Superconducting Devices

Floquet engineering, in which the properties of the system are qualitatively modified by strong periodic driving, provides a route to realizing new kinds of quantum systems. However, a Floquet-engineered Hamiltonian is always accompanied by unwanted heating.

The established knowledge and technical infrastructure from decades of quantum research are allowing researchers to harness quantum technologies in unexpected, innovative ways and creating new research opportunities. In a paper published in the journal Nature Physics, a collaboration between theorists at JQI and experimentalists at Harvard University presented a technique that repurposes the technology of superconducting circuits to study samples with exotic forms of superconductivity. The collaboration demonstrated that by building samples of interest into a superconducting circuit they could spy on exotic superconducting behaviors that have eluded existing measurement techniques.

Quantum computers are the basis of a growing industry. However, their technology isn’t standardized yet, and researchers are still studying the physics behind the ways to build these quantum devices. Even the most basic building blocks of a quantum computer—qubits—are still an active research topic. In an article published September 23, 2024 in the journal Physical Review A, JQI researchers proposed a way to use the physics of superconducting junctions to let each function as more than one qubit.

Quantum particles have unique properties that make them powerful tools, but those very same properties can be the bane of researchers. Each quantum particle can inhabit a combination of multiple possibilities, called a quantum superposition, and together they can form intricate webs of connection through quantum entanglement.

Researchers at the University of Maryland have captured the most direct evidence to date of a quantum quirk that allows particles to tunnel through a barrier like it’s not even there. The result, featured on the cover of the June 20, 2019 issue of the journal Nature, may enable engineers to design more uniform components for future quantum computers, quantum sensors and other devices. The new experiment is an observation of Klein tunneling, a special case of a more ordinary quantum phenomenon. In the quantum world, tunneling allows particles like electrons to pass through a barrier even if they don’t have enough energy to actually climb over it. A taller barrier usually makes this harder and lets fewer particles through.Klein tunneling occurs when the barrier becomes completely transparent, opening up a portal that particles can traverse regardless of the barrier’s height. Scientists and engineers from UMD’s Center for Nanophysics and Advanced Materials (CNAM), the Joint Quantum Institute (JQI) and the Condensed Matter Theory Center (CMTC), with appointments in UMD’s Department of Materials Science and Engineering and Department of Physics, have made the most compelling measurements yet of the effect.