Hate to be that guy when it comes to being pedantic about headlines, but wouldn't a `quantum leap` in accuracy be rather un-noteworthy?
You'll never walk alone down the road of headline-aimed pedantry, friend
Atomic Clocks Make a Quantum Leap in Accuracy
21–30 of 45 posts
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#22This could be the basis of a future tricorder or Star Trek-like sensor array. Three ultra-sensitive clocks in an array should be able to infer mass and motion both for the unit and objects in the local area indirectly. Relativistic effects are minuscule, but not non-existent. Extremely-tuned clocks would have some pretty cool capabilities.
One thing I've spent some time thinking about is whether it would be possible to use atomic clocks to get a better measurement of the gravitational constant G. (G is by far the most poorly known of all the fundamental physical constants.) The idea would be to build a sphere whose mass is very precisely known and place one clock near the mass and one clock far away. By measuring the gravitational time dilation you cou…
How about a wolframalpha link to those calculations? Assuming they're simple enough.
Also, would this require the clocks and mass to be far away from other large masses like the earth?
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#23One thing I'm really curious about: How can you measure the accuracy of the world's most accurate clock?
By definition there would be no more accurate timing device to benchmark it against so is the accuracy cited in the article only theoretical?
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#24Hate to be that guy when it comes to being pedantic about headlines, but wouldn't a `quantum leap` in accuracy be rather un-noteworthy?
I can here to make that exact comment. It always irks me that a lot of people don't realize 'quantum' == 'small'.
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#25Can I have a chip-scale one? With zero jitter? On every motherboard? Feeding TSC clock? Please? Pretty pretty pleaase?
There are already very accurate clocks on your motherboard. Your problem has more to do with modern multi-processor design.
That depends on what you mean by accurate, and even then they pretty much suck. Clocks are "inaccurate" in a few ways. One of these ways is very short-term: variations in exactly when the clock edges arrive at frequencies near the clock frequency. Others of these are long-term: how far the clock is from it's target rate over decades. Between these there's a whole spectrum of different noise frequencies.
The oscillators on your motherboard, with very basic temperature correction, very basic calibration and only very basic quality control don't tend to do very well on any of these measures. They tend to do better on the high-frequency measures of clock badness, and worse on low-frequency measures, but they aren't stellar in any area. The end-to-end time system, including NTP and software-level drift correction, does an OK job in some circumstances. It does a horrible job in others.
If you go through life assuming your computer's local clock isn't literally out to get you, you're going to be disappointed.
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#26The coolest part it that it improves both stability and accuracy. Cesium is often touted as a good clock but it only has good accuracy. The short-term stability has more noise than something like a Rubidium clock that is very stable on the short-term but inaccurate(relative to cesium anyway) on the long term. This is cool because it is the best in both dimensions.
The phase noise (really short term stability) of a rubidium oscillator is rather poor compared to on ovenized quartz oscillator. So what I really want is a strontium disciplined OCXO.
Years ago I was involved in some work on clocks that needed very high performance at low cost. We ended up with OCXOs GPS-disciplined over some of their frequency and atomic clock disciplined (cesium, IIRC) over another part of the range.
Telling the time is hard.
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#27Hate to be that guy when it comes to being pedantic about headlines, but wouldn't a `quantum leap` in accuracy be rather un-noteworthy?
I can here to make that exact comment. It always irks me that a lot of people don't realize 'quantum' == 'small'.
It depends heavily on the exact usage: http://dictionary.reference.com/browse/quantum?s=t
The salient feature here is that quanta are discrete and a transition from one to another is a jump rather than a smooth or continuous shift.
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#28Hate to be that guy when it comes to being pedantic about headlines, but wouldn't a `quantum leap` in accuracy be rather un-noteworthy?
Not to be that guy, but Merriam-Webster is pretty clear on the definition: `a sudden large change, development, or improvement`[1]
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#29At this level of accuracy things are pretty strange. It used to bug me when you had to tune RF circuits at a distance with non-conductive tools because your body capacitance would throw the tuning off. Having a clock that just being near it will change what time it reads, well that is a whole different ballgame of weird is it not?
On a science note, why isn't this a gravity wave detector anyway?
Re: Atomic Clocks Make a Quantum Leap in Accuracy
#30Earlier quoted context omitted.
The phase noise (really short term stability) of a rubidium oscillator is rather poor compared to on ovenized quartz oscillator. So what I really want is a strontium disciplined OCXO.
Years ago I was involved in some work on clocks that needed very high performance at low cost. We ended up with OCXOs GPS-disciplined over some of their frequency and atomic clock disciplined (cesium, IIRC) over another part of the range. Telling the time is hard.
Cool. I bought a couple of HP Z3801A recently for home lab use. Also have an Arbiter GPS disciplined clock at work as a frequency standard for my RF equipment; they use one of the Wenzel OCXOs that has the lowest phase noise you can buy.