近日，美国加州大学的Alp Sipahigil及其研究团队取得一项新进展。经过不懈努力，他们揭示声子带隙中超导量子比特的非马尔可夫动力学。相关研究成果已于2025年1月7日在国际知名学术期刊《自然—物理学》上发表。

在这项工作中，该研究团队利用声子学来设计量子比特与周围二能级系统之间的相互作用。研究人员在一种具有声子带隙的超材料上制造了超导量子比特，该材料能抑制由二能级系统介导的声子发射。经过声子工程处理的二能级系统浴显示出更长的寿命，并影响了量子比特的热化动力学。在声子带隙内，研究人员观察到了量子比特的非马尔可夫行为。结合量子比特的微型化，该研究方法有望显著延长量子比特的弛豫时间。

据悉，在量子计算机中，减少退相干能迅速降低从物理量子比特构建逻辑量子比特所需的开销。在固态系统中，一类被称为二能级系统的缺陷是退相干的主要来源。目前，超导量子比特实验通过增大器件尺寸来减少由二能级系统引起的耗散。然而，这种方法仅提供部分保护，并且需要在量子比特尺寸和耗散之间做出权衡。

附：英文原文

Title: Non-Markovian dynamics of a superconducting qubit in a phononic bandgap

Author: Odeh, Mutasem, Godeneli, Kadircan, Li, Eric, Tangirala, Rohin, Zhou, Haoxin, Zhang, Xueyue, Zhang, Zi-Huai, Sipahigil, Alp

Issue&Volume: 2025-01-07

Abstract: Reducing decoherence in quantum computers rapidly decreases the overhead needed to construct a logical qubit from physical qubits. In solid-state systems, a class of defects known as two-level systems is a major source of decoherence. Currently, superconducting qubit experiments reduce dissipation due to the two-level systems by using large device dimensions. However, this approach only provides partial protection and results in a trade-off between qubit size and dissipation. In this work, we instead engineer the interactions between a qubit and the surrounding two-level systems using phononics. We fabricate a superconducting qubit on a phononic-bandgap metamaterial that suppresses phonon emission mediated by the two-level systems. The phonon-engineered bath of two-level systems shows increased lifetime and affects the thermalization dynamics of the qubit. Within the phononic bandgap, we observe the emergence of a non-Markovian qubit behaviour. Combined with qubit miniaturization, our approach could substantially extend the qubit relaxation times.

DOI: 10.1038/s41567-024-02740-5

Source: https://www.nature.com/articles/s41567-024-02740-5