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Space Science

Scientists Created a Quantum Crystal That Could Be a New Dark Matter Sensor (phys.org) 58

Posted by BeauHD from the hide-and-seek dept.
fahrbot-bot shares a report from Phys.Org: Physicists at the National Institute of Standards and Technology (NIST) have linked together, or "entangled," the mechanical motion and electronic properties of a tiny blue crystal, giving it a quantum edge in measuring electric fields with record sensitivity that may enhance understanding of the universe. The quantum sensor consists of 150 beryllium ions (electrically charged atoms) confined in a magnetic field, so they self-arrange into a flat 2D crystal just 200 millionths of a meter in diameter. Quantum sensors such as this have the potential to detect signals from dark matter -- a mysterious substance that might turn out to be, among other theories, subatomic particles that interact with normal matter through a weak electromagnetic field. The presence of dark matter could cause the crystal to wiggle in telltale ways, revealed by collective changes among the crystal's ions in one of their electronic properties, known as spin.

As described in the Aug. 6 issue of Science, researchers can measure the vibrational excitation of the crystal -- the flat plane moving up and down like the head of a drum -- by monitoring changes in the collective spin. Measuring the spin indicates the extent of the vibrational excitation, referred to as displacement. This sensor can measure external electric fields that have the same vibration frequency as the crystal with more than 10 times the sensitivity of any previously demonstrated atomic sensor. (Technically, the sensor can measure 240 nanovolts per meter in one second.) In the experiments, researchers apply a weak electric field to excite and test the crystal sensor. A dark matter search would look for such a signal.
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Scientists Created a Quantum Crystal That Could Be a New Dark Matter Sensor More

Scientists Created a Quantum Crystal That Could Be a New Dark Matter Sensor

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  • The Skeksis are coming (Score:3, Funny)

    by crowne ( 1375197 ) on Friday August 06, 2021 @03:18AM (#61662539) Homepage
    https://en.wikipedia.org/wiki/... [wikipedia.org]
  • maybe a dumb question, but is millionth of a millimeter really the standard way to measure this? wouldn't 1/5000th or 2/10000th be better?
    • Milli, micro, nano, pico are fine too
    • Comment removed based on user account deletion

      • Re: (Score:1)

        by rtb61 ( 674572 )
        Just use iron shavings, quantum particles field flows stand right out, there called magnetic fields, magic energy rather than logical quantum particle field flows. They have an explanation but are being wilfully blind to end because it makes them fell uncomfortable. Explains why light is both particle and wave, although the wave in quantum particle terms are particles as well just not in normal space terms.
    • It's NIST - everyone there uses SI units.. A millionth of a millimeter is a nanometer.

      I'm guessing that in the interview, the NIST rep gave the journalist information in terms of nanometers, then the journalist assumed that their readers wouldn't know what a nanometer was, so rephrased all the quotes as millionths of a millimeter thinking that was somehow more useful.

    • "200 millionths of a meter in diameter" to be precise. ie: 31416
      square micron for a 150 atom 2D crystal!

  • Last week, google turned a quantum computer into a time crystal. Simulated? No, when you play at this level your computer itself turns into interesting physical systems. Now here you have a quantum computer, like many, that can be disrupted by noise, but only a strange particular kind of noise that could be dark matter, so an exotic sensor.

    Bottom line? When you come up with a paradigm of computing expressive enough to frame almost any physical process as a computation, computer science gets *really* interes

    • Quantum is as you say the more beautiful blurred boundary between physics and computing.

      However, I think a relative area to ponder is about the total system. The crystals state is being induced and then measured. All the electronics hooked up to it we can easily assume follow a traditional computer model. So as we create more systems with quantum computing, the question seems to be will you ever have a pure quantum computer? What about a quantum database? Maybe quantum computers will always be bound to a do

      • Good question. Another is, do we need to care? there may be hybrid systems (eg optical systems that leverage just some photon quantum behavior) that rock the world, and reveal that our hope for pure quantum computation imposes too much classicality on poor old dice playing God. I am open for anything!

    • Re: (Score:1)

      by shoor ( 33382 )

      I didn't read the article itself, just the summary. It didn't mention computing at all, just quantum states for measurement.

  • Which of these mentioned theories say that DM "interact[s] with normal matter" in any way at all? I thought the whole idea was that it didn't interact with normal matter. How many shades of dark matter are there?

