Photographed: The Glow from a Single, Hovering Strontium Atom

By Carl Engelking | February 14, 2018 12:56 pm

That pale blue dot in between two metal electrodes is a single strontium atom. (Credit: David Nadlinger)

In the photo above, you’re looking at a single, positively charged strontium atom suspended by electric fields.

It’s an atom, visible to the naked eye.

Whoa, right?

David Nadlinger, a quantum physicist and PhD candidate at Oxford University, is the person who put it all together. He titled his picture “Single Atom in an Ion Trap.” A blue-violet laser blasts the atom, which then absorbs and re-emits enough light particles to be photographed with conventional equipment. So, technically, you’re seeing light emitted from an atom and not the atom itself. Two metal electrodes generate electric fields that hold the atom nearly motionless. For perspective, the space between the two metal forks is roughly 2 millimeters.

The photograph was worthy of the grand prize in a national photo contest organized by the United Kingdom’s Engineering and Physical Sciences Research Council (EPSRC). Nadlinger captured the image using a Canon 5D Mark II DSLR, a Canon EF 50mm f/1.8 lens, extension tubes and two flash units with color gels. Here’s the entire, award-winning photograph:


The award-winning photo. (Credit: David Nadlinger)

“The idea of being able to see a single atom with the naked eye had struck me as a wonderfully direct and visceral bridge between the miniscule quantum world and our macroscopic reality,” Nadlinger told EPSRC. “A back-of-the-envelope calculation showed the numbers to be on my side, and when I set off to the lab with camera and tripods one quiet Sunday afternoon, I was rewarded with this particular picture of a small, pale blue dot.”

It may not be planet Earth, but my guess is Carl Sagan would have no problem with Nadlinger’s new twist on an iconic “pale blue dot.”

CATEGORIZED UNDER: Space & Physics, top posts
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  • Larry Hermann

    The suggestion this blue dot is an atom (or the light reflected off it) is not plausible. Not when the scale between the two needles is 2 mm. That’s millimetres (10 to the power of minus 3). Atoms are at the femtometre scale ( 10 to the power of minus 15 ). No way could an atom be resolved when looking at a 2 mm gap. Now it is possible that an incredibly large (relative to the atom) plume of gas surrounding an atom could show up at this scale but certainly not a single atom. Someone is not being entirely honest here

    • Richard Colbert

      Not being a scientist; but hopefully having some common sense; what you say seems to be more than reasonable. So, I read this in another article that quoted a section from the ‘EPSRC’…”When illuminated by a laser of the right blue-violet colour the atom absorbs and re-emits light particles sufficiently quickly for an ordinary camera to capture it in a long exposure photograph.” This seems to confirm what you posit. We are seeing light particles (or plume of gas?) and not the actual atom.

      • pjchooch

        Think of it as turning an atom into an LED.

    • Gary S

      It’s printed in the article..”So, technically, you’re seeing light emitted from an atom and not the atom itself.”

      • Michael Cleveland

        All things are visible as reflected or emitted light, but his claim to have photographed an atom is comparable to photographing Jupiter and saying it’s the same as the grain of sand in the palm of my hand. Sorry, doesn’t fly.

    • Dirk Muehlner

      This is pretty silly. When you look at star photos the images of the stars are FAR larger than they would be if they were resolved. Do you claim these are not images of stars? And whenever we see anything at all you could claim we are not seeing the thing but rather light scattered from or emitted by it. But that’s what seeing is.

    • White Elk Clearwater

      Why is it that so many people make such great efforts to tear someone else down?!
      Even willing to misquote etc to do it.
      Does it make them feel “big” by knocking someone else?

      *** READ AGAIN CAREFULLY WITHOUT the prejudicial desire to berate. David Nadlinger man did NOT say in the article that what we see is the atom itself. He DID say that it is light waves emitted from the atom while being suspended in the electromagnetic bottle & being bombarded by specific light waves.
      This gives us an image of the existence of that single atom in its captivity. That’s all he said no more & no less.

