All-optical realization of quantum degeneracy of Yb atoms

Yb原子量子简并性的全光实现

• 批准号: 13640403
• 负责人: TAKAHASHI Yoshiro
• 金额: $ 2.24万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640403/
• 关键词: LASER COOLING; BOSE CONDENSATION; OPTICAL TRAP; Yb ATOM; Yb MOLECULE; INJECTION LOCK; EVAPORATIVE COOLING; LASER DIODE; ボース・アインシュタイン凝縮; フェルミ縮退; BCS; 量子統計

BECs of two-electron atoms such as ytterbium (Yb) and alkali-earth atoms have distinct features such as the extremely narrow intercombination transitions which are ideal for future optical frequency standard and the insensitivity to external magnetic field which is important for precision coherent atom optics. Here we report the achievement of BEC of Yb atoms by all-optical means in a novel crossed far-off resonant trap (FORT). The evaporative cooling is carried out by gradually decreasing the horizontal FORT beam power in 2 sec., while keeping the vertical FORT beam power constant. When the final trap depth is 2.2 ,, K, anisotropic expansion after release from the trap has appeared. The number of atoms in the condensate is typically 5×10^3. The critical temperature is about 0.7 ,, K and the peak atom density is 7×10^<14> cm^<-3>. The lifetime of the condensate is about 500 ms, and we infer an upper bound for the three-body loss coefficient of 4×10^<-30> cm^6 s^<-1>.From the behavior of the condensate, we have estimated the scattering length of ^<174>Yb. The chemical potential of 0.55, K is obtained from the fit with the horizontally expanded widths at ten TOF times, which gives the scattering length of 6 nm with the uncertainty of -5 and +10 nm. By combining this result with our recent photoassociation experiment, we conclude that the scattering length is between 1 to 3 nm.The existence of rich varieties of stable isotopes of five bosons (^<168>Yb, ^<170>Yb, ^<172>Yb, ^<174>Yb, and ^<176>Yb) and two fermions (^<171>Yb and ^<173>Yb) will allow us to study various interesting quantum degenerate gases using Yb atoms. In addition, the successful demonstration of Yb BEC in the present work would also promise the formation of BEC of alkali-earth atoms.

镱 (Yb) 和碱土原子等双电子原子的 BEC 具有独特的特征，例如极窄的组合跃迁，这对于未来的光学频率标准是理想的，并且对外部磁场不敏感，这对于精密相干原子光学非常重要。在这里，我们报告了在新型交叉远距共振陷阱（FORT）中通过全光学手段实现 Yb 原子 BEC 的成就。通过在 2 秒内逐渐降低水平 FORT 光束功率，同时保持垂直 FORT 光束功率恒定来进行蒸发冷却。当最终陷阱深度为2.2,,K时，陷阱释放后出现各向异性膨胀。凝聚体中的原子数通常为 5×10^3。临界温度约为0.7℃，K，峰值原子密度为7×10^<14>cm^-3>。凝聚体的寿命约为500 ms，我们推断三体损耗系数的上限为4×10^<-30> cm^6 s^<-1>。根据凝聚体的行为，我们估计了^<174>Yb的散射长度。 0.55 K 的化学势是通过十个 TOF 倍的水平扩展宽度拟合得到的，这给出了 6 nm 的散射长度，不确定性为 -5 和 +10 nm。将此结果与我们最近的光缔合实验相结合，我们得出散射长度在1至3 nm之间的结论。五种玻色子（^<168>Yb、^<170>Yb、^<172>Yb、^<174>Yb和^<176>Yb）和两种费米子（^<171>Yb和^<171>Yb）的稳定同位素种类丰富。 ^<173>Yb) 将使我们能够 使用 Yb 原子研究各种有趣的量子简并气体。此外，目前工作中Yb BEC的成功演示也预示着碱土原子BEC的形成。

项目成果

K.Honda et al.: "Optical dipole force trapping of a fermion-boson mixture of ytterbium"Phys.Rev. A. 66・2. 021401-1-021401-4(R) (2002)

K.Honda等：“镱的费米子-玻色子混合物的光学偶极力捕获”Phys.Rev. 66・2（2002）

K. Honda et al.: "Optical dipole force trapping of a fermion-boson mixture of ytterbium"Phys. Rev. A. 66・2. 021401-1-4(R) (2002)

K. Honda 等：“镱的费米子-玻色子混合物的光学偶极力捕获”Phys Rev. A. 021401-1-4(R) (2002)

高橋義朗 ほか: "イッテルビウム原子のレーザー冷却とその応用"日本物理学会誌. 57・6. 413-416 (2002)

高桥义郎等：“镱原子的激光冷却及其应用”日本物理学会杂志57・6（2002）。

K.Toyoda: "Magnetic Resonance Imaging of Bose-Einstein condensates"App. Phys. B. 74・2. 115-120 (2002)

K.Toyoda：“玻色-爱因斯坦凝聚体的磁共振成像”App.B.74·2。

高橋義朗ほか: "イッテルビウム原子のレーザー冷却とその応用"日本物理学会誌. 57・6. 413-416 (2002)

高桥义郎等：“镱原子的激光冷却及其应用”日本物理学会杂志57・6（2002）。