The Nuclear Clocks are in Research

Published:2012/3/21 2:23:00 Author:Li xiao na From:SeekIC

For scientist in the search of the ultimate frequency reference, to probe the core of a thorium atom with a petahertz laser is meaningful. If it can be achieved, this so-called nuclear clock could complement atomic clocks. Although the atomic clocks is precise enough in many applications, the unclear clock is more suitable for some other applications, for example, the unclear clock is a good way to study the laws of physics which may not be constant in time.

The accuracy of atomic clocks is derived from induced oscillations of electrons in atoms. The magnetic and electrical fields will bring influence to the atomic clocks; therefore, this clock will drift four seconds in the life time of this universe. Neutrons are much heavier than electrons, and packed into the dense atomic nucleus. The oscillation rate of unclear clock will not be influenced by any external perturbations, for the neutron is held so tightly to the nucleus.

The nucleus of a thorium 229 ion will be boosted to a higher energy state with a laser operating at around 1015Hz. Scientists in the Georgia Tech use lasers to orient the electrons in a very specific way, and they also use the neutron of an atomic nucleus as the clock pendulum. Creating a high energy stage for the laser enables the scientists to set frequency very precisely. The ion will need to be maintained at tens of µK to keep it still, something usually done by laser cooling.

A problem will be aroused by laser cooling because light is also used to create the time keeping oscillations. In order to solve this problem, a single thorium 232 ion will be included with the thorium 229 ion that will be used for time-keeping. The heavier ion is responding to a different wavelength than the thorium 229 ion, allowing it to be cooled and act as a heatsink.

All in all, it will still be a while before the scientists can produce a nuclear clock, though they believe that it has possibility to make one.

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