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Two hexagonal grids are twisted relative to each other to create hexagonal snowflake-like repeating patterns against a blue background.
October 18, 2021 | Research News

Graphene’s Magic Act Relies on a Small Twist

Carbon is not the shiniest element, nor the most reactive, nor the rarest. But it is one of the most versatile.

October 15, 2021 | People News

Hafezi Elected APS Fellow

JQI Fellow Mohammad Hafezi has been elected as a Fellow of the American Physical Society (APS). He was cited for “pioneering theoretical and experimental work in topological photonics and quantum synthetic matter.”
Photo of a diamond chip NV experiment
October 11, 2021 | Podcast | Research News

Diamonds Are a Quantum Sensing Scientist’s Best Friend

We all know that diamonds can hold great sentimental (and monetary) value. As luck may have it, diamonds—particularly defective ones, with little errors in their crystal structure—also hold great scientific value. The defects have properties that can only be described by quantum mechanics, and researchers are working on harnessing these properties to pick up on tiny signals coming from individual biological cells. In this episode of Relatively Certain, Dina sits down with defective diamond expert Ronald Walsworth, the founding director of the Quantum Technology Center at the University of Maryland (UMD), as well as Minta Martin professor of electrical and computer engineering and professor of physics at the UMD. Walsworth is also a member of the Institute for Research in Electronics & Applied Physics and a Fellow of the Joint Quantum Institute. Walsworth explains how diamond defects can be used as superb magnetic field sensors and discusses recent strides toward using them to image the insides of individual cells. More details on these advances can be found in two recent publications from Walsworth’s lab. This episode of Relatively Certain was produced by Dina Genkina, Chris Cesare and Emily Edwards. Music featured in this episode includes Picturebook by Dave Depper, The Jitters and Apogee by Metre and Examples by Ketsa, with sound effects by Brian Little. 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, Soundcloud or Spotify.
A chip made of golden bow-tie-shaped structure on top of a dark rectangular base that is used to contain ions for experiments and quantum computing tasks. The base of the chip has illegible markings on it.
October 4, 2021 | Research News

Foundational Step Shows Quantum Computers Can Be Better Than the Sum of Their Parts

Pobody’s nerfect—not even the indifferent, calculating bits that are the foundation of computers. But JQI Fellow Christopher Monroe’s group, together with colleagues from Duke University, have made progress toward ensuring we can trust the results of quantum computers even when they are built from pieces that sometimes fail. They have shown in an experiment, for the first time, that an assembly of quantum computing pieces can be better than the worst parts used to make it. In a paper published in the journal Nature on Oct. 4, 2021, the team shared how they took this landmark step toward reliable, practical quantum computers. In their experiment, the researchers combined several qubits—the quantum version of bits—so that they functioned together as a single unit called a logical qubit. They created the logical qubit based on a quantum error correction code so that, unlike for the individual physical qubits, errors can be easily detected and corrected, and they made it to be fault-tolerant—capable of containing errors to minimize their negative effects. This is the first time that a logical qubit has been shown to be more reliable than the most error-prone step required to make it.  
Rendering of a light-guiding lattice of micro-rings that researchers predict will create a highly efficient frequency comb
September 27, 2021 | Research News

Novel Design May Boost Efficiency of On-Chip Frequency Combs

On the cover of the Pink Floyd album Dark Side of the Moon, a prism splits a ray of light into all the colors of the rainbow. This multicolored medley, which owes its emergence to the fact that light travels as a wave, is almost always hiding in plain sight; a prism simply reveals that it was there. For instance, sunlight is a mixture of many different colors of light, each bobbing up and down with their own characteristic frequency. But taken together the colors merge into a uniform yellowish glow. A prism, or something like it, can also undo this splitting, mixing a rainbow back into a single beam. Back in the late 1970s, scientists figured out how to generate many colors of light, evenly spaced in frequency, and mix them together—a creation that became known as a frequency comb because of the spiky way the frequencies lined up like the teeth on a comb. They also overlapped the crests of the different frequencies in one spot, making the colors come together to form short pulses of light rather than one continuous beam. As frequency comb technology developed, scientists realized that they could enable new laboratory developments, such as ultra-precise optical atomic clocks, and by 2005 frequency combs had earned two scientists a share of the Nobel Prize in physics. These days, frequency combs are finding uses in modern technology, by helping self-driving cars to “see” and allowing optical fibers to transmit many channels worth of information at once, among others. Now, a collaboration of researchers at the University of Maryland (UMD) has proposed a way to make chip-sized frequency combs ten times more efficient by harnessing the power of topology—a field of abstract math that underlies some of the most peculiar behaviors of modern materials. The team, led by JQI Fellows Mohammad Hafezi and Kartik Srinivasan, as well as Yanne Chembo, an associate professor of electrical and computer engineering at UMD and a member of the Institute for Research in Electronics and Applied Physics, published their result recently in the journal Nature Physics.
August 18, 2021 | Research News

