Ben Norton and supervisor David Kielpinski, of Griffith University's Centre for Quantum Dynamics in Australia, developed new techniques to capture an atom, which is about 400th billionths of a meter across. The research areas of the Centre include attosecond science, atomic and molecular dynamics in ultrafast fields, atom optics, quantum optics, quantum information and computation, and fundamental quantum mechanics. The team also took the first-ever image of the shadow of a single atom, at their smallest, are only one tenth of a millionth of a millimetre across.
Norton has captured the highest resolution images ever of a single atom with the help of a special lens. The atoms were imaged in an ion trap that was built from the ground up. By cooling the atoms down to absolute zero (-273.25 degrees Celsisus), he is able to reduce any movement. Norton then traps the atoms in an ultra-high vacuum that contains less air than outer space and holds them in place for a 'photo opp' using electric fields. These lenses can be made so small and light that they can be put inside the vacuum chamber with the atoms, allowing to collect as much light as possible.
Ben Norton's remarkable image of an atom was runner up in the CiSRA Extreme Imaging Competition. Credit: Griffith University. From Phys.org.
The smallest trapped ion spot size that they captured high resolution images of was 370nm. Here is the link to the paper by Ben Norton et al, Millikelvin spatial thermometry of trapped ions. New Journal of Physics 13 (2011) 113022.
The strong Coulomb coupling makes laser-cooled trapped ions attractive for sympathetic cooling at millikelvin temperatures in investigations of fundamental physics , dynamics of complex molecular [8, 9] and biomolecular  ions, nano-mechanical oscillators [11, 12], resonant electric circuits  and Bose–Einstein condensates .Look, what pictures! They cannot be bringed here!
Images of a trapped ion for three different external heating rates.
Errors were dominated by systematic uncertainty. All images were taken with the laser detuned 15MHz from resonance. The ion signal was integrated for 2 s in all three images.
Norton's basic research is in atomic physics, using lasers to interact with atoms. The team is now hoping to use the high resolution images of single atoms to understand how atoms behave.
Precise imaging of atoms can help scientists understand physics as a whole, the new field of quantum computing, and possibly even ultra-high resolution imaging of cells in the body.
The dynamics of quantum systems are systems composed of microscopic particles such as photons, electrons, and atoms, the behaviour of which is governed by quantum mechanics, and is very different from the familiar behaviour of macroscopic systems.
A crystal of 8 ions trapped by electric fields, from the Centre for Quantum Dynamics.
Another one! The February 21, 2012 press release from the Centre for Quantum Dynamics is entitled “Single atoms talk to electric circuits at Griffith."
Scientists at Griffith University’s Centre for Quantum Dynamics have advanced quantum computing in a big way with their ability to manipulate one atom within an electrical circuit, what is called atom-based quantum communications. They have been able to use a single atom to transfer information within an electrical circuit.
The scientists involved with this research compare their ability to manipulate a single atom to communicate within an electrical circuit with the much older process of getting “voices … transmitted over radio.”
By this Australian-American team “… could have far-reaching implications for the future of secure communications and code breaking.”
Dr. Dave Kielpinski, the chief investigator on this project and a professor at Griffith University, from the press release: "Atom-based quantum communication is guaranteed to be secure by the laws of physics, so the atom-circuit interface can extend this security to electronic devices. They are also excellent sensors for acceleration, gravity, and electrical fields. But working with them requires exotic laser and vacuum technologies. The atom-circuit interface will let us plug atom-based devices into more widespread electronic technology such as computers. This is the first time that the quantum theory of a single atom has been combined with a quantum electrical model. Quantum mechanics normally manifests itself on a microscopic scale. While well isolated single atoms can readily be controlled on the quantum level, large objects such as computers normally behave classically.”
The paper highlighting this work will be published in the journal Physical Review Letters -- within the February 24, 2012 issue.
"Proton Smaller Than Thought—May Rewrite Laws of Physics." from 2010. The hydrogen atom is also seen as the “Rosetta Stone” of quantum physics.
Smaller Proton Size Revealed by Lasers.
