Reinforcement learning assisted recursive QAOA

EPJ Quantum Technology, vol. 11, pp. 6

Abstract

In recent years, variational quantum algorithms such as the Quantum Approximation Optimization Algorithm (QAOA) have gained popularity as they provide the hope of using NISQ devices to tackle hard combinatorial optimization problems. It is, however, known that at low depth, certain locality constraints of QAOA limit its performance. To go beyond these limitations, a non-local variant of QAOA, namely recursive QAOA (RQAOA), was proposed to improve the quality of approximate solutions. The RQAOA has been studied comparatively less than QAOA, and it is less understood, for instance, for what family of instances it may fail to provide high-quality solutions. However, as we are tackling NP-hard problems (specifically, the Ising spin model), it is expected that RQAOA does fail, raising the question of designing even better quantum algorithms for combinatorial optimization. In this spirit, we identify and analyze cases where (depth-1) RQAOA fails and, based on this, propose a reinforcement learning enhanced RQAOA variant (RL-RQAOA) that improves upon RQAOA. We show that the performance of RL-RQAOA improves over RQAOA: RL-RQAOA is strictly better on these identified instances where RQAOA underperforms and is similarly performing on instances where RQAOA is near-optimal. Our work exemplifies the potentially beneficial synergy between reinforcement learning and quantum (inspired) optimization in the design of new, even better heuristics for complex problems.

Authors 4

1. Yash J. Patel corresponding Aachen applied Quantum algorithms (aQa)

   Leiden University

   Affiliation as printed

   Applied Quantum Algorithms, Leiden University, Leiden, The Netherlands

   LIACS, Leiden University, Leiden, The Netherlands

2. Sofiène Jerbi corresponding

   Universität Innsbruck

   Affiliation as printed

   Institute for Theoretical Physics, University of Innsbruck, Innsbruck, Austria

3. Thomas Bäck Aachen

   Leiden University

   Affiliation as printed

   LIACS, Leiden University, Leiden, The Netherlands

4. Vedran Dunjko Aachen applied Quantum algorithms (aQa)

   Leiden University

   Affiliation as printed

   Applied Quantum Algorithms, Leiden University, Leiden, The Netherlands

   LIACS, Leiden University, Leiden, The Netherlands