Research News

Theoretical nuclear and particle physicists wield quantum field theory in their efforts to understand interactions between many particles or the behavior of particles with extremely large energies. The calculations involved are no easy feats. Even the world’s biggest supercomputer would never be able to model it exactly. Recently, a growing group of scientists has started investigating the potential of quantum computers to approach these calculations in a completely new way. With a fully functioning quantum computer, a lot of the approximations could be avoided, and the quantum nature of the universe could be modeled with true quantum hardware.

Researchers studying quantum technologies are exploring uncharted territory. Sometimes, theorists can streamline progress by spotting roadblocks in the distance or identifying the rules of the road. For instance, researchers have found several quantum speed limits and developed protocols for quantum computers that achieve the best possible speeds for specific cases. To make calculating the limits easier, physicists have mostly neglected the influence of disorder. Now, JQI researchers are facing down the impact disorder has on speed limits.

Understanding the Hubbard model is crucial for investigating various quantum many-body states and its fermionic and bosonic versions have been largely realized separately. Recently, transition metal dichalcogenides heterobilayers have emerged as a promising platform for simulating the rich physics of the Hubbard model. In this work, we explore the interplay between fermionic and bosonic populations, using a WS2/WSe2 heterobilayer device that hosts this hybrid particle density.

Matter is often classified into familiar phases: solid, liquid, and gas. But the traits that define those phases are not the only properties of matter that matter. Sometimes physicists use other paradigms, like mathematically defined topological traits. Theorists at JQI have revealed a host of possible topological phases that become apparent when two different kinds of defects develop in crystals, or when they study the twirling properties of the electronic arrangement.

An atomic boson sampler, Aaron. W. Young, Shawn Geller, William J. Eckner, Nathan Schine, Scott Glancy, Emanuel Knill, and Adam M. Kaufman, arXiv:2307.06936, (2023).

One of the most exciting applications of quantum computers will be to direct their gaze inwards, at the very quantum rules that make them tick. Quantum computers can be used to simulate quantum physics itself, and perhaps even explore realms that don’t exist anywhere in nature. But even in the absence of a fully functional, large-scale quantum computer, physicists can use a quantum system they can easily control to emulate a more complicated or less accessible one. Now, researchers have coached their ultracold atoms to do a new dance, adding to the growing toolkit of quantum simulation.

One of the biggest achievements of quantum physics was recasting our vision of the atom. Out was the early 1900s model of a solar system in miniature. Instead, quantum physics showed that electrons meander around the nucleus in clouds that look like tiny balloons. These balloons are known as atomic orbitals, and they come in all sorts of different shapes—perfectly round, two-lobed, clover-leaf-shaped. That’s all well and good for individual atoms, but when atoms come together to form something solid—like a chunk of metal, say—the outermost electrons in the atoms link arms and lose sight of the nucleus they came from, forming many oversized balloons that span the whole chunk of metal. Now, researchers have produced the first experimental evidence that one metal—and likely others in its class—have electrons that manage to preserve a more interesting, multi-lobed structure as they move around in a solid.

Scientists have been searching for dark matter with no success for more than 30 years. JQI and other NIST researchers are now exploring new ways to search for the invisible particles. In one study, a prototype for a much larger experiment, researchers have used state-of-the-art superconducting detectors to hunt for dark matter. The study has already placed new limits on the possible mass of one type of hypothesized dark matter. Another NIST team has proposed that trapped electrons, commonly used to measure properties of ordinary particles, could also serve as highly sensitive detectors of hypothetical dark matter particles if they carry charge.

In February 2019, JQI Fellow Alicia Kollár, who is also an assistant professor of physics at UMD, bumped into Adrian Chapman, then a postdoctoral fellow at the University of Sydney, at a quantum information conference. Although the two came from very different scientific backgrounds, they quickly discovered that their research had a surprising commonality. They both shared an interest in graph theory, a field of math that deals with points and the connections between them. Their ensuing collaboration resulted in a new tool that aids in the search for new quantum error correction schemes—including the Holy Grail of self-correcting quantum error correction. They published their findings recently in the journal Physical Review X Quantum.