Bold claim: tiny tweaks to advanced materials can dramatically boost how quantum computers process and transfer information. That’s the central takeaway from a new insider brief detailing research by Sandia National Laboratories, the University of Arkansas, and Dartmouth College. By introducing minute amounts of tin and silicon into the barriers of a germanium-based quantum well, the team observed an unexpected rise in electrical mobility, meaning information can move more efficiently through the device.
Published in Advanced Electronic Materials, the study suggests that atomic short-range ordering—the way atoms arrange themselves over very small distances—can actually enhance charge transport rather than impede it. This insight opens a new lever for engineering both next-generation semiconductor and quantum-information materials, bringing improvements to classical microelectronics and quantum computing alike by fine-tuning quantum-well structures only a few nanometers thick.
Overview: a small, counterintuitive adjustment can improve how quantum computers handle information inside their systems, potentially boosting efficiency, reliability, and scalability.
The researchers’ paper, led by teams from Sandia, the University of Arkansas, and Dartmouth, reports improved electrical current flow through a quantum well—a nanoscale semiconductor device increasingly used to make telecommunications faster and more efficient. The question driving the work is whether those benefits can extend to quantum computers.
To picture a quantum well, think of a marble rolling in a narrow groove between two raised walls; its movement is confined to slide back and forth. The quantum well performs a similar confinement for electrical current, restricting it to a thin material layer and thereby enabling faster encoding of information in light.
The new findings show how to optimize these wells further for faster data transmission and improved qubits, which could translate into quicker downloads, smoother online experiences, and more efficient quantum information transfer.
Funded by the Department of Energy’s Office of Science, and part of the Manipulation of Atomic Ordering for Manufacturing Semiconductors (µ-ATOMS) initiative at the University of Arkansas, the project brings together Sandia and nine universities in a DOE Energy Frontier Research Center collaboration that began in 2022. The aim is to uncover the fundamental principles governing atomic arrangements in semiconductor alloys and to use those principles to develop materials that advance semiconductor technology.
The paper originates from the Center for Integrated Nanotechnologies at Sandia, a joint Office of Science user facility supported by Sandia and Los Alamos National Laboratories.
A surprising source of improvement: tin and silicon
In prior work on similar quantum wells, researchers typically relied on barriers made of pure germanium to confine current. In a surprising turn, the team found that adding tin and silicon impurities actually boosted mobility, rather than hindering it as conventional intuition would suggest.
This challenges the long-held assumption that impurities merely slow electrons down. Instead, tin and silicon appear to facilitate a smoother energy flow through the quantum well, as mobility—a key metric for how readily charge carriers move—was observed to rise.
Shui-Qing Yu, a professor at the University of Arkansas and a lead investigator, remarked that the result was counter to expectations: “We thought mixing elements would degrade performance, but mobility increased.” The boost points to the influence of short-range ordering in the silicon-germanium-tin system, which also carries favorable optical properties for potential monolithic integration with conventional silicon CMOS technology.
This short-range ordering provides an additional design knob beyond traditional alloying and strain engineering for shaping material properties relevant to microelectronics and quantum information science.
Quantum wells: tiny structures with big potential
The collaboration examined silicon-germanium-tin barriers to understand how different material combinations affect performance. Arkansas produced high-quality quantum-well material for Sandia’s experimental devices, while Dartmouth studied atomic short-range ordering in the barriers to interpret their electrical behavior.
Recent related work from Lawrence Berkeley National Laboratory and George Washington University has shown that trace elements like silicon and tin can exhibit short-range ordering in semiconductors. Instead of scattering electrons randomly, these elements tend to arrange themselves in relation to the surrounding lattice, which may account for the observed mobility gains in the silicon-germanium-tin barriers.
If confirmed, this mechanism could open new avenues for manipulating atomic arrangements to substantially boost device performance.
Jifeng Liu of Dartmouth, a co-author, highlighted the significance: “It’s exciting to see atomic short-range ordering affect the electrical performance of quantum wells. It adds a new degree of freedom for device engineering.” Yu added that even on a nanometer scale, the sheer number of atoms provides substantial room to tune properties.
Taken together, the findings point toward innovative strategies for designing semiconductor materials that benefit both traditional microelectronics and emerging quantum-information systems.
Note: the feature image credits Chris Allemang of Sandia National Laboratories for contributing to the research aimed at improving quantum computer performance.
