Terraciano Matthew L, Bashkansky Mark, Fatemi Fredrik K
Optical Sciences Division, Naval Research Laboratory, Washington, DC 20375, USA.
Opt Express. 2008 Aug 18;16(17):13062-9. doi: 10.1364/oe.16.013062.
We demonstrate a technique for imaging magnetic fields using velocity-selective two-photon resonances in a cold atom cloud. Freely expanding (85)Rb atoms released from a magneto-optical trap are exposed to a brief (approximately 1 ms), off-resonant, retro-reflected laser pulse in a lin-perp-lin configuration. Two-photon resonance between magnetic sublevels occurs only for atoms in narrow velocity classes dependent on the magnetic field strength. The momentum of resonant atoms is altered by the pulse, and this two-photon momentum change is easily visible after further ballistic expansion. When the momentum pulse is applied to an atom cloud with finite size, magnetic field variations across the sample result in position-dependent features in images of the expanded cloud. We demonstrate the technique by imaging magnetic field variations over approximately 5 mm with approximately 250 microm spatial resolution.
我们展示了一种利用冷原子云中的速度选择性双光子共振对磁场进行成像的技术。从磁光阱中释放的自由膨胀的（85）Rb原子，在“线偏振-垂直-线偏振”配置下，暴露于一个短暂的（约1毫秒）、非共振的、后向反射激光脉冲。磁子能级之间的双光子共振仅发生在取决于磁场强度的窄速度类别的原子中。共振原子的动量被脉冲改变，并且在进一步的弹道膨胀后，这种双光子动量变化很容易观察到。当动量脉冲施加到具有有限尺寸的原子云上时，样品上的磁场变化会导致膨胀云图像中出现位置相关的特征。我们通过以约250微米的空间分辨率对约5毫米范围内的磁场变化进行成像来演示该技术。
