Nist: New Optical Clock More Accurate Than Cesium

LordPhatal writes "NIST researchers have demonstrated a new kind of atomic clock that has the potential to be up to 1,000 times more accurate than today's best clock. The new clock is based on an energy transition in a single trapped mercury ion.

Comments

And in a year, they'll be using alcohol instead.

[tunah]

Duh! When this clock breaks the mercury will go everywhere! They already went through this phase with thermometers.

Now we need a whole new...

[itwerx]

...nursery rhyme to replace Hickory Dickory Dock:

Flappity floppity flip,
A mouse on a moebius strip,
The strip revolved,
The mouse dissolved,
In a chronodimensional skip!

:)

Go down and take a tour!

[hound3000]

The NIST labs out in Boulder, CO is a fabulous place to go and visit if you ever find yourself in town, or in Denver. They will gladly take you on a tour, and show you all sorts of interesting toys that they have. Probably the best part of the tour for me was the liquid hydrogen. Even better was touching it. Yes I did, yes I still have all my digits. Basically, it is exactly the same concept as fire; move your hand thru it very quickly. In this case, touch it quickly and retract. The tour guide also shrank a balloon completely down, as we all watched, as it slowly got bigger when he took it back out. And of course on the tour, was getting to see the atomic clock. (On the other side of a window of course.) Check it out!

And if you are in Boulder, and enjoy tea, make sure to take a tour of the Celestial Seasonings Tea Plant. If you have sinus problems, their Peppermint room will take care it, pronto.

Re:Go down and take a tour!

[Gopher]

Unfortunately, tours are suspended due to security concerns. :( It's too bad, really, becuase I agree that the tour is really cool.

However, you can take an online tour if that floats your boat.

Hmm....

[rtaylor]

I've always wondered just how they determine how reliable a clock is.

Afterall, can't measure meters without a meterstick. Do they simply take a N Cesium clocks and average out their time to determine how close a single Mercury based clock sticks to it? Or did I miss the memo where we could acurrately time trillionths of a second?

Re:Hmm....

[norton_I]

Basically, the accuracy of a reference clock in principle determined by making two identical clocks, starting them synchronized, and measuring how long before they drift by an average of 1 second.

This has to do with how cold your atomic fountain is, and how well you isolate the particular magnetic sublevel you define the second in terms of.

Now, if you want to move to a mercury standard clock, you can do two things: first, calculate with QED the ratio of the freqencies between the transitions in cesium and mecury of interest. I don't know if we can do this well enough for these purposes or not. Second, you can redefine the second in terms of the oscillation frequency of some mercury transition at least within the accuracy of a current cesium clock.

The important thing to note is that mand physicists don't really care about how long a second is, as much as they care that two clocks run at the same rate, even if it is wrong.

Re:And in a year, they'll be using alcohol instead

[Anonymous Coward]

well, ONE single ion can only go SOMEwhere, not EVERYwhere, unless they know its momentum very precisely.

Re:um

[akiaki007]

We know how long a second is. Time as we measure it is based on Earth's rotation and revolution.

What this measument is, is that it will not deteriorate over time as most methods of time measurement do currently. That is why it is so accurate. What that really means it that over time it will prove to be more accurate than anything else that we have created. A second will still be a second, and it's lenght will not change now.

Re:um

[esonik]

The above wording is imprecise. 9,192,631,770 Hz is the frequency of the electromagnetic wave that triggers a certain transition in a cesium-133 atom. So, what oscillates is not the complete atom, but the electric and magnetic field. Details can be found here

How do they count the ticks?

[mmontour]

One advantage of the new clock is that it ticks much faster. Today?s international time and frequency standards, such as NIST-F1, measure an atomic resonance of about 9 billion cycles per second. By contrast, the new NIST device monitors an optical frequency more than 100,000 times higher or about 1 quadrillion (US) cycles per second.

A 9 GHz oscillation can be hooked up directly to electronic circuits, counters, PLLs, etc. My first question when I read this article was, how the heck do you synchronize anything else to a "frequency" that's in the optical / ultraviolet range? I found some more information on this page and this one, so I guess that's how this new clock works.

Re:um

[CentrX]

Originally, the second was defined to be 1/86,400 of the mean solar day. Because this is inaccurate due to irregularities in the Earth's rotation, that is the length of the second would change, finer standards were chosen. These finer standards are based on the original standard, but because they are defined in another way, they will not change unless the fundamental properties of the universe do.