Like Sassy Teenagers, Atoms Talk Back

Sep 15, 2014

By Loren Grush

If you talk to an artificial atom, it turns out the atom will say something back to you. Unfortunately, you won’t be able to hear it.

Researchers at Chalmers University of Technology in Sweden have communicated with an artificial atom in a lab. When they fed their atom extremely high frequency sound energy, the atom regurgitated the energy back to them in the form of sound waves. The researchers were then able to record these auditory rumblings with high-tech audio equipment, as the sounds were too high to be heard by human ears.

This absorption/emission interaction is very similar to how atoms interact with light. When a photon of light gets close enough to an atom, sometimes the atom will gobble it up, absorbing the photon into its body. However, atoms aren’t very good at holding this energy for long, so they usually spit it back out in the form of a light particle.

This concept has been extensively studied in the field of quantum optics, but it’s the first time scientists have demonstrated such an interaction between artificial atoms and sound. Their study, published in the journal Science, provides researchers with a better understanding of the laws of quantum physics, which they hope to harness one day for making extremely fast computers.

18 comments on “Like Sassy Teenagers, Atoms Talk Back

  • . is very similar to how atoms interact with light. When a photon of light gets close enough to an atom, sometimes the atom will gobble it up, absorbing the photon into its body.

    From the point of view of the humble lay-person….where does it go?



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  • From the point of view of the humble lay-person….where does it go?

    The photon merges with one of the atom’s electrons. That electron’s energy then increases by the energy of the photon. This causes the quantum numbers of the electron to change. (In classical terms, its orbit becomes wider and its angular momentum is modified. In quantum terms, there is no exact orbit, but the mean reciprocal of the orbital radius changes.) Later the electron produces a photon equal to the energy difference, thereby returning to its previous state. This new photon is then emitted from the atom; that’s why the energy isn’t held long.



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  • 6
    NearlyNakedApe says:

    I find this article to be very badly written. By trying to “dumb down” the common quantum light absorbtion and reemission process by electrons into “easy” language, the author actually makes it confusing and harder to grasp for laypeople.

    When a photon of light gets close enough to an atom, sometimes the atom will gobble it up, absorbing the photon into its body. However, atoms aren’t very good at holding this energy for long, so they usually spit it back out in the form of a light particle.

    A photon IS a light particle. This sentence kind of makes it sound like the “atom” (actually the electron) spits out a different type of particle than the one it absorbed. Why not just say “it spits out a NEW photon”?



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  • From the point of view of the humble lay-person….where does it go?

    Nitya. I’ve been aware of Quantum Mechanics for years and always thought I could only understand a bit of fluff around the outside. After reading a few books, I kinda got my head around Relativity, so I said an expletive to myself, and bought Jim Al Khalili’s book Quantum and dove head first into uncertainty. Written for the physics challenged amateur like me, and I think I got most of it. I certainly understand what Jos Gibbons just wrote above. So I commend the book to you.

    Sneaky things photons. They’re shy. The moment you look at one, it changes. Which invokes the term Quantum weirdness.



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  • I concur. The type of people that would select this article as something to read, would probably have a science bent already, so, like you, would be annoyed at the journalist for using Fox News Speak for the lowest common reader. Might I modestly suggest:-

    When a photon of light nears an atom, an electron in the atoms’ electron cloud will sometimes absorb the photon’s energy, raising the electron to a higher unstable energy state. The electron on returning to its more stable lower energy state, emits a photon of the same energy as that of the incoming photon.

    Not as correct or in depth as Jos Gibbon’s above, but certainly more readable that the Fox Speak.



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  • For some reason my comment did not pass, so I shall repeated it.
    You are apsolutely right NearlyNakedApe. I am also confused how can there be an artificial atom? Is that than an isotope?

    However, atoms aren’t very good at holding this energy for long, so
    they usually spit it back out in the form of a light particle.

    I tought that atoms always “spit” one electron when they gaine one, by its nature, because of the first law of thermodynamics (preservation of energy). How can that be taking? They do what they do because of its nature, and that is transformation of energy. I am confused.



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  • . David. “You know, I couldn’t do it. I couldn’t reduce it to the freshman level. That means we really don’t understand it.”

    I’m aware of this Feynman quote, so I assume that I don’t really understand it simply because I think I do. I’ve had it explained, seen diagrams and watched simulations of the double slit experiment and representations of those particles appearing simultaneously in two places at once. Haven’t read a book about it yet, but it’s obviously a difficult concept.
    Even thinking about light as discrete packages that can be gobbled up and then spat out is mind boggling!



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  • NearlyNakedApe Sep 15, 2014 at 7:53 pm

    A photon IS a light particle. This sentence kind of makes it sound like the “atom” (actually the electron) spits out a different type of particle than the one it absorbed. Why not just say “it spits out a NEW photon”?

