AI 中文总结
本文理论发展量子比特光谱技术，可探测铁磁体的量子压缩磁振子态叠加，分析了多压缩福克态叠加激发态的探测难点及低振幅相干压缩磁振子态的权衡关系，为相关探测提供基础与设计方程。
AI 中文摘要
有序磁体具有本征压缩基态和磁振子激发，其特征为自旋与非经典磁振子数组分之间的纠缠。近期已有研究通过利用量子比特与磁振子模式通过直接色散相互作用耦合，证明了一种探测这些非经典磁基态所对应的非本征模式磁振子数态叠加的方法。本文在理论上进一步发展了该量子比特光谱技术，明确了其用于探测激发态所对应的量子叠加态的能力与局限。我们证明该光谱技术可自然地揭示各种量子化压缩磁振子数态所对应的叠加态。然而，由多个压缩福克态叠加构成的激发态，由于可能的跃迁数量过多，导致量子比特光谱中的峰数量增多，从而使探测难度增大，这需要具有更窄线宽的量子比特。基于同样的思路，我们在理论上对低振幅相干压缩磁振子态的量子比特光谱进行了分析，探讨了因多跃迁导致的频率拥挤与峰线宽之间的权衡关系。本研究为利用高品质量子比特探测磁性系统中自旋激发的复合特性奠定了基础并提供了设计方程。
英文摘要
Ordered magnets harbor intrinsically squeezed ground states and magnonic excitations characterized by entanglement between spins and nonclassical magnon number composition. A pathway to detecting the superpositions of noneigenmode magnon number states underlying these nonclassical magnetic ground states has recently been demonstrated by utilizing a qubit coupled to the magnon mode via a direct dispersive interaction. Here, we theoretically develop this qubit spectroscopy further delineating the capabilities and limitations of this qubit spectroscopy for sensing the quantum superpositions that underlie the excited states. We demonstrate that the spectroscopy lends itself naturally to unraveling the superpositions that underlie the various quantized squeezed-magnon number states. However, excited states comprising superpositions of multiple squeezed Fock states become increasingly hard due to the large number of possible transitions, and resulting peaks, in the qubit spectroscopy thereby requiring qubits with narrower linewidths. Along the same lines, we theoretically demonstrate the qubit spectroscopy of a low amplitude coherent squeezed-magnon state analyzing the tradeoff between frequency crowding due to multiple transitions and peak linewidths. Our work lays the groundwork and design equations for deploying high-quality qubits towards sensing the composite nature of spin excitations in magnetic systems.
