Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states
Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states
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DOI：
10.1038/s41534-017-0041-3
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发表时间：
2017-09-28
影响因子：
7.6
通讯作者：
Kay, Christopher W. M.
中科院分区：
文献类型：
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作者：
Breeze, Jonathan D.;Salvadori, Enrico;Kay, Christopher W. M.
强耦合机制对于在短于其寿命的时间尺度上不同量子系统中的状态之间的激发的有效转移至关重要。单自旋与微波光子的耦合非常弱，但可以通过减小腔的磁模式体积来增加局部态密度来增强。在实践中，很难同时实现小腔模体积和低腔衰减率，因此超导金属通常在低温下使用。对于 N 个自旋的集合，自旋光子耦合可以通过称为迪克态的集体自旋激发由根 N 增强。对于足够大的 N，集体自旋光子耦合可以超过自旋退相干和腔衰减率，从而使强耦合状态变得容易实现。在这里，我们展示了室温下固态系统中的强耦合和空腔量子电动力学。通过光激发并五苯分子进入自旋三重态，自旋相移时间 T*(2) 类似于 3 mu s，我们生成了 N 类似于 10(15) 的倒置自旋系综。当耦合到由高珀塞尔因子钛酸锶介电腔支持的 1.45 GHz TE01 δ 模式（V-m 类似于 0: 25 cm(3)，Q 类似于 8,500）时，我们观察到来自集体 Dicke 态的微波发射中的拉比振荡以及由此产生的集体自旋光子极化子的 1.8 MHz 正常模式分裂。我们还观察到强耦合状态开始时的空腔保护效应，随着集体耦合的增加，极化子衰减率降低。
The strong coupling regime is essential for efficient transfer of excitations between states in different quantum systems on timescales shorter than their lifetimes. The coupling of single spins to microwave photons is very weak but can be enhanced by increasing the local density of states by reducing the magnetic mode volume of the cavity. In practice, it is difficult to achieve both small cavity mode volume and low cavity decay rate, so superconducting metals are often employed at cryogenic temperatures. For an ensembles of N spins, the spin-photon coupling can be enhanced by root N through collective spin excitations known as Dicke states. For sufficiently large N the collective spin-photon coupling can exceed both the spin decoherence and cavity decay rates, making the strong-coupling regime accessible. Here we demonstrate strong coupling and cavity quantum electrodynamics in a solid-state system at room-temperature. We generate an inverted spin-ensemble with N similar to 10(15) by photo-exciting pentacene molecules into spin-triplet states with spin dephasing time T*(2) similar to 3 mu s. When coupled to a 1.45 GHz TE01 delta mode supported by a high Purcell factor strontium titanate dielectric cavity (V-m similar to 0: 25 cm(3), Q similar to 8,500), we observe Rabi oscillations in the microwave emission from collective Dicke states and a 1.8 MHz normal-mode splitting of the resultant collective spin-photon polariton. We also observe a cavity protection effect at the onset of the strong-coupling regime which decreases the polariton decay rate as the collective coupling increases.