/israel.klich