      • Larry Hermann

        Hi White,

        I don’t believe anyone (including myself) is trying to tear someone down. I’ve outlined my reasons for being somewhat skeptical but I’ve also asked for any physicist to please better explain how photons of light coming off a single atom could go from the 10 to the minus 15 to the 10 to the minus 3 orders without any magnification process and be seen by the naked eye. I don’t believe it’s unreasonable to be questioning this. I’m always receptive to learn. If there’s a convincing explanation i’m all ears.

        Carl Sagan (1996), said, “. . . at the heart of science is an essential balance between two seemingly contradictory attitudes—an openness to new ideas, no matter how bizarre or counterintuitive, and the most ruthlessly sceptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.”


        • White Elk Clearwater

          Okay that’s a clearer & more positive question Larry.
          Try this example. A LED’s actual light emitting is small but it can give off much more light than its size & the size of its “spark” would seem reasonable.

        • teknowh0re

          Yes, yes you were trying to, and worse, you dont know what youre talking about and didn’t even look into the process used to create the photo.

          • Larry Hermann

            Hi teknowh0re,

            I’d long forgotten about this discussion which was eight months ago. But just to re-iterate. I outlined some reasoning why I had been skeptical of this claim. I also clearly declared I am no authority on this matter, far from it, as my qualifications are as a psychiatrist, not a physicist. I then asked if any physicists could help to clarify this.

            So no I disagree with your ‘yes, yes you were trying to’. The suggestion being I was ‘tearing someone down’. It is legitimate to question things or claims and be skeptical without being accused of ad hominem attacks.

            And I also disagree it is ‘worse’ I don’t apparently know what I’m talking about because I have never made a claim I do know what I’m talking about in any definitive way. I’ve questioned something AND I’ve asked for any physicists to please clarify.

            I have read your other recent post which mentions among other things including technical explanations: ‘……The apparent size you see in the picture is what we’d call optical aberration’. Who’s “we”? And what are your qualifications so I can better contextualise your technical explanations.



        • dirtside

          So, let’s consider the objects (ostensibly) in play here: a single strontium atom, and a digital camera with a finite resolution. The strontium atom is continually being energized, and keeps emitting photons. Some of those photons pass through the camera’s lens and end up striking one particular pixel of the camera’s CCD, over and over enough to build up (over the course of the exposure) a tiny blue dot. Depending on the CCD’s resolution, how long the exposure is, and how frequent the photons, it seems possible that you could end up with an image that has one pixel indicating the presence of the photon emissions from a single atom.

      • Michael Cleveland

        The headline has been modified since this first appeared. It originally stated that he had succeeded in photographing a single atom. Too bad the editor was out to lunch when this was being published–oops, he’s a blogger, doesn’t answer to editors. Also note that the article continues to state that you are looking at an atom.

        • White Elk Clearwater

          good! The article also points out that technically you are seeing light blurted out by the atom. Sloppy writing. The editors should review bloggers

          • Kieran Latty

            When you see a star or any hot body you are seeing light similarly ‘blurted out’ by the object. In other cases the light is reflected from some other light source (as in the case of the moon) but both count as ‘seeing’ the object.

        • teknowh0re

          It IS a photo of a single atom. Its a single atom reEMITTING photons of laser light.

      • John Weaver

        Why don’t you answer your own question White. You’re basically knocking his response, which is what you called him out for doing. So does it make you feel “big” to do exactly what you criticize him for doing?

    • Bill Mayberry

      As the article points out, light is NOT “reflected off” the atom. It is loaded with a laser then rids itself of that energy with a light burst. That burst diameter is easily well withing visible ranges.

    • Horváth M. Sándor

      It’s you who’s not honest.

    • Aaron Bannister

      The blue dot is the camera’s view of the atom. Yes, the atom is far too small to be resolvable by the camera. However, if it’s light is bright enough against the background, then the single pixel aimed at the region of space containing the atom will receive more light than its neighbors, leading to the bright spot. You couldn’t use this image to get a precise measurement of the location of the atom, but that’s not the point here. The point is to get a single atom to emit enough light that it is distinguishable against a background with a normal camera.

