标题： 具有厄米子空间的分子自旋超精细能级中完全吸收的观测 显示英文标题

标题： Observation of Perfect Absorption in Hyperfine Levels of Molecular Spins with Hermitian Subspaces

摘要： 理想的有效的宇称-时间(PT)对称性可以在一个被动的开放系统中通过精确平衡供能和吸收过程来实现。 这样的 PT-对称系统显示出厄米子空间，这使得辐射能够被完全吸收（PA），即所有入射能量都被系统吸收。 在这项工作中，我们考虑了一个通过耦合分子自旋中心与一个工作在毫开尔文温度和少光子功率级别的平面微波谐振腔而获得的被动开放量子系统。 我们实验演示了即使在没有PT-对称性的情况下，也可以通过利用自旋失谐来控制极化子模式的光子和自旋成分，从而实现厄米子空间和因此的PA。 这样，供能和损耗率之间的所需平衡就可以有效地恢复。 我们展示了厄米子空间影响了腔 QED系统的相干光谱的整体特征，并显著扩大了在开放量子系统中探索非厄米效应的可能性。 最后，我们讨论了厄米子空间如何可能被用于开发具有高调制深度的高效开关和调制器，适用于广泛的光谱范围。 显示英文摘要

摘要： Ideal effective parity-time (PT)-symmetry can be achieved in a passive open system by accurately balancing feeding and absorption processes. Such PT-symmetric systems display Hermitian subspaces which enable perfect absorption (PA) of radiation, i.e., all the incoming energy is absorbed by the system. In this work, we consider a passive open quantum system obtained by coupling molecular spin centers to a planar microwave resonator operating at milliKelvin temperatures and at few-photon power level. We experimentally demonstrate that Hermitian subspaces and thus PA can be implemented even in the absence of PT-symmetry, by exploiting the spin detuning to control the photon and spin content of a polariton mode. In such a way, the required balance between the feeding and the loss rates is effectively recovered. We show that Hermitian subspaces influence the overall aspect of coherent spectra of cavity QED systems and significantly enlarge the possibility to explore non-Hermitian effects in open quantum systems. We finally discuss how Hermitian subspaces can be potentially exploited for the development of efficient switches and modulators with high modulation depths over a broad spectral range.