正方格子上竞争反铁磁性与d波超导电性的Floquet工程
Floquet engineering of competing antiferromagnetism and $d$-wave superconductivity on the square lattice
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- Department of Physics, Harvard University（哈佛大学物理系）
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中文总结 AI 辅助
本研究提出受驱动的Lieb-Hubbard量子模拟器，通过Floquet工程实现正方格子上独立可调的键吸引与 onsite 排斥相互作用，揭示反铁磁与d波超导相的竞争关系，为量子模拟协议设计提供新方向。
中文摘要 AI 辅助
我们提出一种受驱动的Lieb-Hubbard量子模拟器，其准热动力学可实现正方格子上的自旋1/2费米子模型，该模型具有独立可调的 onsite 排斥相互作用与键吸引相互作用。周期性调制Lieb格子的格点（$d$）轨道与键（$p$）轨道之间的电荷转移偏移，可使$p$轨道的双占据态在能量上接近$d$轨道中的一对粒子，同时保持所有$p$轨道的单占据态非共振，从而在Lieb格子的键位点上构建出合成的“负$U$”中心。随后通过两次可控消除，在简化的仅含$d$轨道的正方格子模型中产生紧凑的键吸引作用，尽管$p$轨道中存在微观排斥作用。所得的相互作用$J$可独立于$d$轨道的Hubbard排斥$U_d$进行调节，而光子辅助路径间的干涉则可实现中间耦合区，其中$J$与$U_d$均与有效 hopping 相当。在半填充时，该耦合区的平均场计算发现相邻的反铁磁相与d波超导相，以及狭窄的共存区域，表明这些序之间存在密切竞争。我们讨论了将该形式构造转化为光晶格协议所需的分支制备、准热及高能带条件。更广泛地说，我们的工作确定了Floquet系统与电子-声子问题之间的结构相似性，这可能为新型量子模拟协议的设计提供指导。
英文摘要
We propose a driven Lieb--Hubbard quantum simulator whose prethermal dynamics realize a square-lattice spin-1/2 fermion model with independently tunable repulsive on-site and attractive bond interactions. Periodically modulating the charge-transfer offset between the site ($d$) and bond ($p$) orbitals of the Lieb lattice brings a $p$-orbital doublon energetically close to a pair in the $d$ manifold while keeping all $p$-orbital singlons off resonance, thereby creating a synthetic ``negative-$U$'' center on a Lieb-lattice bond site. Two controlled eliminations then generate a compact bond attraction in the reduced $d$-only model on the square lattice, despite the microscopic repulsion in the $p$ orbital. The resulting interaction $J$ is tunable independently of the Hubbard repulsion $U_d$ on the $d$ orbitals, while interference between photon-assisted paths provides access to an intermediate-coupling regime in which $J$ and $U_d$ are both comparable to the effective hopping. At half filling, a mean-field calculation in this regime finds adjacent antiferromagnetic and $d$-wave superconducting phases, as well as narrow coexistence regions, suggesting close competition between these orders. We discuss the branch-preparation, prethermal, and higher-band conditions required to translate the formal construction into an optical-lattice protocol. More broadly, our work identifies a structural similarity between Floquet systems and electron-phonon problems that may guide the design of novel quantum-simulation protocols.
