Automated Discovery of Autonomous Quantum Error Correction Schemes

作者：Zhaoyou Wang, Taha Rajabzadeh, Nathan Lee, Amir H. Safavi‐Naeini · 发表于：PRX Quantum · 年份：2022 · DOI：10.1103/prxquantum.3.020302 · 被引用次数：22 · 研究领域：Quantum Computing Algorithms and Architecture、Quantum Information and Cryptography、Advancements in Semiconductor Devices and Circuit Design

We can encode a qubit in the energy levels of a quantum system.Relaxation and other dissipation processes lead to decay of the fidelity of this stored information.Is it possible to preserve the quantum information for a longer time by introducing additional drives and dissipation?The existence of autonomous quantum error correcting codes answers this question in the positive.Nonetheless, discovering these codes for a real physical system, i.e., finding the encoding and the associated driving fields and bath couplings, remains a challenge that has required intuition and inspiration to overcome.In this work, we develop and demonstrate a computational approach based on adjoint optimization for discovering autonomous quantum error correcting codes given a Hamiltonian description of a physical system.We implement an optimizer that searches for a logical subspace and control parameters to better preserve quantum information.We demonstrate our method on a system of a harmonic oscillator coupled to a lossy qubit, and find that varying the Hamiltonian distance in Fock space-a proxy for the control hardware complexity-leads to discovery of different and new error correcting schemes.We discover what we call the √ 3 code, realizable with a Hamiltonian distance d = 2, and propose a hardware-efficient implementation based on superconducting circuits.