    • It's dark because it's undetectable in any spectrum of light. However it's strongly believes to be a large amount of the universes total matter because the shapes of galaxies cannot not be accurately simulated without supposing it's exist. This very conclusion dictates it does have an interaction that is relative to gravity. This is why we have two terms for "dark matter" and "dark energy". I am not an expert on this not do I fully understand the weak EM force at play here, enough to understand why the sens

      • The big question is whether a spacecraft and its occupants would develop random holes when flying through dark matter.

        • Re: (Score:3)

          by MrL0G1C ( 867445 )

          I'm guessing the answer is no because our solar system also contains dark matter. But dark matter is distributed very thinly AFAIK, it doesn't clump like ordinary matter.

          Since matter clumps and dark matter doesn't, I think ordinary matter is orders or magnitude more dangerous to spaceships.

          I could be wrong, ask an alien.

          • This seems to be the conclusion for sub FTL but once we consider FTL hypotheses (I think calling them theories is too strong), then I think the question again is raised about how dark matter may react.

      • Re: not so dark matter (Score:5, Informative)

        by Sique ( 173459 ) on Friday August 06, 2021 @05:36AM (#61662761) Homepage
        Dark Matter and Dark Energy are very different concepts and fill quite different holes in our theories. Dark Matter was first postulated by Fritz Zwicky in the 30ies of the 20th century, when he noticed the clustering of galaxies. Later the rotation of galaxies was another hint at the existence of more matter than the one detected by their electromagnetic waves. Now also the small disparities in the Cosmic Microwave Background and the simulations trying to recreate the development of the Universe point to Dark Matter.

        Dark Energy in turn is needed to explain why the expansion of the Universe is accelerating, when it was slowing down until some billion years ago. But the models fit the observation if you introduce a force counteracting Gravity that is proportional to the volume to the Universe, which means that it grows with further expansion and even accelerates it when it outweighs the mass in the Universe.

        • Interesting. I didn't know Dark Energy was the necessary energy to fit the observations of an Accelerating Universe. I also thought Einstein's math had a variable which he originally thought was zero (so unnecessary) and that this variable adequately makes the model work. It sounds like you are saying we have to use Einstein's work for two different periods of the universe, one where acceleration is slowing and then another for where it's accelerating? So is Dark Energy simply a name for this variable in th

          • Re: (Score:2)

            by Sique ( 173459 )
            It's actually a constant called Lambda, which was introduced by Albert Einstein. If it is zero, the Universe would collapse under its own mass, as the gravity pulls it together. If it is small but positive, it exactly counterweighs the mass of the universe, and we have the Steady State Universe as imagined by Albert Einstein and Fred Boyle.

            As I wrote, Dark Energy is thought to be proportional to Volume, and Energy per Volume has the same unit as Force per Area, which is pressure. You can imagine Dark Ener

    • Re:not so dark matter (Score:5, Interesting)

      by Required Snark ( 1702878 ) on Friday August 06, 2021 @05:45AM (#61662777)
      So called dark matter has been detected by it's gravitational interaction with non-dark visible matter. So far these interactions have been observed at galactic scale [wikipedia.org] or larger.

      Two other kinds of dark matter detection are being tried. Direct detectors [wikipedia.org] look for interactions between dark matter and atoms while indirect detectors [wikipedia.org] look for signals from possible dark matter candidates. Some models predict that dark matter can decay or be annihilated producing detectable particles like gamma rays, and searches for these signals are currently being done.

      • Specifically regarding direct interactions with matter, in addition to gravitation interaction, it is possible that dark matter would interact by exchange of either Weak or Higgs bosons. For the most vanilla kind of dark matter you can imagine, Weak interactions have been ruled out experimentally for at least a decade. However Higgs exchange has not yet been ruled out. It is particularly compelling, because coupling to the Higgs field is what gives rise to inertial mass. So you have to come up with fairly

      • Re: (Score:1)

        by sglines ( 543315 )

        Except that we don't have a clue what Dark Matter is so we have no idea how to detect it other than observing its effect on non-data objects. So far it only manifests itself as fields of gravity that distorts visible light.

    • Normal, baryonic matter not all matter. Dark matter also does not react with light but does react with gravity.
    • How many shades of dark matter? As many as the plot requires. Its like the sonic screwdriver of cosmology, it is exactly what you need, in exactly the amount you need, located exactly where you need, and with the exact properties you need in order to patch any gaping hole in a theory to make it seem less nonsensical.