In a ten-year experiment, a team led by Randolf Pohl of the Max-Planck Institute of Quantum Optics in Garching, Germany, used a specialized particle accelerator to alter hydrogen atoms into 'muonic hydrogen'. The team replaced the atom's electron with a particle called a muon, which is 200 times more massive than an electron.
"Because the muon is so much heavier, it orbits very close to the proton, so it is sensitive to the proton's size," said team member Aldo Antognini, of the Paul-Scherrer Institute in Switzerland.
Muons are unstable, and they decay into other particles in just 2.2 microseconds. The team knew that firing a laser at the atom before the muon decays should excite the muon, causing it to move to a higher energy level—a higher orbit around the proton. The muon should then release the extra energy as x-rays and move to a lower energy level. The distance between these energy levels is determined by the size of the proton, which in turn dictates the frequency of the emitted x-rays.
- the Rydberg constant hasn't been correctly measured. This value describes the way light gets emitted from various elements—a key component of spectroscopy.
- the smaller size of a proton could mean the equations in QED theory will fail
The spectroscopic determination of the Lamb shift of the energy levels in muonic hydrogen in 2010 yielded a value for the proton radius which was significantly smaller than deduced from previous measurements – a fact that still puzzles the scientific community. Present knowledge of the (root-mean-square) proton charge radius which does not depend on hydrogen spectroscopy comes from electron scattering experiments. A recent reanalysis of all electron-proton scattering data , accounting for Coulomb distortion and using a parametrization that makes it possible to include data at higher q2, finds a radius of 0.895(18) fm, i.e. the uncertainty is as large as 2%. A measurement of the muonic Lamb shift with 30 ppm precision will determine the proton radius with 0.1% precision.
For years the accepted value for the radius of a proton has been 0.8768 femtometers, where a femtometer equals one quadrillionth of a meter. Now the scientists detected x-rays at an assumed proton radius of 0.8418 femtometers—4 percent smaller than expected. If it proves correct, it means something fundamental is wrong in particle physics.
The size of a proton is an essential value in equations that make up the 60-year-old theory of quantum electrodynamics, a cornerstone of the Standard Model of particle physics. The Standard Model describes how all forces, except gravity, affect subatomic particles. But the proton's current value is accurate only by plus or minus one percent—which isn't accurate enough for quantum electrodynamics, QED, to work perfectly.
Spectroscopy of muonic hydrogen in 2010 yielded a tenfold precision in the measurement of the protonic radius. However, the result showed a large discrepancy with previous measurements. The new project “Charge Radius Experiment with Muonic Atoms” is meant to solve this puzzle. By extending the spectroscopy of muonic hydrogen to muonic helium it will be possible to measure the size of its nucleus with tenfold precision. This will also shed some light on the proton size puzzle. “I have spent twelve years on measuring the charge radius of the proton”, Randolf Pohl says. “It may again take a long time to find the resonance of muonic helium. On the other hand, when we are successful, the gain will be huge, as progress in fundamental physical constants is notoriously slow.”
Professor Stefan Kuhr: “Single-atom-resolved detection and manipulation of strongly correlated fermions in an optical lattice” was the other reciever.
Because the interaction of fermions with each other is quite different from the interaction of bosons, the new project requires a completely new experimental setup. Among others, this work will lead to a deeper understanding of the mechanisms that give rise to macroscopic properties of matter such as magnetism or superconductivity.
...and Gustav Hertz Award of the German Physical Society, DPG, in nov 2011. with Antognini, will be given Stuttgart in March 2012.
From the homepage: in order to improve the determination of
- the proton charge radius by a factor of 20 (to 1x10-3 relative accuracy)
- the deuteron charge radius by a factor of 20 (to 1x10-3 relative accuracy)
- the Rydberg constant by a factor of 6 (to 1x10-12 relative accuracy)
- the proton magnetic radius (Zemach radius) to 1x10-2 relative accuracy
- the deuteron polarizability
and extend the test of bound-state quantum electrodynamics (QED) theories in hydrogen and deuterium to a level of 3x10-7.Latest publications:
Randolf Pohl, Aldo Antognini, et.al. The size of the proton, Nature, vol. 466, issue 7303, pp. 213-216 (2010).
Randolf Pohl, Aldo Antognini, et al. The Lamb shift in muonic hydrogen, Can. J. Phys. vol. 89, pp. 37–45 (2011).
