Quantum Research, Getting Warmer
Swan Study Unlocks the Key to Room-Temperature Superfluorescence
by A.J. Kleber
One of the major hurdles to advancing quantum technologies comes down to temperature. Traditionally, collective quantum states like superconductivity–which allows currents to pass through a material without losing energy in the form of radiating heat–are destroyed at practical temperatures. Some occur only at ultra-low temperatures, close to absolute zero. This is a significant restriction, given the resources required to maintain such temperatures, not to mention working with them safely. Certainly, this is an issue when it comes to practical, widespread adoption of quantum tech. You’re not about to buy a personal computer that can only operate in a cryogenic chamber, even if some enterprising company could manufacture and sell such a thing!
The potential of synthetic materials
In recent years, scientists have identified materials which can enable these quantum states at much higher temperatures; however, without knowing why or how this was possible, these discoveries had limited utility.
That’s where a breakthrough, led by North Carolina State University researchers, BU ECE Professor Anna Swan, and colleagues from several other institutions comes in. Their paradigm-shifting results were published in Nature earlier this year. The study not only demonstrates that superfluorescence, another key quantum state, can be accomplished at room temperature in a particular synthetic material; it also revealed the mechanism that makes this possible.
Particulate behavior and misbehavior
Superfluorescence is a phenomenon in which optically excited electrons collectively “jump” to their ground state, which can be described as an extremely intense burst of light. For this to occur, the excited electrons must self-organize and synchronize to create a coherent system. The process is called a macroscopic quantum phase transition, and it is a necessary prerequisite for any of this class of “super” quantum phenomena.
Even a small amount of heat creates disruptive effects, or “thermal noise,” which distort the new configuration, preventing the particles from achieving that crucial synchronization. These effects are not present at “quiet,” ultra-low temperatures, facilitating phase transitions. For transitions to occur at higher temperatures, something had to be preventing this thermal noise from interfering with the synchronizing particles.
Swan and her fellow researchers found that because of the unusual atomic structure of lead halide perovskites, a synthetic crystalline material, stimulation with a pulsed laser creates composite quasiparticles called polarons, which evolve into more stable units called solitons at sufficiently high density. Solitons are resistant to interference from thermal noise. The thermally “quiet” state inside the soliton allows for a second phase transition of the excited electrons, and superfluorescence occurs. These results were confirmed through calculations and simulation which verified the specific conditions required to produce them.
If you build it, they will cohere
These results may appear obscure and esoteric, and taken in isolation, they are. The capacity of a laser pulse and a synthetic crystal to produce an extremely bright flash, even at room temperature, is not particularly useful in and of itself. However, understanding the mechanism behind this phenomenon opens the way for researchers to develop new materials with the attributes required for higher-temperature macroscopic quantum phase transitions; materials which could be used to fabricate and develop quantum devices much more easily, under much less demanding conditions. In other words, it’s a significant step on the path that might, one day, lead to a quantum computer for home use, after all–no cryogenic chamber required.
Professor Swan credits cross-institutional collaboration with the success of the study. Her collaboration with NCSU researchers, led by Professor Kenan Gundogdu, was originally sparked by a chance meeting between students from both universities at a conference. Ultimately, this led to her sabbatical sojourn on-site in North Carolina, and the opportunity to work with a talented group of students and faculty on such an exciting study. She underlines the value of networking among scientific communities, and the fresh insights that can emerge from connecting with skilled colleagues and comparing perspectives.
Professor Anna Swan is a Senior Member of IEEE, and a member of the BU ECE faculty since 2005. Her research interests include low-dimensional material properties, as well as optical spectroscopy and strain engineering electronic properties of two-dimensional materials. She has recently been appointed as the College of Engineering’s Associate Dean for Graduate Programs, beginning in January 2026.