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Image of a Single, Trapped Atom

Skwim

Veteran Member


"A mind-bending image of a single strontium atom, held near motionless by electric fields, has won the overall prize
in a national science photography competition, organized by the Engineering and Physical Sciences Research Council (EPSRC).


“In the center of the picture, a small bright dot is visible – a single positively-charged strontium atom. It is held nearly motionless by electric fields emanating from the metal electrodes surrounding it. […] When illuminated by a laser of the right blue-violet color, the atom absorbs and re-emits light particles sufficiently quickly for an ordinary camera to capture it in a long exposure photograph. [..] Laser-cooled atomic ions provide a pristine platform for exploring and harnessing the unique properties of quantum physics. They are used to construct extremely accurate clocks or, as in this research, as building blocks for future quantum computers, which could tackle problems that stymie even today’s largest supercomputers.”
source
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Skwim

Veteran Member
That's a big atom if I can see it.

Is the picture magnified?
It may be magnified, but even so, it's quite immense. Just consider the atoms that go into making up the device it's contained in; it's nowhere near small enough to qualify as one of those. The only thing I can think of is that it's some kind of a "flare up" of the re-emitted light coming off the atom. :shrug:

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sandy whitelinger

Veteran Member
It may be magnified, but even so, it's quite immense. Just consider the atoms that go into making up the device it's contained in; it's nowhere near small enough to qualify as one of those. The only thing I can think of is that it's some kind of a "flare up" of the re-emitted light coming off the atom. :shrug:

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That is what seems like to me. Pretty cool though.
 

suncowiam

Well-Known Member
It may be magnified, but even so, it's quite immense. Just consider the atoms that go into making up the device it's contained in; it's nowhere near small enough to qualify as one of those. The only thing I can think of is that it's some kind of a "flare up" of the re-emitted light coming off the atom. :shrug:

.

Uncertainty principle, I would guess. Low uncertainty in speed leads to large uncertainty in position.

I thought being able to perceive something requires an electron of photon being able to bounce off the material and also something concerning the wavelength of the particle at travel...

Let me try to dig up the physics behind this. To me, it seems not possible to be able to see an atom since we need an electron microscope to view molecules.

[Edited]
Here's something from the web:
Is it possible to "see" atoms?

"Now, can we "see" atoms? This depends, as I already hinted at, what you mean by "see". If you mean "make a picture in visible light", then you can't do that. In microscopy, there is a rule of thumb that the smallest things you can distinguish with a perfectly engineered microscope have to have a size about half the wavelength of the light you're shining at it. The more exact version of this is known as the Abbé difraction limit. Visible light has wavelength of about 400-700 nanometres. This is of course about 4000-7000 times as much as the diameter of the atom, so there is indeed no way we can see an atom with a (diffraction) microscope using light. [As suggested in the comments, there are a number of methods to get around Abbé's diffraction limit using, in parts, very different techniques to usual microscopy. It seems, however, that a resolution of atoms is not achieved yet.]"
 

Polymath257

Think & Care
Staff member
Premium Member
I thought being able to perceive something requires an electron of photon being able to bounce off the material and also something concerning the wavelength of the particle at travel...

Let me try to dig up the physics behind this. To me, it seems not possible to be able to see an atom since we need an electron microscope to view molecules.

In this case, the atom is being bombarded by photons from the lasers and is re-emitting light that we see in the photo. It would not have the precision of an EM, especially with visible light. But, if there is only one atom in the well, that is the one re-emitting the light.
 

Subduction Zone

Veteran Member
I thought being able to perceive something requires an electron of photon being able to bounce off the material and also something concerning the wavelength of the particle at travel...

Let me try to dig up the physics behind this. To me, it seems not possible to be able to see an atom since we need an electron microscope to view molecules.

[Edited]
Here's something from the web:
Is it possible to "see" atoms?

"Now, can we "see" atoms? This depends, as I already hinted at, what you mean by "see". If you mean "make a picture in visible light", then you can't do that. In microscopy, there is a rule of thumb that the smallest things you can distinguish with a perfectly engineered microscope have to have a size about half the wavelength of the light you're shining at it. The more exact version of this is known as the Abbé difraction limit. Visible light has wavelength of about 400-700 nanometres. This is of course about 4000-7000 times as much as the diameter of the atom, so there is indeed no way we can see an atom with a (diffraction) microscope using light. [As suggested in the comments, there are a number of methods to get around Abbé's diffraction limit using, in parts, very different techniques to usual microscopy. It seems, however, that a resolution of atoms is not achieved yet.]"

When I read the article I understood that the atom absorbs and reradiated light photons from a laser beam. In other words the atom is continually being excited, emitting a photon, and then it gets excited again. As a result we do not see the highly directional laser light. We see the light of the photons that are emitted in all directions by the single atom.

ETA: Dang it! Beaten by just a couple of minutes by Polymath. But it is nice to see that my answer was the same as his.
 

suncowiam

Well-Known Member
In this case, the atom is being bombarded by photons from the lasers and is re-emitting light that we see in the photo. It would not have the precision of an EM, especially with visible light. But, if there is only one atom in the well, that is the one re-emitting the light.

When I read the article I understood that the atom absorbs and reradiated light photons from a laser beam. In other words the atom is continually being excited, emitting a photon, and then it gets excited again. As a result we do not see the highly directional laser light. We see the light of the photons that are emitted in all directions by the single atom.

ETA: Dang it! Beaten by just a couple of minutes by Polymath. But it is nice to see that my answer was the same as his.

Ok, that makes sense that the photons are being emitted from the atom. Nice.
 

`mud

Just old
Premium Member
Good for the millions of photons out there,
and of the lasers, and magnets, and.....
 

siti

Well-Known Member
I presume its a picture of the light re-emitted by a positively charged strontium ion when irradiated by the appropriate frequency laser - the radius of a strontium ion is of the order of 10^-10m - about 7 or 8 orders of magnitude smaller than the cross head screw towards the top left and what I'm guessing are probably 1/16th inch stainless steel tubes at the bottom centre...the blue/violet dot in the picture appears to be about 1 or 2 orders of magnitude smaller than these - so roughly about 0.1mm or thereabouts actual diameter so obviously far bigger (by about 6 orders of magnitude) than a single ion/atom...before anyone gets too carried away...still pretty amazing image though.
 

Polymath257

Think & Care
Staff member
Premium Member
I presume its a picture of the light re-emitted by a positively charged strontium ion when irradiated by the appropriate frequency laser - the radius of a strontium ion is of the order of 10^-10m - about 7 or 8 orders of magnitude smaller than the cross head screw towards the top left and what I'm guessing are probably 1/16th inch stainless steel tubes at the bottom centre...the blue/violet dot in the picture appears to be about 1 or 2 orders of magnitude smaller than these - so roughly about 0.1mm or thereabouts actual diameter so obviously far bigger (by about 6 orders of magnitude) than a single ion/atom...before anyone gets too carried away...still pretty amazing image though.


Exactly.
 
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