Seiji Sugawa

Submicron spatial modulation of an interatomic interaction in a Bose-Einstein condensate.

We demonstrate submicron spatial control of interatomic 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 every 278 nm is monitored by a diffraction pattern in a time-of-flight image. We observe a wide scattering length control of up to 250 nm. The demonstrated spatial modulation of the scattering length proves that high resolution control of atomic interactions is possible.

Realization of a SU(2) X SU(6) System of Fermions in a Cold Atomic Gas

We report the realization of a novel degenerate Fermi mixture with an SU(2)×SU(6) symmetry in a cold atomic gas. We successfully cool the mixture of the two fermionic isotopes of ytterbium Yb with the nuclear spin I = 1/2 and Yb with I = 5/2 below the Fermi temperature TF as 0.46TF for Yb and 0.54TF for Yb. The same scattering lengths for different spin components make this mixture featured with the novel SU(2)×SU(6) symmetry. The nuclear spin components are separately imaged by exploiting an optical Stern-Gerlach effect. In addition, the mixture is loaded into a 3D optical lattice to implement the SU(2)×SU(6) Hubbard model. This mixture will open the door to the study of novel quantum phases such as a spinor Bardeen-Cooper-Schrieffer-like fermionic superfluid.

An SU(6) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

A multicomponent gas of ytterbium atoms accommodates more entropy in its spin degrees of freedom than does its two-component analogue, leading to a lower effective temperature, and an easy route for cooling ultracold fermions towards a Mott-insulating state.

Direct observation of zitterbewegung in a Bose–Einstein condensate

Zitterbewegung, a force-free trembling motion first predicted for relativistic fermions like electrons, was an unexpected consequence of the Dirac equations unification of quantum mechanics and special relativity. Though the oscillatory motions large frequency and small amplitude have precluded its measurement with electrons, zitterbewegung is observable via quantum simulation. We engineered an environment for 87Rb Bose–Einstein condensates where the constituent atoms behaved like relativistic particles subject to the one-dimensional Dirac equation. With direct imaging, we observed the sub-micrometre trembling motion of these clouds, demonstrating the utility of neutral ultracold quantum gases for simulating Dirac particles.

Bose-Einstein condensation of an ytterbium isotope

We report the observation of a Bose-Einstein condensate in a bosonic isotope of ytterbium

All-Optical Formation of Quantum Degenerate Mixtures

(^{170}\mathrm{Yb})

Mott insulator of ultracold alkaline-earth-metal-like atoms

. More than

Control of Resonant Interaction between Electronic Ground and Excited States

{10}^{6}

Observation of ap-wave optical Feshbach resonance

atoms are trapped in a crossed optical dipole trap and cooled by evaporation. Condensates of approximately

Second Chern number of a quantum-simulated non-Abelian Yang monopole

{10}^{4}