Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
Department of Physics, Duke University, Durham, North Carolina 27708, USA.
Phys Rev Lett. 2018 Oct 19;121(16):163404. doi: 10.1103/PhysRevLett.121.163404.
Optical control enables new high resolution probes of narrow collisional (Feshbach) resonances, which are strongly dependent on the relative momentum of colliding atom pairs, and important for simulating neutron matter with ultracold atomic gases. We demonstrate a two-field optical vernier, which expands kHz (mG) magnetic field detunings near a narrow resonance into MHz optical field detunings, enabling precise control and characterization of the momentum-dependent scattering amplitude. Two-photon loss spectra are measured for the narrow resonance in ^{6}Li, revealing rich structure in very good agreement with our theoretical model. However, anomalous overall frequency shifts between the measured and predicted two-photon spectra are not yet explained.
光学控制使得对狭窄碰撞（Feshbach）共振的新高分辨率探测成为可能，这些共振强烈依赖于碰撞原子对的相对动量，对于使用超冷原子气体模拟中子物质非常重要。我们展示了一种双场光学游标，它将 kHz（mG）磁场失谐扩展到 MHz 光场失谐附近，从而能够精确控制和表征与动量相关的散射幅度。我们测量了 ^{6}Li 中狭窄共振的双光子损耗谱，发现与我们的理论模型非常吻合的丰富结构。然而，测量和预测的双光子谱之间的异常整体频率位移尚未得到解释。