    • We don't know what dark matter is. There are many hypotheses for what it might be. They range from the "fairly normal" like primordial black holes, to the very exotic like entirely new classes of particles. Whenever someone talks about a "dark matter detector", they really mean a detector for some hypothesized type of object that might or might not be what dark matter actually consists of. From the article,

      "Ion crystals could detect certain types of dark matter--examples are axions and hidden photons--that interact with normal matter through a weak electric field," NIST senior author John Bollinger said. "The dark matter forms a background signal with an oscillation frequency that depends on the mass of the dark matter particle. Experiments searching for this type of dark matter have been ongoing for more than a decade with superconducting circuits. The motion of trapped ions provides sensitivity over a different range of frequencies."

  • ... if you were to embed these crystals in a sword, it would glow blue in the presence of orcs.
  • Blue crystal, interacting with mysterious fields? I've seen that before. http://doctorwhoworlduk.com/me... [doctorwhoworlduk.com]

  • Could be. Probably isn't.

  • ... to detect dark matter. Something that constitutes 85% of the matter in the universe should have significant effects on orbits of planets and other bodies. There would be no way for us to launch probes like the Voyager series and have them fly by outer planets without the ability to compensate for DM gravitational effects.

    Pluto was discovered by tiny perturbations in the orbit of Neptune. Pluto is tiny.

    • Observing the effects of dark matter on stellar orbits, and indeed on the evolution of the entire universe (both in the density perturbations visible in the cosmic microwave background and density fluctuations in groupings of galactic clusters) is how we came up with the 85% number in the first place. But directly detecting it is different story. People knew the moon existed for thousands of years, but it wasn't until we landed on it that we could claim to have direct detection evidence.

      As for things like

      • People knew the moon existed for thousands of years, but it wasn't until we landed on it that we could claim to have direct detection evidence. [emphasis mine]

        I don't think that is a reasonable standard for "direct detection evidence".

        • Re: (Score:2)

          by PPH ( 736903 )
          It is if you are blind.

        • it's the standard that dark matter detection is held to, though. Interaction with a terrestrial detector though non-optical means. You can observe the moon's effect on tides, just as you can observe dark matter's effect on stellar rotation.

      • Re: (Score:2)

        by PPH ( 736903 )

        the dark matter density is uniform throughout the solar system and beyond

        Now you are getting into issues of gravity and scale invariance. It doesn't take much of a gradient (parts per million or billion) to be easily detectable across planetary distances. But we don't see that. Now, zoom out to galactic distances and the effects are completely different. Gravity is (assumed to be) scale invariant. So an orbit of the ISS around the Earth looks just like the orbit of Jupiter around the Sun. But if you zoom out further to galactic distances, this is no longer the case. So we invent

        • Obligatory xkcd: https://xkcd.com/1758/ [xkcd.com]

          People have been trying to come up with a consistent modified gravity theory for decades and none of them fit the experimental evidence. On the other hand, your comment that DM has a uniform density at some scales, but not others, is technically true but incredibly misleading. The atmosphere has mostly uniform density on small scales, but in particular the density goes down as you go higher in altitude, i.e. away from the local gravity well. Dark matter density dro

          • Re: (Score:2)

            by PPH ( 736903 )

            The atmosphere has mostly uniform density on small scales, but in particular the density goes down as you go higher in altitude,

            Actually I have a watch that can figure out which floor of my house I'm on. It's a matter of achieving the requisite sensitivity of the instrumentation/experiment.

            We can model the effects of classical galactic gravity on the distribution of orbits of comets. No DM required.

  • "We might be able to detect something we don't even exists and don't understand in the slightest!" May as well say it can let you count how many angels can dance on the head of a pin.

    • Physics has advanced largely by postulating the existence of as-yet unobserved particles and forces and designing experiments to detect them. Relativistic shifts in Mercury's orbit, weak bosons, the Higgs bosons, gravitational waves; we didn't "know" any of them existed before they were detected.

      • And most of those were only written about in esoteric physics journals until after they had been confirmed.

        My problem isn't with physicists postulating things. My problem is parading postulation around in public as if it were, if not fact, a near certainty.

  • What would ever they do if it read zero, everywhere? Ah well you know what would happen - the theory would suddenly become much more complex with many more 'fundamental constants', ANYTHING necessary to delay the conclusion that dark matter is an illusion until well after the current generation of scientists who have based their careers on the existence of dark matter are retired. But technologists will find that certain equations and theories which operate outside of the dark matter theory are 'predictive

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