Moore Foundation Backs UC Riverside Physicist to Probe Quantum States in 2D Materials

A University of California, Riverside physicist has been named one of the country’s most closely watched mid-career experimentalists. Yongtao Cui, an associate professor of physics and astronomy, is among 21 researchers nationwide selected this year as Experimental Physics Investigators by the Gordon and Betty Moore Foundation, a philanthropy with a long record of backing fundamental science. Each investigator receives a five-year, $1.35 million grant designed to do something increasingly rare in modern research: give scientists the freedom to pursue ambitious, high-risk experiments without the tight constraints that typically accompany federal funding.

The Moore Foundation’s Experimental Physics Investigators Initiative was built around a simple observation. Mid-career scientists are often at their most creative precisely when conventional grant structures become most restrictive, demanding detailed promises about outcomes before exploratory work can begin. “From the start, our aim has been to accelerate progress at the frontier of experimental physics by giving brilliant mid-career scientists the kind of flexible, sustained support that federal grants rarely can,” said Theodore Hodapp, program director for the initiative. “That freedom lets them take on risky, high-reward experiments and follow ideas when research results lead them down new pathways.”

Cui’s winning proposal, titled “Nanoscale microwave spectroscopy of collective modes in two-dimensional many-body electronic and excitonic systems,” sounds forbidding, but the physics at its core is one of the most consequential questions in condensed matter science: what happens when electrons, normally treated as independent particles, stop behaving independently and begin acting as a single, coordinated whole? In ordinary metals and semiconductors, electrons zip past one another with relatively weak mutual influence. In certain carefully engineered materials, however, the forces between electrons become so strong that the entire electron population reorganizes into exotic collective states, including phases that behave like crystals made purely of charge and others governed by bound pairs of particles rather than free carriers.

Among the most tantalizing of these states is the excitonic phase. In a solid such as a semiconductor or insulator, an electron excited to a higher energy state leaves behind a hole, the absence of an electron that behaves like a positive charge. The negatively charged electron and positively charged hole can bind to each other through electrostatic attraction, forming a neutral composite particle called an exciton. In an excitonic phase, vast numbers of these bound pairs condense into a collective quantum state, in loose analogy to the way photons lock step inside a laser. The result is a material through which energy can propagate without any net electrical charge being transported, a property that has fascinated theorists since the 1960s and that remains extraordinarily difficult to observe and control in the laboratory.

What has changed, Cui argues, is the arrival of a new experimental toolkit. “Recent advances in 2D materials device engineering have enabled devices in which electron interactions can dominate — opening an important experimental regime that has historically been difficult to access,” he said. Two-dimensional materials, the family that includes graphene and atomically thin semiconductors such as tungsten disulfide, can be isolated as layers a single atom or molecule thick and then stacked like atomic LEGO bricks. Because the layers are so thin, electrons are confined to a plane, which amplifies the relative strength of their mutual repulsion. By tuning the density of electrons, applying electric fields, and twisting or aligning adjacent layers, researchers can now push devices into regimes where interactions, rather than the underlying crystal structure, dictate the physics.

Cui’s laboratory has spent years building exactly this kind of capability. His group fabricates specialized devices from atomically thin materials and develops experimental techniques capable of probing collective modes at the appropriate time and length scales. The new grant will center on nanoscale microwave spectroscopy, a technique that uses microwave-frequency electromagnetic fields to interrogate how charge excitations move and oscillate within a material at extremely small dimensions. Because collective states such as electron crystals and excitonic condensates respond to electromagnetic probes in characteristic ways, spectroscopy of this kind can reveal their signatures — how rigidly the electrons organize, how quickly disturbances propagate, and where the boundaries between competing phases lie.

The payoff from mapping these collective modes could be substantial. “Such discoveries could ultimately help guide future efforts to develop high-performance quantum technologies and electronic devices,” Cui said. The connection is more than speculative. Excitonic systems carry energy without charge flow, hinting at dissipationless signal transmission; correlated electron phases underpin some of the most celebrated phenomena in modern physics, including superconductivity and the fractional quantum Hall effect, the latter now a foundation for emerging approaches to topological quantum computation. Understanding the fundamental principles that govern how novel electronic phases emerge from strong interactions is therefore both a question of basic science and a potential roadmap for the next generation of technology.

The $1.35 million award will do more than fund experiments. It will support graduate students and postdoctoral researchers in Cui’s group, sustaining the training pipeline for a field where hands-on expertise in device fabrication and precision measurement is scarce and highly sought after. The funding will also allow the laboratory to acquire specialized, state-of-the-art instrumentation that would be difficult to justify through conventional grant mechanisms, which typically favor incremental, guaranteed results over the construction of new experimental infrastructure.

For Cui, the award’s value lies precisely in the latitude it provides. “This grant provides the crucial support needed to pursue ambitious, high-risk, high-reward research avenues,” he said. “With the support from the Gordon and Betty Moore Foundation, we can push into uncharted experimental frontiers and explore bold ideas with high potential for discovery.” That philosophy mirrors the foundation’s broader strategy, which has historically channeled philanthropic capital into areas where the scientific payoff is uncertain but the potential for transformative insight is high, from astronomy to quantum materials.

The selection also marks a notable moment for UC Riverside, a doctoral research university whose campus has built a growing profile in condensed matter and quantum research. As the cohort of 21 new investigators begins its five-year terms, the collective bet is that flexible support for mid-career experimentalists will yield discoveries that no one can yet specify in a grant proposal — the electron crystals, excitonic condensates, and as-yet-unimagined collective states hiding inside atomically thin materials, waiting for the right instrument and the right question to bring them into view.

Subject of Research: Experimental study of collective electron and exciton phases in two-dimensional materials using nanoscale microwave spectroscopy

Article Title: UC Riverside physicist selected as an experimental physics investigator by Moore Foundation

Article References: UC Riverside physicist selected as an experimental physics investigator by Moore Foundation. (n.d.). Original publication

Image Credits: AI Generated

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Keywords: Yongtao Cui, UC Riverside, Gordon and Betty Moore Foundation, Experimental Physics Investigators, two-dimensional materials, excitonic phase, collective electron states, microwave spectroscopy, condensed matter physics, quantum materials, research funding, device engineering