A research team led by Hidetoshi Katori, a researcher at RIKEN (Professor, Graduate School of Engineering, The University of Tokyo), has developed a shift in resonance frequency (optical shift) due to an optical lattice laser in an "optical lattice clock" that uses strontium (Sr) atoms. We derived the "effective magic condition" of the optical lattice that minimizes.
The current "second" is defined by the "cesium atomic clock", which is based on the microwave frequency at which the cesium atom resonates, and has a precision of 16 digits (a deviation of 6000 second in 1 million years).On the other hand, Researcher Katori devised an "optical lattice clock" that encloses atoms in a region called an optical lattice created by interfering laser light and uses the resonance frequency of the light absorbed by the atoms as a reference. An optical lattice clock with 18-digit accuracy has been realized by teams.
In conventional optical lattice clocks, a specific frequency called "magic frequency" is used under an approximation that ignores higher-order interactions between the optical lattice and atoms (such as electric quadrupoles / magnetic dipoles and superpolar interactions). An optical lattice is created with the laser light of the above, and the optical shift is set to zero.However, in order to step into the precision range of more than 18 digits, it is necessary to have "effective magic conditions" that reduce the optical shift, including higher-order effects, instead of "magic frequencies".
Therefore, this time, the research team precisely controlled the vibration quantum state of the Sr atom in the optical lattice and the intensity and frequency of the optical lattice laser, and precisely evaluated the optical shift of the optical lattice including higher-order effects.As a result, we succeeded in high-precision measurement of the higher-order polarization effect, which had not been observed experimentally so far, and based on this data, the effect of optical shift was measured with 19-digit accuracy (3000 second deviation in 1 billion years). ) Has been determined, which is an effective magic condition for reducing the intensity and frequency of the optical grid laser.
This achievement is an important step toward the realization of an optical lattice clock with 19-digit accuracy, and can be a great driving force for the redefinition of seconds.
Paper information:[Physical Review Letters] Operational Magic Intensity for Sr Optical Lattice Clocks
