The advancement in the field of quantum degenerate gas has enabled to engineer wide spectrum of physical environment. Particularly, the study of many-body physics using the cold atom has been equipped with well controllable temperature, dimensionality, interaction strength, and spin mixtures. The rich controllability resulted in exciting simulations, including superfluid to Mott-insulator transition and itinerant ferromagnetism of delocalized fermions. Feshbach resonances with a magnetic tuning of the hyperfine energy bound levels with respect to the energy level of the incoming scattering state can vary the scattering length, and therefore the interatomic-interaction.
Ytterbium atoms, investigated at Kyoto University, however, do not possess Hyper-fine structure due to the ground state. Instead of the magnetic approach for the Feshbach resonances, we have been investigating a use of Optical Feshbach Resonances (OFR) for the control of the interatomic interaction. We discuss a demonstration of nanometer-scale spatial control of inter-atomic interactions in a Bose-Einstein condensate of ytterbium(Yb). A pulsed optical standing wave, tuned near an optical Feshbach resonance varies the s-wave scattering length continuously across the standing wave pattern. The modulated mean-field energy with a spatial period of every 278 nm is monitored by a diffraction pattern in a time-of-flight image. We observe a wide scattering length control of more than few hundred nanometers. The demonstrated spatial modulation of the scattering length proves that the high resolution control of atomic interactions is possible. Additionally, the optical nature of the control enables fast manipulation of the interatomic-interaction. This demonstration provide wide variety of possibilities in manipulation of cold atoms in a context of quantum simulation, computation, and manybody physics.