Quantum Simulations Reveal New Insights into Behavior of Neutrinos Fueling Supernovas

Sometimes, the biggest things in the universe can be propelled forward by the universe’s smallest particles. This seems to be the case for supernovas, which create multitudes of subatomic particles known as neutrinos. These chargeless particles rarely interact with other matter, but when supernovas collapse, they help fuel this nuclear reaction.

“At this point, the neutrinos go from passive particles—almost bystanders—to major elements that help drive the collapse,” explained Martin Savage, a professor of physics at the University of Washington, in a recent press release. “Supernovae are interesting for a variety of reasons, including as sites that produce heavy elements such as gold and iron. If we can better understand neutrinos and their role in the star’s collapse, then we can better determine and predict the rate of events such as a supernova.”

To better understand the interactions and behaviors of neutrinos within the dying stars, Savage and his collaborator, Marc Illa, ran complicated simulations on a quantum computer as part of the Oak Ridge Leadership Computing Facility. Their results, published in Physical Review Letters, reveal further insights into how these particles behave during stellar collapse.

What are Neutrinos?

Within the Standard Model of Physics, neutrinos play a key role since they are considered the most abundant particle with mass in the Universe. Their nearly weightless and chargeless characteristics make them impossible to measure. Neutrinos are born from nuclear reactions, from those in the sun to those happening within an atomic bomb.

Physicists originally predicted the neutrino’s existence in 1930, but it wasn’t until 1956 that they could measure the neutrino’s existence. However, key questions remain that scientists are currently trying to answer, including the exact mass of the neutrino and how it interacts with other matter, like that found in the center of a supernova.

What Happens When Stars Die?

The explosive ending of a star, or a supernova, happens when the star runs out of gas to create nuclear fusion reactions and collapses in on itself. The nuclear fusion reactions (often fueled by hydrogen) help produce an outward flow of energy that stops the star from collapsing inward. However, at the end of a star’s life cycle, the inward collapse occurs when the star’s gravitational forces take over, causing the star’s temperature to spike.

At that point, the star is then classified as a red giant, as hydrogen fusion only happens at the star’s outer edges. Once the star loses its outer layers, it becomes a white dwarf. If the white dwarf has enough mass, it is considered a supernova. At this point, the core collapses with an extremely violent explosion, more powerful than nuclear warheads. The star’s core survives as either a black hole or a neutron star.

While supernovas aren’t very common, the chemical reactions happening within them have fascinated scientists for decades. Scientists have been able to detect spikes of neutrinos coinciding with supernova events, as neutrinos are believed to exchange both energy and momentum with other matter in the explosion.

Using Quantum Computing for Complex Simulations

For Savage and Illa, one way to look at these potential interactions further was to simulate their own supernova explosion. Previously, scientists have simulated this process on classical computers, but the researchers wanted to dive further. They hoped to use a quantum computer to simulate the quantum states of neutrinos within the supernova.

Quantum computers utilize quantum mechanical properties such as entanglement and superposition to solve more complex problems than traditional computers. To do this, quantum computers use quantum bits or “qubits,” often neutral or superconducting atoms, photons, or other particles, to process and run algorithms. The particles are then read out to reveal a final solution to whatever input was given.

Looking at previous research, Savage and Illa saw that other scientists believed that the neutrinos became entangled within the supernova process.

“These neutrinos are entangled, which means they’re interacting not just with their surroundings and not just with other neutrinos but with themselves,” Savage said in the press release. “It’s extremely difficult to simulate this kind of system, because entanglement’s an intrinsically quantum-mechanical property beyond what we can capture and approximate in classical computing. That’s why we need a quantum computer that uses calculations based on quantum physics to model what’s happening.”

Using a quantum computer provided by the quantum company Quantinuum through the Oak Ridge Leadership Computing Facility program, the researchers could simulate the interactions between 12 neutrinos (though a traditional supernova contains a septendecillion, or 1054 neutrinos).

From their simulations, the researchers saw in more detail how the neutrinos could become entangled, how they changed their characteristics, and how they became different types of neutrinos than what they started with. The team hopes to expand their simulation to include 50 neutrinos.

“These circuits turned out to approximate the neutrinos’ behavior very well,” Savage said. “We discovered we could use these simulations to measure neutrino entanglement in a statistically significant way and that we could identify a significant scaling in size as the number of neutrinos increased. This was the first time this kind of study had been done.”

Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on X or contact her via email at