    • teknowh0re

      First, its a strontium atom, which is a large atom, but still tiny. Also: “When bathed in a specific wavelength of blue light, strontium creates a glow hundreds of times wider than the radius of the atom itself (which is about a quarter of a nanometer, or 2.5×10 to the -7 meters. This glow would be barely perceptible with the naked eye but becomes apparent with a little camera magic”
      “The apparent size you see in the picture is what we’d call optical aberration,” Nadlinger said. “The lens we’re seeing it through is not perfect — also it’s slightly out of focus and slightly overexposed. You could compare it to looking at the stars in the night sky, which appear bright but are actually much, much smaller than the size they seem to be, just because our eyes (or the camera) don’t have enough resolution to process them.”

    • thinkdunson

      i think i have an explanation. i’m no physicist, but it makes sense to me…
      they’re able to suspend a single atom between those electrodes. they send light towards it. in the rare chance that a photon happens to get sent directly at the atom, it bounces off it, but not at the exact same angle every time. since there are so many photons, ‘rare’ is still enough to see that spread of reflected light.

  • Jordi Heguilor

    Eyeballing, the atom’s size seems about 1/10 the distance of the two electrodes. Now, since such distance is 2mm, that would make for a really huge atom.

    Sorry, I did not read the post below me.

    • Uncle Al

      The atom is is pumping out photons in 4(pi) steradian random directions. Not watts, photons. Intensity drops as the square of the radius. Lightspeed is a foot/nanosecond. Twinkle, twinkle little atom. The camera integrates cumulative intensity during the exposure interval. Longer exposure, larger “atom.”

      If it were a Rydberg atom, it could be huge. The n = 137 state of hydrogen has an atomic radius ~1 µm.

      • I MD

        No matter what justification you make, you are experiencing the output of the atom, not the atom itself. Yes I’d agree to the point – analogous to a star as an example

  • Jamie

    I dont understand the objections to what we are seeing. We always see light emitted or bouncing off something. Seems like he is doing it correctly. Good job!

    • Larry Hermann

      Hi Jamie, I’m no physicist myself. I’m a psychiatrist by profession so disclaimer of course to any physicist authority on this matter! Though I have had longstanding interest in various sciences. Btw psychiatry is stuffed full of non-scientific nonsense so I’m always wary of other scientific claims too. All previous demonstrations of atoms being captured on film that i’ve ever seen have been via electron microscopes. A very different and realistic proposition compared to this one that light bouncing off an atom (which is incredibly small obviously) could be seen by the naked eye. Would be very interested to hear from any physicists who could throw any more light (pardon the pun) on this issue. cheers

      • Jamie

        Well said Larry. Now I understand. One would think that only a single or a tiny number of photons would actually bounce from an impact with a single atom. So he must have a photon multiplier of some sort in that electric field.

        Then again, photons are reflecting from single atom impacts all around us all the time. Every surface is a matrix of single atoms.

        And even weirder is this question. How do we know there is a single atom there? I thought quantum mechanics is all about probability.

  • Ken Albertsen

    Nice shot! Science and nature are infinately awesome. No need for myths, religion or metaphysics.

  • Dee Gee

    Seems to me that photo parameters are omitting wavelength of the light and its power and time after the light pulse, because the phenomena is not continues, if it is, then we have single atom LED ?

  • dennis7979

    absolutely amazing

  • Robert Adams

    Phil Morrison showed the same thing in the ’80s in his video series “The Ring of Truth” (Atoms) He might used a barium atom.

  • Erik Bosma

    I don’t understand why this article is causing so much discontent. Think of this: Can you see an LCD bulb from, say, 100 metres? Of course not, but if it’s switched on and emitting photons it can easily be seen from that distance. Plus, allow me to digress, our eyes are very sensitive and can spot sources of light that are not much more than a few photons.

    • Michael Cleveland

      The point is that the image shown is to an atom as Jupiter is to a grain of sand. It’s not a photograph of an atom, but of the effect of that atom on its surroundings.

  • Cees Timmerman

    The thinnest human hair is 1.7e-5 m wide. A strontium atom is 2.55e-10 m wide. Assuming that’s vacuum, that’s a pretty large reflection for a single atom.


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