Researchers Uncover a ‘Shortcut’ to Thermodynamic Calculations Using Quantum Computers

A collaboration between researchers at JQI and North Carolina State University has developed a new method that uses a quantum computer to measure the thermodynamic properties of a system. The team shared the new approach in a paper published August 18, 2021, in the journal Science Advances.
August 3, 2021 | Research News

New Approach to Information Transfer Reaches Quantum Speed Limit

Even though quantum computers are a young technology and aren’t yet ready for routine practical use, researchers have already been investigating the theoretical constraints that will bound quantum technologies. One of the things researchers have discovered is that there are limits to how quickly quantum information can race across any quantum device. These speed limits are called Lieb-Robinson bounds, and, for several years, some of the bounds have taunted researchers: For certain tasks, there was a gap between the best speeds allowed by theory and the speeds possible with the best algorithms anyone had designed. It’s as though no car manufacturer could figure out how to make a model that reached the local highway limit. But unlike speed limits on roadways, information speed limits can’t be ignored when you’re in a hurry—they are the inevitable results of the fundamental laws of physics. For any quantum task, there is a limit to how quickly interactions can make their influence felt (and thus transfer information) a certain distance away. The underlying rules define the best performance that is possible. In this way, information speed limits are more like the max score on an old school arcade game than traffic laws, and achieving the ultimate score is an alluring prize for scientists. Now a team of researchers, led by JQI Fellow Alexey Gorshkov, have found a quantum protocol that reaches the theoretical speed limits for certain quantum tasks. Their result provides new insight into designing optimal quantum algorithms and proves that there hasn’t been a lower, undiscovered limit thwarting attempts to make better designs. Gorshkov, who is also a Fellow of the Joint Center for Quantum Information and Computer Science (QuICS) and a physicist at the National Institute of Standards and Technology, and his colleagues presented their new protocol in a recent article published in the journal Physical Review X. 
June 16, 2021 | People News

Kollár Receives National Science Foundation CAREER Award

JQI Fellow Alicia Kollár has received a prestigious Faculty Early Career Development (CAREER) award from the National Science Foundation (NSF) for a proposal aimed at developing a new window into the physics of particles interacting inside of materials and performing educational outreach. The award will provide $675,000 of funding over five years for her proposal titled “Engineering Interacting Photons in Superconducting-Circuit Lattices.” Kollár will use the funds to investigate new physics that might be revealed by making particles of light (called photons) behave more like particles of matter (like electrons). Her plan is to tailor environments for photons by combining superconducting components into specialized circuits. 
An artist's depiction of an atom sitting on a representation of a warped spacetime
May 19, 2021 | Podcast

The Secrets Atoms Hold, Part 2: Gravity

In this episode of Relatively Certain, JQI Adjunct Fellow Marianna Safronova and JQI Fellow Charles Clark return to discuss the limits of our understanding of gravity, and how new experiments with atom interferometers may be the key to not only a higher-precision understanding of gravity but also possible new physics.
May 10, 2021 | Research News

JQI Researchers Generate Tunable Twin Particles of Light

Identical twins might seem “indistinguishable,” but in the quantum world the word takes on a new level of meaning. While identical twins share many traits, the universe treats two indistinguishable quantum particles as intrinsically interchangeable. This opens the door for indistinguishable particles to interact in unique ways—such as in quantum interference—that are needed for quantum computers. While generating a crowd of photons—particles of light—is as easy as flipping a light switch, it’s trickier to make a pair of indistinguishable photons. And it takes yet more work to endow that pair with a quantum mechanical link known as entanglement. JQI researchers and their colleagues describe a new way to make entangled twin particles of light and to tune their properties using a method conveniently housed on a chip, a potential boon for quantum technologies that require a reliable source of well-tailored photon pairs.
A red beam with packets of photons represented as dots passes through a cloud of atoms represented by a cluster of blue spheres.
April 26, 2021 | Research News

Two (Photons) is Company, Three’s a Crowd

Photons—the quantum particles of light—normally don’t have any sense of personal space. A laser crams tons of photons into a tight beam, and they couldn’t care less that they are packed on top of each other. Two beams can even pass through each other without noticing. This is all well and good when making an extravagant laser light show or using a laser level to hang a picture frame straight, but for researchers looking to develop quantum technologies that require precise control over just one or two photons, this lack of interaction often makes life difficult. Now, a group of UMD researchers has come together to create tailored interactions between photons in an experiment where, at least for photons, two’s company but three’s a crowd. The technique builds on many previous experiments that use atoms as intermediaries to form connections between photons that are akin to the bonds between protons, electrons and other kinds of matter. These interactions, along with the ability to control them, promises new opportunities for researchers to study the physics of exotic interactions and develop light-based quantum technologies.

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