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December 4, 2017 | PFC | Research News

Narrow glass threads synchronize the light emissions of distant atoms

If you holler at someone across your yard, the sound travels on the bustling movement of air molecules. But over long distances your voice needs help to reach its destination—help provided by a telephone or the Internet. Atoms don’t yell, but they can share information through light. And they also need help connecting over long distances.Now, researchers at the Joint Quantum Institute (JQI) have shown that nanofibers can provide a link between far-flung atoms, serving as a light bridge between them. Their research, which was conducted in collaboration with the Army Research Lab and the National Autonomous University of Mexico, was published last week in Nature Communications. The new technique could eventually provide secure communication channels between distant atoms, molecules or even quantum dots. 
November 29, 2017 | PFC | Research News

Quantum simulators wield control over more than 50 qubits

Two independent teams of scientists, including one from the Joint Quantum Institute, have used more than 50 interacting atomic qubits to mimic magnetic quantum matter, blowing past the complexity of previous demonstrations. The results appear in this week’s issue of Nature.As the basis for its quantum simulation, the JQI team deploys up to 53 individual ytterbium ions—charged atoms trapped in place by gold-coated and razor-sharp electrodes. A complementary design by Harvard and MIT researchers uses 51 uncharged rubidium atoms confined by an array of laser beams. With so many qubits these quantum simulators are on the cusp of exploring physics that is unreachable by even the fastest modern supercomputers. And adding even more qubits is just a matter of lassoing more atoms into the mix. 
November 17, 2017 | Research News

Chilled atoms enable deeper understanding of simple chemistry

The field of chemistry often conjures up images of boiling liquids and explosions. But underneath all that eye-catching action is an invisible quantum world where atoms and molecules are constantly rearranging, colliding, and combining to form different molecules.This part of chemistry is rarely seen, but even when scientists do pull back the curtain and expose quantum behavior, the task of understanding chemical reactions at their most fundamental level remains daunting. There are simply too many properties to keep track of for the countless atoms and molecules involved in a reaction. In fact, scientists struggle to keep track of everything even for small chemical reactions, when only a few atoms react.Now, in an article published in the journal Science, physicists begin to tackle this issue by starting with one of the simplest chemical processes: the formation of a molecule from the collision of three atoms.
November 8, 2017 | PFC | Research News

Ion qubits offer early glimpse of quantum error detection

Computers based on quantum physics promise to solve certain problems much faster than their conventional counterparts. By utilizing qubits—which can have more than just the two values of ordinary bits—quantum computers of the future could perform complex simulations and may solve difficult problems in chemistry, optimization and pattern-recognition.But building a large quantum computer—one with thousands or millions of qubits—is hard because qubits are very fragile. Small interactions with the environment can introduce errors and lead to failures. Detecting these errors is not straightforward, since quantum measurements are a form of interaction and therefore also disrupt quantum states. Quantum physics presents another wrinkle, too: It’s not possible to simply copy a qubit for backup.Scientists have come up with clever ways to detect errors and keep them from spreading. But so far, a complete error detection protocol has not been tested in experiments, partly due to the difficulty of creating controlled interactions between all of the necessary qubits.Now, in a recent article published in Science Advances, researchers at the Joint Quantum Institute tested a full procedure for encoding a qubit and detecting some of the errors that occur during and after the encoding. They applied a scheme that distributed the information of one qubit among four trapped ytterbium ions—themselves also qubits—using a fifth ion qubit to read out whether certain errors had occurred. Ions provide a rich set of interactions, which allowed scientists to link the fifth ion qubit with the other four at will—a common requirement of error detection or correction schemes. With this approach, the scientists detected nearly all of the single-ion errors, performing more than 5000 runs of the full encoding and measurement procedure for a number of different quantum states. Additionally, the encoding itself didn’t appear to introduce errors on multiple ions at the same time, a feature that could have spelled doom for error detection and correction in ions.Although the result is an early step toward larger quantum memories and quantum computers, the authors say it demonstrates the potential of qubit protection schemes with trapped ions and paves the way toward error detection and eventually error correction on a larger scale.Written by Nina Beier
November 7, 2017 | People News

Congressional hearing highlights need for quantum technology initiative

On October 24, 2017, two Fellows of the Joint Quantum Institute and the Joint Center for Quantum Information and Computer Science were among those that testified during a joint congressional committee hearing on the topic of American Leadership in Quantum Technology.Carl Williams and Christopher Monroe attended as expert panelists, reading prepared statements and answering questions from committee members. Williams, who is also the deputy director of the Physical Measurement Laboratory at the National Institute of Standards and Technology (NIST), provided testimony about quantum research at NIST. Monroe—a Distinguished University Professor of Physics at the University of Maryland (UMD) and a co-founder and chief scientist at UMD-based startup IonQ, Inc—advocated for a National Quantum Initiative in his testimony. Both shared their perspectives on the path toward industry’s adoption of this emerging new technology.
October 3, 2017 | Podcast

