Nakamura Ippei, Yoshihiro Tatsuya, Inagawa Hironori, Fujiyoshi Satoru, Matsushita Michio
Department of Physics, Tokyo Institute of Technology, Ookayama 2-12-1 Meguro Tokyo, 152-8550 Japan.
Sci Rep. 2014 Dec 8;4:7364. doi: 10.1038/srep07364.
Optical read-out and manipulation of the nuclear spin state of single rare-earth ions doped in a crystal enable the large-scale storage and the transport of quantum information. Here, we report the photo-luminescence excitation spectroscopy results of single Pr(3+) ions in a bulk crystal of LaF3 at 1.5 K. In a bulk sample, the signal from a single ion at the focus is often hidden under the background signal originating from numerous out-of-focus ions in the entire sample. To combine with a homemade cryogenic confocal microscope, we developed a reflecting objective that works in superfluid helium with a numerical aperture of 0.99, which increases the signal by increasing the solid angle of collection to 1.16π and reduces the background by decreasing the focal volume. The photo-luminescence excitation spectrum of single Pr(3+) was measured at a wing of the spectral line of the (3)H4 → (3)P0 transition at 627.33 THz (477.89 nm). The spectrum of individual Pr(3+) ions appears on top of the background of 60 cps as isolated peaks with intensities of 20-30 cps and full-width at half-maximum widths of approximately 3 MHz at an excitation intensity of 80 W cm(-2).
对掺杂在晶体中的单个稀土离子核自旋态进行光学读出和操控，可实现量子信息的大规模存储和传输。在此，我们报告了在1.5 K温度下，块状LaF3晶体中单个Pr(3+)离子的光致发光激发光谱结果。在块状样品中，焦点处单个离子的信号常常隐藏在整个样品中众多离焦离子产生的背景信号之下。为了与自制的低温共聚焦显微镜相结合，我们开发了一种反射物镜，它在超流氦中工作，数值孔径为0.99，通过将收集立体角增加到1.16π来增强信号，并通过减小焦体积来降低背景。单个Pr(3+)的光致发光激发光谱是在627.33 THz（477.89 nm）处(3)H4 → (3)P0跃迁谱线的一侧测量的。在80 W cm(-2)的激发强度下，单个Pr(3+)离子的光谱以孤立峰的形式出现在60 cps的背景之上，峰强度为20 - 30 cps，半高宽约为3 MHz。
