Observation of an Inner-Shell Orbital Clock Transition in Neutral Ytterbium Atoms.

We observe a weakly allowed optical transition of atomic ytterbium from the ground state to the metastable state 4f^{13}5d6s^{2} (J=2) for all five bosonic and two fermionic isotopes with resolved Zeeman and hyperfine structures. This inner-shell orbital transition has been proposed as a new frequency standard as well as a quantum sensor for new physics. We find magic wavelengths through the measurement of the scalar and tensor polarizabilities and reveal that the measured trap lifetime in a three-dimensional optical lattice is 1.

10 W injection-locked single-frequency continuous-wave titanium:sapphire laser.

High-power tunable lasers with good longitudinal and transverse modes are fundamental tools for exploring quantum physics. Here we report a high-power continuous-wave injection-locked titanium:sapphire laser with a low-loss cavity configuration, where only a laser crystal was installed in the laser cavity. Although the transverse mode was affected by a thermal lens formed in the laser crystal, the focal length of the thermal lens could be shifted via the temperature of the laser crystal holder or the pump power.

Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre.

Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy.

Manipulation of nonclassical atomic spin states.

We report successful manipulation of nonclassical atomic spin states. We apply an off-resonant noncircularly-polarized light pulse to a measurement-induced squeezed spin state of a cold atomic ensemble. By changing the pulse duration, we clearly observe a rotation of the anisotropic quantum-noise distribution in good contrast with the case of manipulation of a coherent spin state where the quantum-noise distribution is always isotropic.

Spin-singlet Bose-Einstein condensation of two-electron atoms.

We report the observation of a Bose-Einstein condensation of ytterbium atoms by evaporative cooling in a novel crossed optical trap. Unlike the previously observed condensates, a ytterbium condensate is a two-electron system in a singlet state and has distinct features such as the extremely narrow intercombination transitions which are ideal for future optical frequency standard and the insensitivity to external magnetic field which is important for precision coherent atom optics, and the existence of the novel metastable triplet states generated by optical excitation from the singlet state.