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Atomic nucleus excited with laser: A breakthrough after decades

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Re: Atomic nucleus excited with laser: A breakthrough after decades

#61

Post by rpastuszak »

lifeisstillgood wrote: post #51

>>> For example, the Earth's gravitational field could be analyzed so precisely that it could provide indications of mineral resources Hold on how does that work? I have had a sort of sci-fi idea that sufficiently sensitive gravitational field measurements coukd detect the passing of submarines (I am not sure on the maths tbh) - which would render a lot of nuclear strategy moot. Just need to get a grasp on the maths

Check out quantum navigation systems. They're not used to track submarines, but rather as an alternative to GPS for submarines (using tiny differences in the Earth's gravitational field to determine position).

(IIRC) Royal Navy trialed it (officially) for the first time last year.

Re: Atomic nucleus excited with laser: A breakthrough after decades

#62

Post by nullc »

pzs wrote: post #32
irjustin wrote: post #28

Earlier quoted context omitted.

The article directly stated more precise atomic clocks.

Not a physicist, so I am asking out of curiosity and to learn: have the limitations to the precision of current atomic clocks posed any problems?

We derrive most of our other units from time, so differences in time accuracy translate into metrology improvements more generally.

Existing atomic clocks based on electrical interactions are extremely sensitive to the surrounding magnetic and electrical environment-- so for example accuracy is limited by collisions with other atoms, so state of the art atomic clocks have optically trapped clouds in high vacuums. Beyond limiting their accuracy generally makes the instruments very complex.

One could imagine an optical-nuclear atomic clock in entirely solid state form on a single chip with minimal support equipment achieving superior stability to a room sized instrument.

Re: Atomic nucleus excited with laser: A breakthrough after decades

#63

Post by perihelions »

meindnoch wrote: post #53
lifeisstillgood wrote: post #51

>>> For example, the Earth's gravitational field could be analyzed so precisely that it could provide indications of mineral resources Hold on how does that work? I have had a sort of sci-fi idea that sufficiently sensitive gravitational field measurements coukd detect the passing of submarines (I am not sure on the maths tbh) - which would render a lot of nuclear strategy moot. Just need to get a grasp on the maths

https://apps.dtic.mil/sti/pdfs/AD1012150.pdf Gravitational Detection of Submarines, PM Moser 1989

Look at what paper actually says: flat "not achievable" in the abstract; and the scaling laws on page 4 are third- and fourth- inverse powers of distance (!!!!); and on page 7 they're considering ranges of the same length scale as a submarine itself (few hundreds of meters), and even there it's hopeless.

This one's never going to happen.

Geologic mass concentrations are an entirely different story: you get a gravitational monopole, which is a more reasonable inverse square law. (No monopoles for a submarine, because by design they have a mean density equal to water—as the paper explains).

Re: Atomic nucleus excited with laser: A breakthrough after decades

#64

Post by graycat »

greenbit wrote: post #52
huytersd wrote: post #38

Earlier quoted context omitted.

But then what happens? Does it expel an electron/release energy etc.?

Probably just emits another photon of the exact same wavelength a short time later. The time would be probabilistic, like 50% chance of emission in X amount of time.

Physics does not emphasize this, but the half life concept essentially assumes a Poisson process (Cinlar, Stochastic Processes) which has a Markov (past and future conditionally independent given the present, details from the Radon-Nikodym theorem, with a cute von Neumann polynomial proof, Rudin, Real and Complex Analysis) assumption.

The half life concept seems to be standard over much of physics.

That a Markov assumption could hold might suggest some new physics.

Re: Atomic nucleus excited with laser: A breakthrough after decades

#67

Post by fodkodrasz »

lifeisstillgood wrote: post #51

>>> For example, the Earth's gravitational field could be analyzed so precisely that it could provide indications of mineral resources Hold on how does that work? I have had a sort of sci-fi idea that sufficiently sensitive gravitational field measurements coukd detect the passing of submarines (I am not sure on the maths tbh) - which would render a lot of nuclear strategy moot. Just need to get a grasp on the maths

Actually the method of detecting mineral deposits by mapping gravitational field is already in use since a long time!

The Eotvos pendulum (an instrument aka. Eotvos torsion balance) designed in 1888 started this kind of measurement. It was used commonly by the 1920s by geophysicist for mapping underground deposits by measuring the gradient of the gravitational field very precisely.

This instrument was deprecated later by even better tools for surveying.

The instrument was initially constructed for the experiment showing that inertial and gravitational mass are the same (well, linearly correlated) to a great precision: https://en.wikipedia.org/wiki/E%C3%B6tv%C3%B6s_experiment

https://www.nature.com/articles/118406a0 (pretty useless link, but a famed periodical)

Detecting submarines is way harder, practically impossible. as others have already pointed out.

Re: Atomic nucleus excited with laser: A breakthrough after decades

#69

Post by limbicsystem »

yread wrote: post #25

Is there some direct application? Like using the excitation states of different atoms for storing information?

I >think< that this will enable more accurate magnetometers (see OPM-MEG and atomic clock magnetometers). Which can be used, among other things, for measuring neuronal activity.
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