Posted on 08/05/2021 12:30:47 PM PDT by Red Badger
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 August 6, 2021, 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.
Illustration of NIST’s quantum crystal. Credit: Burrows/JILA
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.
“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.”
Bollinger’s group has been working with the ion crystal for more than a decade. What’s new is the use of a specific type of laser light to entangle the collective motion and spins of a large number of ions, plus what the researchers call a “time reversal” strategy to detect the results.
The experiment benefited from a collaboration with NIST theorist Ana Maria Rey, who works at JILA, a joint institute of NIST and the University of Colorado Boulder. The theory work was critical for understanding the limits of the laboratory setup, offered a new model for understanding the experiment that is valid for large numbers of trapped ions, and demonstrated that the quantum advantage comes from entangling the spin and motion, Bollinger said.
Rey noted that entanglement is beneficial in canceling the ions’ intrinsic quantum noise., However, measuring the entangled quantum state without destroying the information shared between spin and motion is difficult.
“To avoid this issue, John is able to reverse the dynamics and disentangle the spin and the motion after the displacement is applied,” Rey said. “This time reversal decouples the spin and the motion, and now the collective spin itself has the displacement information stored on it, and when we measure the spins we can determine the displacement very precisely. This is neat!”
The researchers used microwaves to produce desired values of the spins. Ions can be spin up (often envisioned as an arrow pointing up), spin down or other angles, including both at the same time, a special quantum state. In this experiment the ions all had the same spin — first spin up and then horizontal — so when excited they rotated together in a pattern characteristic of spinning tops.
Crossed laser beams, with a difference in frequency that was nearly the same as the motion, were used to entangle the collective spin with the motion. The crystal was then vibrationally excited. The same lasers and microwaves were used to undo the entanglement. To determine how much the crystal moved, researchers measured the ions’ spin level of fluorescence (spin up scatters light, spin down is dark).
In the future, increasing the number of ions to 100,000 by making 3D crystals is expected to improve the sensing capability thirtyfold. In addition, the stability of the crystal’s excited motion might be improved, which would enhance the time reversal process and the precision of the results.
“If we are able to improve this aspect, this experiment can become a fundamental resource for detecting dark matter,” Rey said. “We know 85% of the matter in the universe is made of dark matter, but to date we do not know what dark matter is made of. This experiment could allow us in the future to unveil this mystery.”
Co-authors included researchers from the University of Oklahoma. This work is supported in part by the U.S. Department of Energy, Air Force Office of Scientific Research, Defense Advanced Research Projects Agency, Army Research Office and National Science Foundation.
Reference: “Quantum-enhanced sensing of displacements and electric fields with two-dimensional trapped-ion crystals” by K.A. Gilmore, M. Affolter, R.J. Lewis-Swan, D. Barberena, E. Jordan, A.M. Rey and J.J. Bollinger., 5 August 2021, Science. DOI: 10.1126/science.abi5226
Do not touch.....................
Ah-
Red Matter
About 20 or so years ago, maybe more, I read that NIST was working of an electrical standard for MASS using a giant coil as an electro-magnet.....
I wonder if they ever succeeded?...................
ah, dark matter. That thing that was invented out of whole cloth to make the numbers work so the big bang can hold together as a theory....We have been looking for the “missing matter” ever since then...why, that’s it, it must be “dark matter” that we cannot see!
So now we have our new super sensitive detector - and if we detect any disturbance in the EM force, why that’s GOT to be chalked up to dark matter.
And they say religion requires faith..
In order to redefine the kilogram, a change that will be implimented on May 20, 2019, the General Conference on Weights and Measures required at least three experiments to calculate the Planck constant to an uncertainty of no more than 50 parts per billion, one of which must calculate the value to within an uncertainty of 20 parts per billion.
The international silicon sphere effort has become precise enough to achieve an uncertainty of only 10 parts per billion, and four Kibble balance measurements also produced values within the required uncertainty.
And as a result of all these measures, much more than the kilogram is about to change.
The New International System of Units
More than redefining the kilogram, the 26th meeting of the General Conference on Weights and Measures (CGPM) is setting a fixed value for the Planck constant, and as a result, enacting the largest transformation of the International System of Units since its inception in 1960.
Previously, Planck’s constant was measured incessantly, averaged with other measurements across the world, and a list of new values was delivered to research institutions every few years.
“No one will measure the Planck constant once this [vote] has passed, because its value will have been defined,” Davis says.
In addition to the Planck constant, the Avogadro constant will be set at a fixed value, as will the elementary charge (e, the charge of one proton), and the triple point of water (the temperature at which water can exist as a solid, liquid or gas, to be defined as 273.16 degrees Kelvin, or 0.01 degrees C).
By setting the Planck constant as an absolute value, scientists are turning away from conventional mechanical measurements and adopting a suite of quantum electrical measurements to define our fundamental units. Once the constant is defined, it can be used to calculate a range of masses from the atomic level to the cosmic, leaving behind the need to scale the IPK down into smaller measurable parts, or up to enormous masses.
dark matter matters
About the only thing they didn’t mention was finding the usual missing sock and/or Jimmy Hoffa...
Although it is disappointing that it won’t allow direct experimental verification of other fake science like string theory, super-string theory, beauty, or the multiverse...
Ahh... Those halcyon days of scrambling around during either grant renewal time or the federal budget-cycle preparation...
Both of those are the principal drivers of fundamental research ideas over these past 60-years...
What they mean by “time reversal” is that the effect would precede the cause. Sorry, that is not logical. Before and after is defined by cause and effect.
Humans cannot step out of the cause-effect continuum. Only God is outside that continuum, and is not bound by time, or a rigid cause-effect sequence.
So, the Planck constant is finally constant!.............Thank you!...............
BS!
It could be a dark matter sensor... if dark matter were more than just a mathematical construct to fill in a question mark to make faulty equations balance.
They need to fix the theory before making up more fairy tales.
At the quantum level, there is no discernable information difference between past events and future events.
For the Faithful... the quantum part of our Reality IS God.
LOL... Perfect. :-)
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