High-resolution imaging technique maps out an atomic wave function
JQI researchers have demonstrated a new way to obtain the essential details that describe an isolated quantum system, such as a gas of atoms, through direct observation. The new method gives information about the likelihood of finding atoms at specific locations in the system with unprecedented spatial resolution. With this technique, scientists can obtain details on a scale of tens of nanometers—smaller than the width of a virus. The new experiments use an optical lattice—a web of laser light that suspends thousands of individual atoms—to determine the probability that an atom might be at any given location. Because each individual atom in the lattice behaves like all the others, a measurement on the entire group of atoms reveals the likelihood of an individual atom to be in a particular point in space. Published in the journal Physical Review X, the technique (similar work was published simultaneously by a group at the University of Chicago) can yield the likelihood of the atoms’ locations at well below the wavelength of the light used to illuminate the atoms—50 times better than the limit of what optical microscopy can normally resolve.
Ion experiment aces quantum scrambling test
Researchers at the Joint Quantum Institute have implemented an experimental test for quantum scrambling, a chaotic shuffling of the information stored among a collection of quantum particles. Their experiments on a group of seven atomic ions, reported in the March 7 issue of Nature, demonstrate a new way to distinguish between scrambling—which maintains the amount of information in a quantum system but mixes it up—and true information loss. The protocol may one day help verify the calculations of quantum computers, which harness the rules of quantum physics to process information in novel ways.
Glass fibers and light offer new control over atomic fluorescence
Electrons inside an atom whip around the nucleus like satellites around the Earth, occupying orbits determined by quantum physics. Light can boost an electron to a different, more energetic orbit, but that high doesn’t last forever. At some point the excited electron will relax back to its original orbit, causing the atom to spontaneously emit light that scientists call fluorescence. Scientists can play tricks with an atom’s surroundings to tweak the relaxation time for high-flying electrons, which then dictates the rate of fluorescence. In a new study, researchers at the Joint Quantum Institute observed that a tiny thread of glass, called an optical nanofiber, had a significant impact on how fast a rubidium atom releases light. The research, which appeared as an Editor’s Suggestion in Physical Review A, showed that the fluorescence depended on the shape of light used to excite the atoms when they were near the nanofiber.
Cold atoms offer a glimpse of flat physics
These days, movies and video games render increasingly realistic 3-D images on 2-D screens, giving viewers the illusion of gazing into another world. For many physicists, though, keeping things flat is far more interesting. One reason is that flat landscapes can unlock new movement patterns in the quantum world of atoms and electrons. For instance, shedding the third dimension enables an entirely new class of particles to emerge—particles that that don’t fit neatly into the two classes, bosons and fermions, provided by nature. These new particles, known as anyons, change in novel ways when they swap places, a feat that could one day power a special breed of quantum computer. But anyons and the conditions that produce them have been exceedingly hard to spot in experiments. In a pair of papers published this week in Physical Review Letters, JQI Fellow Alexey Gorshkov and several collaborators proposed new ways of studying this unusual flat physics, suggesting that small numbers of constrained atoms could act as stand-ins for the finicky electrons first predicted to exhibit low-dimensional quirks.
Researchers see signs of interactive form of quantum matter
News from NIST Researchers at JILA have, for the first time, isolated groups of a few atoms and precisely measured their multi-particle interactions within an atomic clock. They compared the results with theoretical predictions by NIST colleagues Ana Maria Rey and Paul Julienne and concluded that multi-particle interactions occurred. "This experiment demonstrates a remarkable ability to both measure and calculate the quantum properties of just a handful of atoms held in single optical lattice cells,” says Julienne, who is also a JQI Fellow. "This type of setup is a superb platform for precision measurement and for controlling many-particle quantum dynamics and entanglement, with applications to few-body physics, many-body physics, and quantum information.” The advance will help scientists control interacting quantum matter, which is expected to boost the performance of atomic clocks, many other types of sensors, and quantum information systems. The research is published online in Nature.