東京大学物理工学科香取研究室
香取研究室の研究テーマ

1、中性原子のレーザー冷却・トラッピング

We can employ the velocity or position dependence on the exchange of momentum between atoms and photons to excert frictinal or centripetal force on atoms. These ultracold atoms cooled and trapped in the temperature of mK or uK order are good spectroscopic samples without a Doppler broadening. Because their de Broglie wavelength is much longer than that in the room temperature, its wave nature prevails through e.g. interferometry. And they are the starting point for demonstrating many other quantum mechanical effects. We are mainly playing with 88Sr (Boson) and 87Sr (Fermion) atoms.

2、光格子時計

In quest of the novel scheme for a future optical standard, we have explored the feasibility of an "optical lattice clock," in which millions of neutral atoms trapped in an engineered optical lattice serve as quantum references effectively free from light-field perturbations. In this scheme, subwavelength confinement of atoms provided by an optical-lattice with less than unity occupation eliminates both the Doppler and collisional shifts, which are known to cause major uncertainties in optical standards with freely falling atomic ensembles. By thus sharing the advantages of both, the single ion and the neutral atom based standards, the proposed scheme will allow the high accuracy and stability at the 10-18 level for an interrogation time of only 1 second. We have experimentally demonstrated the "optical lattice clock" by performing spectroscopy on the 5s2 1S0 (F=9/2) - 5s5p 3P0 (F=9/2) clock transition of 87Sr atoms trapped in a one-dimensional optical lattice.

3、アトムチップ

Coherent manipulation of atoms, which have far rich internal as well as external degree of freedom compared with electrons or photons, may open up a new field of "atomtronics" that is expected to allow advanced information processing, such as quantum computation. In this research, we propose and demonstrate Stark manipulation of atoms using electrodes microfabricated on a transparent solid surface, and realize optical access to electronic states of a singly trapped atom on the surface. We thus aim to interface "atomtronics" with existing technologies of electronics and photonics.

4、量子コンピュータ

Since the birth of quantum theory, the wave nature of the particle with mass such as electron or neutron has been recognized. Electron or neutron interferometer has been constructed for important measurements supporting the principle of quantum mechanics. Atoms, composit of elementary particles such as electrons and neutrons, were also known to have a wave nature as early as in the 1930s. However, its extreme shortness of the de Broglie wavelength due to larger mass had prevented to construct a device such as an atom interferometer. Invention and development of laser cooling and trapping technique in the late 1980s have made it possible to cool atoms whose de Broglie wavelength similar to that of light, which led to the realization of the atom interferometer. Because ultracold atoms travel in the interferometer with the velocity much slower than light, its phase sensitivity is 1010 times larger than the interferometer which uses light.