Southwest Quantum Information and Technology

The impact of errors in the operation of a small, highly-accurate quantum simulator

Presenting Author: Nathan Lysne, University of Arizona
Contributing Author(s): Kevin Kuper, Pablo Poggi, Ivan Deutsch, Poul Jessen

Quantum simulation is widely considered a promising application of NISQ processors. Recently, these devices have reached a scale where their operation cannot be validated by direct comparison against classical computation. At the same time, the accuracy of a quantum simulation running on NISQ-era hardware is likely to degrade after only a few time steps, especially when applied to complex systems whose dynamics exhibit quantum chaos and hypersensitivity to errors. This leaves open the question whether the output of a non-trivial quantum simulation on such a device will ever be useful. We have developed a small, highly-accurate, and fully programmable quantum processor capable of simulating >100 time steps with an average fidelity >0.99 per time step. Using this as our test bed, we investigate the interplay between native and Trotter errors in quantum simulation. Our preliminary findings shows that the optimal Trotter step is not the smallest possible, but instead represents a device-dependent compromise between Trotter and native errors. We also examine how sensitive different observables are to the presence of native errors and find quantitative differences based on their structure. Our results support the conjecture that “bulk” observables, (e. g., total magnetization) can be robust in the presence of errors, while observables tied to a specific quantum state (e. g., the fidelity) are not.

(Session : from 5:00pm - 7:00pm)