    While a photon is often described as “a particle” and has some properties of a “particle”, it also has properties of a wave and can be considered as an “energy package”. It is not a “standard energy package”, and as I understand it, high energy photons can split into two or more lower energy photons.

    Also their “travelling at the speed of light” is when they are in open space.

    http://www.fromquarkstoquasars.com/a-photons-journey-through-the-sun/

    The photons that comprise the sunlight that’s hitting you at this very moment, has spent the past 8 minutes, and 20 seconds travelling from the sun’s surface all the way to your windowsill (or wherever you happen to be)– a journey of a staggering 92,960,000 miles (149,600,000 km). But that’s not the whole story.
    Those photons embarked on a journey that began in the core of our parent star, and they spent a considerable amount of their tenuous little life-spans trying to break free of the sun’s successive layers, before finally emerging from the sun’s photosphere.

    .. . . . .

    After their inception, the photons must travel through the sun’s layers. They start at the core, then move to the radiative zone (the thick layer where the sun generates x-rays and ultraviolet radiation, and where most of the collisions occur), then the convective zone (where the heat is transferred through the sun by convection), to finally the photosphere. This process is estimated to take anywhere between 100,000 to 50 million years to complete.

    Observed sound waves have also been mapped showing the internal structure of the Sun.

    http://astrobites.org/2014/06/02/the-sun-a-gravitational-wave-detector/

    Sound waves occur naturally in stars as a consequence of turbulent convection. They can be observed and indeed have been with satellites such as SOHO (looking at the Sun) and COROT and Kepler (for other sun-like stars). When gravitational waves pass through a star, they also excite sound waves that propagate through it. Sound waves produced by both sources can be measured by making maps of the velocities of rising and sinking blobs of gas on the surface of the Sun (these maps are called Dopplergrams).



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  • Reading some of these comments made me smile. I picked up a book a few days ago called Quantum Computing: A Gentle Introduction. So far I’m on page 12 and if this is “gentle” I would hate to see the hard version. I always had trouble with second order differential equations. The basic calculus I can do but as soon as I see those eigenvectors my math anxiety begins to go into overdrive. It didn’t help that the one course I took on it had an absolutely abysmal teacher. She could barely speak English and she used to lecture by talking softly to the board as she wrote incredibly dense equations on it. It was a struggle to stay awake (it didn’t help that I was working nights at the time). But I’m digressing, if anyone knows of a good book or online class on this kind of math please post a comment.



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  • Do you want just quantum mechanics, or quantum computing too? In the former case, this free-online book is good. In the latter case, you’d need to first familiarise yourself with quantum mechanics, e.g. with that book. After that you can read something on “quantum computing” or “quantum information”, e.g. this. Googling “lecture notes” usually works wonders. If you take to this mathematics but want an extra challenge, you can see how relativity can be taken into account. The lecture notes we used are especially useful.

    However, if what you actually wanted explaining was solving the differential equations themselves, here are two Wikipedia articles that will be a good start. After that you’ll have a clearer idea what references, other articles etc. you wish to read next.



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  • I have yet to read the article on ‘Quantum Weirdness’ in this week’s edition of the New Scientist. I imagine that I’m going to have to do some serious brain stretching, but it might help.
    It worries me when I think that I understand, because it’s obvious that I’m missing something vital.



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  • It’s so much easier to think of light in terms of waves. The concept of ‘photon’ is a bigger stretch of the imagination. I think it’s just one of those concepts in which I just have to take it on ‘faith’ and accept the explanations of the experts. There are many such examples!



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  • Firstly, you’re confusing electrons with photons. Long-terms changes in electron numbers due to chemical reactions last until the next reaction. Secondly, absorbing energy without subsequently releasing it doesn’t violate energy conservation; it just increases the atom’s total energy while reducing how much energy is outside the atom by the same amount. The reason the energy is re-released is because a process that returns the atom to its “ground state” (lowest energy state) is energetically favoured. Indeed, for many atoms absorbing many photons, in thermal equilibrium higher energy states are exponentially rare.



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  • Jos wrote: Do you want just quantum mechanics, or quantum computing too?…

    I was mostly wondering about the differential equations. I tried taking an online class on quantum mechanics but just found without a solid foundation of the math I couldn’t follow it and the same for the quantum computing book. I’ll check out those links you left above. Thanks.



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  • Hm.

    Sound is a different kind of “wave” than light. Particularly, sound waves are made of ordinary matter vibrating. Ie, atoms, or, even more precisely, molecules, vibrating. Am I the only one who wonders exactly how an individual atom would be able to register sound waves, except by moving along with them?



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