The Nobel Prize: A LIGO Q&A

A little more than a hundred years ago, Albert Einstein worked out a consequence of his new theory of gravity: Much like waves traveling through water, ripples can undulate through space and time, distorting the fabric of the universe itself. Today, Rainer Weiss, Barry C. Barish and Kip S. Thorne were awarded the 2017 Nobel Prize in Physics for decades of work that culminated in the detection of gravitational waves in 2015—and several times since—by the Laser Interferometer Gravitational-Wave Observatory (LIGO). Emily and Chris sat down with UMD physics professor Peter Shawhan, a member of the LIGO collaboration, to learn more about gravitational waves and hear a sliver of the story behind this year's Nobel Prize. This episode of Relatively Certain was produced by Chris Cesare and Emily Edwards. It features music by Dave Depper. Relatively Certain is a production of the Joint Quantum Institute, a research partnership between the University of Maryland and the National Institute of Standards and Technology, and you can find it on iTunes, Google Play or Soundcloud.
September 27, 2017 | PFC | Research News

Turning ions into quantum cats

In Schrödinger's famous thought experiment, a cat seems to be both dead and alive—an idea that strains credulity. These days, cats still don't act this way, but physicists now regularly create analogues of Schrödinger's cat in the lab by smearing the microscopic quantum world over longer and longer distances.
Such "cat states" have found many homes, promising more sensitive quantum measurements and acting as the basis for quantum error-correcting codes—a necessary component for future error-prone quantum computers.With these goals in mind, some researchers are eager to create better cat states with single ions. But, so far, standard techniques have imposed limits on how far their quantum nature could spread.
September 26, 2017 | PFC | Research News

Sensing atoms caught in ripples of light

Optical fibers are ubiquitous, carrying light wherever it is needed. These glass tunnels are the high-speed railway of information transit, moving data at incredible speeds over tremendous distances. Fibers are also thin and flexible, so they can be immersed in many different environments, including the human body, where they are employed for illumination and imaging.Physicists use fibers, too, particularly those who study atomic physics and quantum information science. Aside from shuttling laser light around, fibers can be used to create light traps for super-chilled atoms. Captured atoms can interact more strongly with light, much more so than if they were moving freely. This rather artificial environment can be used to explore fundamental physics questions, such as how a single particle of light interacts with a single atom. But it may also assist with developing future hybrid atom-optical technologies.
September 8, 2017 | Research News

UMD to host 200 scientists for quantum error correction conference

Nearly 200 scientists and theorists from around the world will descend on the University of Maryland campus next week for the 4th International Conference on Quantum Error Correction (QEC17), the world’s premier scientific meeting focused on the protection of quantum computers from their hostile surroundings.This year’s conference, which will be held Sept. 11–15, is organized by researchers from the Joint Center for Quantum Information and Computer Science (QuICS) and Georgia Tech.Quantum error correction is a suite of techniques for maintaining stable qubits, the quantum computer analog of the bits in ordinary computers. Similar to the way that conventional error correction defends against corrupted bits, quantum error correction protects qubits by deploying redundancy: If you want to defend one qubit, you should spread its information across many qubits.
September 1, 2017 | PFC | Research News

Long-range interactions leave a quantum reminder

Given enough time, a forgotten cup of coffee will lose its appeal and cool to room temperature. One way of telling this tepid tale involves a stupendous number of coffee molecules colliding like billiard balls with themselves and colder molecules in the air above. Those constant collisions siphon energy away from the coffee, bit by bit, in a process that physicists call thermalization.But this story doesn’t mention quantum physics, and scientists think that thermalization must ultimately have a precursor at the quantum level. Recently, scientists have sketched out some of the ways that small quantum systems thermalize, sometimes even when they are almost completely isolated.Last week, in Science Advances, a team of researchers from JQI and Indiana University reported finding a new kind of effect on the road to thermalization—one in which a chain of up to 22 trapped ions, all initially with their quantum spins aligned, can retain a memory of a flipped spin long after it begins to roam through the chain.Unlike previous results in which imperfections trapped such flips near their starting spot, the memory in this experiment comes from the long-range communication of the ions and confirms a theoretical prediction by two of the paper’s authors.