High-Cooperativity Coupling of a Rare-Earth Spin Ensemble to a Superconducting Resonator Using Yttrium Orthosilicate as a Substrate
High-Cooperativity Coupling of a Rare-Earth Spin Ensemble to a Superconducting Resonator Using Yttrium Orthosilicate as a Substrate
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DOI：
10.1103/physrevapplied.11.054082
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发表时间：
2019-05
影响因子：
4.6
通讯作者：
Gavin Dold;C. Zollitsch;James O'Sullivan;S. Welinski;A. Ferrier;P. Goldner;S. D. Graaf;T. Lindström;J. Morton
中科院分区：
文献类型：
--
作者：
Gavin Dold;C. Zollitsch;James O'Sullivan;S. Welinski;A. Ferrier;P. Goldner;S. D. Graaf;T. Lindström;J. Morton
正硅酸钇（YS_2SiO_5 $，或YSO）已被证明是用于微波量子存储器和具有微波接口的光存储器的示范中的稀土离子的方便的基质，并且由于其有利的光学和自旋性质而显示出用于相干微波-光转换的前景。这种微波应用所需的强耦合可以使用直接在Y$_2$SiO$_5$上图案化的超导谐振器来实现，因此我们在这里研究使用Y$_2$SiO$_5$作为用于超导混合器件制造的蓝宝石或硅衬底的替代物。在掺Nd ~（145）的Y_2SiO_5衬底上制作了频率为6.008GHz、功率品质因数为400000的NbN谐振器。介电损耗的测量结果为损耗角正切$\tan\delta = 4 \times 10^{-6}$，与蓝宝石相当。电子自旋共振（ESR）的测量使用的谐振器显示的特性的角度依赖性预期从各向异性的Nd$^{145}$自旋，和谐振器和电子自旋之间的耦合强度是在高协同制度（$C = 30$）。这些结果表明，Y2 SiO 5是低损耗、高Q微波谐振器的优良衬底，特别是在用于耦合到光学可接近的稀土自旋的应用中。
Yttrium orthosilicate (Y$_2$SiO$_5$, or YSO) has proved to be a convenient host for rare-earth ions used in demonstrations of microwave quantum memories and optical memories with microwave interfaces, and shows promise for coherent microwave--optical conversion owing to its favourable optical and spin properties. The strong coupling required by such microwave applications could be achieved using superconducting resonators patterned directly on Y$_2$SiO$_5$, and hence we investigate here the use of Y$_2$SiO$_5$ as an alternative to sapphire or silicon substrates for superconducting hybrid device fabrication. A NbN resonator with frequency 6.008 GHz and low power quality factor $Q \approx 400000$ was fabricated on a Y$_2$SiO$_5$ substrate doped with isotopically enriched Nd$^{145}$. Measurements of dielectric loss yield a loss-tangent $\tan\delta = 4 \times 10^{-6}$, comparable to sapphire. Electron spin resonance (ESR) measurements performed using the resonator show the characteristic angular dependence expected from the anisotropic Nd$^{145}$ spin, and the coupling strength between resonator and electron spins is in the high cooperativity regime ($C = 30$). These results demonstrate Y$_2$SiO$_5$ as an excellent substrate for low-loss, high-Q microwave resonators, especially in applications for coupling to optically-accessible rare earth spins.