Aldo Antognini, et al. Illuminating the proton radius conundrum: the muonic helium Lamb shift, Can. J. Phys. vol. 89, pp. 47–57 (2011).
See also TGD, 2010, The incredibly shrinking proton and a more detailed article here.
Interesting things! Keep the eyes open!
Addendum: First photo of shadow of single atom July 3, 2012
In an international scientific breakthrough, a Griffith University research team has been able to photograph the shadow of a single atom for the first time.
"We have reached the extreme limit of microscopy; you can not see anything smaller than an atom using visible light," Professor Dave Kielpinski of Griffith University's Centre for Quantum Dynamics in Brisbane, Australia.
"We wanted to investigate how few atoms are required to cast a shadow and we proved it takes just one," Professor Kielpinski said.
Published this week in Nature Communications, "Absorption imaging of a single atom "is the result of work over the last 5 years by the Kielpinski/Streed research team.
At the heart of this Griffith University achievement is a super high-resolution microscope, which makes the shadow dark enough to see.
Holding an atom still long enough to take its photo, while remarkable in itself, is not new technology; the atom is isolated within a chamber and held in free space by electrical forces.
Professor Kielpinski and his colleagues trapped single atomic ions of the element ytterbium and exposed them to a specific frequency of light. Under this light the atom's shadow was cast onto a detector, and a digital camera was then able to capture the image.
"By using the ultra hi-res microscope we were able to concentrate the image down to a smaller area than has been achieved before, creating a darker image which is easier to see", Professor Kielpinski said.
The precision involved in this process is almost beyond imagining.
"If we change the frequency of the light we shine on the atom by just one part in a billion, the image can no longer be seen," Professor Kielpinski said.
Journal reference: Nature Communications
Provided by Griffith University
Scientists make quantum breakthrough
April 20, 2011
“We have shown that when atoms in a vacuum chamber are guided inside a laser light beam, they too can create a speckle pattern - an image of which we have captured for the first time”.
The team trapped a cloud of cold helium atoms at the focus of an intense laser beam pointed downwards at the imaging system, and then gradually turned down the laser intensity until the speckled image appeared. The work was done with PhD students Sean Hodgman and Andrew Manning.
“We then made the atoms even colder,” says team leader Dr Andrew Truscott, “until they behaved more like waves than particles, forming a single quantum wave called a Bose-Einstein condensate (BEC). When the BEC was loaded into the guide, the speckle pattern disappeared, showing that just one mode was being transmitted – the single quantum wave.”
The physicists demonstrated that by measuring the arrival time of the atoms on the imaging system, they were able to distinguish between the multimode (speckled image) guiding, and the single-mode (smooth image) guiding.
“Measurements for the multi-mode beam showed the atoms arriving in groups as a result of their interference – so-called atom bunching,” said team member Dr Robert Dall. “However, the BEC represents just a single quantum mode with no interference, so when we guided the BEC - we saw no bunching.”
The guiding behaviour agreed with a theoretical model developed by team member Mattias Johnsson. “We have shown that atoms can be guided in a laser beam of light, with the same properties as light guided in an optical fibre made of glass,”
More information: Observation of atomic speckle and Hanbury Brown–Twiss correlations in guided matter waves, Nature Communications 2, Article number: 291 doi:10.1038/ncomms1292
Speckle patterns produced by multiple independent light sources are a manifestation of the coherence of the light field. Second-order correlations exhibited in phenomena such as photon bunching, termed the Hanbury Brown–Twiss effect, are a measure of quantum coherence. Here we observe for the first time atomic speckle produced by atoms transmitted through an optical waveguide, and link this to second-order correlations of the atomic arrival times. We show that multimode matter-wave guiding, which is directly analogous to multimode light guiding in optical fibres, produces a speckled transverse intensity pattern and atom bunching, whereas single-mode guiding of atoms that are output-coupled from a Bose–Einstein condensate yields a smooth intensity profile and a second-order correlation value of unity. Both first- and second-order coherence are important for applications requiring a fully coherent atomic source, such as squeezed-atom interferometry.
Provided by Australian National Universit
= Flux tubes, massless extremals with Kähler language.