A New Generation of Atomic Clocks

[marcus]

This was just posted today, and looks interesting
http://arxiv.org/pdf/1309.1137.pdf
A New Generation of Atomic Clocks: Accuracy and Stability at the 10^-18 Level
B. J. Bloom et al
The exquisite control exhibited over quantum states of individual particles has revolutionized the field of precision measurement, as exemplified by the most accurate atomic clock realized in single trapped ions. Whereas many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks, their accuracy has remained 20 times worse. Here we demonstrate, for the first time, that a many-atom system achieves accuracy (6x10^-18) better than a single ion-based clock, with vastly reduced averaging times (3000 s). This is the first time a single clock has achieved the best performance in all three key ingredients necessary for consideration as a primary standard - stability, reproducibility, and accuracy. This work paves the way for future experiments to integrate many-body quantum state engineering into the frontiers of quantum metrology, creating exciting opportunities to advance precision beyond the standard quantum limit. Improved frequency standards will have impact to a wide range of fields from the realization of the SI units, the development of quantum sensors, to precision tests of the fundamental laws of nature.
--- National Institute of Standards and Technology and University of Colorado, Boulder, CO

 

[Vanadium 50]

As you can see, we're starting to come up against the wall with atomic clocks. The next step will be nuclear clocks, built around the Th-229m isomer. This is predicted to have a Q-value about a thousand times better than the best atomic clocks, and much better environmental isolation since its a nuclear (not atomic) transition. The "gamma" from this transition is very, very soft - it's actually in the ultraviolet.

 

[Drakkith]

The "gamma" from this transition is very, very soft - it's actually in the ultraviolet.

Well that's nice!

 

[f95toli]

As you can see, we're starting to come up against the wall with atomic clocks. The next step will be nuclear clocks, built around the Th-229m isomer. This is predicted to have a Q-value about a thousand times better than the best atomic clocks, and much better environmental isolation since its a nuclear (not atomic) transition. The "gamma" from this transition is very, very soft - it's actually in the ultraviolet.

One problem that also needs to be solved is time transfer. There are now several experiments that have demonstrated clocks with accuracies in the 5e-18 range. However, the clocks are not very useful unless you can transfer the time; current satellite based systems are nowhere near good enough and even using dedicated fibre you would struggle to maintain this accuracy; especially if you want to replace the Cs fountains used for the UTC.