Exploring More-Coherent Quantum Annealing

TL;DR

This paper reports on recent experimental progress in improving qubit coherence for quantum annealing, focusing on flux qubits, to better understand and enhance QA's potential as a computing resource.

Contribution

It introduces new techniques for crosstalk calibration and qubit readout in flux qubits, advancing the engineering of high-coherence QA-capable qubits.

Findings

Preliminary measurements show progress in qubit coherence.

Techniques developed for crosstalk calibration improve measurement accuracy.

Work lays groundwork for exploring QA physics and viability.

Abstract

In the quest to reboot computing, quantum annealing (QA) is an interesting candidate for a new capability. While it has not demonstrated an advantage over classical computing on a real-world application, many important regions of the QA design space have yet to be explored. In IARPA's Quantum Enhanced Optimization (QEO) program, we have opened some new lines of inquiry to get to the heart of QA, and are designing testbed superconducting circuits and conducting key experiments. In this paper, we discuss recent experimental progress related to one of the key design dimensions: qubit coherence. Using MIT Lincoln Laboratory's qubit fabrication process and extending recent progress in flux qubits, we are implementing and measuring QA-capable flux qubits. Achieving high coherence in a QA context presents significant new engineering challenges. We report on techniques and preliminary measurement results addressing two of the challenges: crosstalk calibration and qubit readout. This groundwork enables exploration of other promising features and provides a path to understanding the physics and the viability of quantum annealing as a computing resource.