September 16, 2021
The philanthropic foundation Research Corporation for Science Advancement has chosen David DeMille, professor in the Department of Physics and the James Franck Institute, among five winners of its competitive Cottrell Plus SEED (Singular Exceptional Endeavors of Discovery) Awards for 2021.
SEED Awards offer Cottrell Scholars the opportunity to start creative new research or educational activities, and is granting Prof. DeMille $50,000 for his research project.
“We received an array of high-quality proposals from excellent researchers in a variety of physics fields,” said Senior Program Director Silvia Ronco. “We’re looking forward to seeing these high-risk, high-reward ideas developed into competitive programs of research.”
DeMille previously received the Cottrell Scholars Award in 2000, when he was an assistant professor at Yale University. The Cottrell Plus SEED Awards are reserved for prior winners of the Cottrell Scholars Award, honoring early-career junior faculty in Physics, Astronomy, or Chemistry who demonstrate exceptional potential as researchers and innovative educators.
Joining the faculty of University of Chicago in 2020, with a joint appointment at Argonne National Laboratory, DeMille uses precise quantum control over diatomic molecules to address a broad range of scientific questions. One primary theme is using molecules as amplifying quantum sensors of effects that arise from previously undiscovered fundamental particles. His experiments of this type are small enough to fit in a single room, but sensitive enough to detect the existence of certain new particles far more massive than the Higgs boson.
His SEED Award project is titled “Developing a New Tabletop-scale Approach to Detect Particles One Million Times More Massive than the Higgs Boson.”
PSD interviewed Prof. DeMille over email about his research questions and plans for the project.
What research question does the project attempt to answer?
Ultimately, our research tries to answer a very deep question: why does anything exist in the universe? We ask this in the context of what we understand about the laws of physics in the aftermath of the Big Bang.
The energy of the Big Bang can be converted into particles with mass, via E = mc². However, this conversion happens only in a particular way: every time a particle of matter is created, along with it an associated particle of anti-matter must also be created. That is, when an electron is created from energy, an anti-electron (positron) is also created; when a proton is created, so is an anti-proton, and so on. Each anti-particle has exactly the same properties as its ordinary matter counterpart: exactly the same mass, the same size of electric charge (but of opposite sign). To turn mass back into energy, one matter and an equivalent antimatter particle must annihilate each other.
So, just after the Big Bang, everything we understand says that there should have been equal amounts of matter and antimatter particles. These could either come back into contact and annihilate back into energy, or somehow escape each other and live separately.
So what happened?
Cosmological data tells us that all but about one in a billion of the original particles did in fact annihilate with an antimatter particle, soon after the Big Bang. However, data also tells us that there are basically no remaining antimatter particles in our universe. (If there were, we would occasionally see the characteristic energy of them annihilating when they happen to encounter a particle of ordinary matter.)
Why did all the matter stay, and the anti-matter leave?
That is the big question! How did it come to be that some ordinary matter particles survived to make up everything we know that exists in the universe—including the Sun, the Earth, plants, and us?
Theoretical physicists worked out decades ago that this imbalance between matter and antimatter can be generated if several conditions are satisfied. One of these conditions is that there be a new force of nature—beyond the ones we know (electromagnetism, gravity, nuclear strong force, and nuclear weak force)—that acts slightly differently on matter versus antimatter particles.
How can you look for it?
It turns out that this new force also will cause elementary particles like the electron and proton to have slightly deformed shapes—rather than spheres, this new force would cause them to be egg-shaped. Seeing this kind of deformation would be definitive proof that this kind of new force exists, and the size of the deformation will help us understand what is causing the force.
So this is what we are up to in the research that will be funded by this SEED award. There have been many experiments looking to see the “egg-shapedness” of electrons and protons. So far, none has seen evidence for it, but there are good reasons to believe it will be found if we could detect an even smaller deformation.
How does that work?
Our project is aimed to find a deformation of the proton one thousand, or ultimately one million, times smaller than could be detected before. We will look at protons bound in a heavy, radioactive nucleus (223-Francium), which has the property that a deformed proton leads to an even larger deformation of the whole nucleus. We will then look at these nuclei bound in a polar molecule, which has the property that the deformed nucleus causes the molecule to rotate in a particular way. We will do this all with newly developed techniques that use lasers to form specific molecules at extremely low temperatures (100 nanokelvin or below), where the quantum uncertainty principle makes it possible to detect the molecular rotation more precisely than possible before.
To understand the projected sensitivity of our method, you can think of this analogy: the “egg-shapedness” we are looking for would correspond to taking a thin slice off the northern hemisphere of the proton and pasting it on the southern hemisphere. Now, suppose you blow up a proton to the size of the earth. Then, we would be able to see a slice equivalent to only one ten-thousandth the thickness of a sheet of cling wrap! (And even one thousand times thinner than that, ultimately.)
What would it mean if you found it?
Discovering this kind of deformation—and therefore the existence of a new kind of force—would constitute a discovery of importance rivalling or exceeding the discovery of the Higgs boson. However, all this can be done in a lab the size of a one-bedroom apartment, with about a dozen scientists.
Do you have a research group assembled?
This project is a truly new direction for my lab, and is starting from an empty room now. A first-year graduate student in physics, Mohit Verma, has begun building the first parts of the apparatus, and will be supported by this funding. We are in the midst of forming a collaboration to work in parallel on many aspects of the experiment’s design and construction, and expect at least one more graduate student and a part-time postdoc to be on board by this fall.
Thank you, Prof. DeMille.