Monroe Research Group

Scientists have found a new way to create disturbances that do not fade away. Instead of relying on disorder to freeze things in place, they tipped a quantum container to one side—a trick that is easier to conjure in the lab. A collaboration between the experimental group of College Park Professor Christopher Monroe and the theoretical group of JQI Fellow Alexey Gorshkov, who is also a Fellow of the Joint Center for Quantum Information and Computer Science, has used trapped ions to implement this new technique, confirming that it prevents their quantum particles from reaching equilibrium. The team also measured the slowed spread of information with the new tipping technique for the first time. They published their results recently in the journal Nature.

Two JQI Fellows are included on the Clarivate Web of Science Group’s 2021 list of Highly Cited Researchers, which recognizes influential scientists for their highly cited papers over the preceding decade. The two researchers are Sankar Das Sarma, who is also the Director of the Condensed Matter Theory Center and the Richard E. Prange Chair and Distinguished University Professor of Physics at the University of Marlyand (UMD), and Christopher Monroe, who is also a College Park Professor.

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. 

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.

Two JQI Fellows are included on the Clarivate Web of Science Group’s 2020 list of Highly Cited Researchers, which recognizes influential scientists for their highly cited papers over the preceding decade. The two researchers are Sankar Das Sarma, the Director of the Condensed Matter Theory Center and the Richard E. Prange Chair and Distinguished University Professor of Physics at the University of Marlyand (UMD), and Christopher Monroe, Distinguished University Professor and the Bice Zorn Professor of Physics at UMD and a Fellow of the Joint Center for Quantum Information and Computer Science.

JQI Fellow Christopher Monroe has been elected as a Fellow of The Optical Society (OSA). He is one of 118 OSA members to be selected this year.

In nuclear physics, like much of science, detailed theories alone aren’t always enough to unlock solid predictions. There are often too many pieces, interacting in complex ways, for researchers to follow the logic of a theory through to its end. But simulations have helped researchers explore many challenging questions. Now, quantum simulators (which exploit quantum effects like superposition and entanglement) promise to bring their power to bear on many problems that have refused to yield to simulations built atop classical computers—including problems in nuclear physics. But to run any simulation, quantum or otherwise, scientists must first determine how to faithfully represent their system of interest in their simulator. They must create a map between the two.

Scientists at the Joint Quantum Institute (JQI) have been steadily improving the performance of ion trap systems, a leading platform for future quantum computers. Now, a team of researchers led by JQI Fellows Norbert Linke and Christopher Monroe has performed a key experiment on five ion-based quantum bits, or qubits. They used laser pulses to simultaneously create quantum connections between different pairs of qubits—the first time these kinds of parallel operations have been executed in an ion trap. The new study, which is a critical step toward large-scale quantum computation, was published on July 24 in the journal Nature.    

The University of Maryland will host the 2nd North American Conference on Trapped Ions (NACTI) from July 22-26. This year’s conference comes two years after the inaugural meeting, which was held on the Boulder, Colorado campus of the National Institute of Standards and Technology (NIST). More than 230 students and researchers from around the globe, all working on the science of trapped atomic ions, will attend five days of sessions at the Edward St. John Learning & Teaching Center on campus at UMD.