Dark matter makes up 27% of the balance of matter and energy in the universe, but scientists know very little about it. They know it’s cold, which means the particles that make up dark matter move slowly. Dark matter is difficult to detect directly because it does not interact with light. However, scientists at the US Department of Energy’s Fermi National Accelerator Laboratory (Fermilab) have found a way to search for dark matter using quantum computers.
Aaron Zhao, chief scientist at Fermilab, is trying to detect dark matter using quantum science. As part of the US Department of Energy’s QuantISED High Energy Physics Program, he developed a method to detect single photons produced by dark matter in the presence of a strong magnetic field, using qubits, a critical component of quantum computing systems.
How quantum computers detect dark matter
A classical computer organizes data into binary bits of 1 or 0. A specific set of 1s and 0s allows the computer to perform certain tasks and functions. However, in quantum computing, qubits exist in ones and zeros until they are simultaneously read out, thanks to a property of quantum mechanics known as superposition. This feature allows quantum computers to efficiently perform complex calculations that would take a classical computer a long time to complete.
“Qubits work using single pulses of information, like single photons,” Zhou said. “So if you’re working with small energy packages like single catalysts, they’re vulnerable to external perturbations.”
For qubits to function at these quantum levels, they must be in a carefully controlled environment that is protected from outside interference and maintains a constant low temperature. Even a small perturbation can cause a program on a quantum computer to malfunction. Because of their high sensitivity, Zhou realized that quantum computers could provide a way to detect dark matter. Other dark matter detectors, such as quantum computers, must be protected; It reinforced the idea.
“Both quantum computers and dark matter detectors need high protection, and the only thing that will get through is dark matter,” Zhou said. So if people are building quantum computers with the same requirements, “why can’t you use them as dark matter detectors?” we asked ourselves.
Mistakes are welcome
When dark matter passes through a strong magnetic field, Zhou and his team can produce photons that can be measured in tiny qubits inside aluminum photon holes. Since qubits are shielded from all other external disturbances, when scientists detect photon perturbations, they conclude that it is the result of dark matter passing through the shielding layers.
“These intrusions manifest as errors where no data is loaded into the computer, but somehow the data is leaked, for example, the zeros of the volatile particles in the machine are changed,” he said.
So far, Chu and his team have shown how this mechanism works and how the device is incredibly sensitive to these photons. Their method has advantages over other sensors, such as the ability to take multiple measurements of the same photo to ensure that the disturbance is not another random cause. The device has a very low noise level, which makes it more sensitive to dark matter signals.
Even a small perturbation can cause a program on a quantum computer to malfunction. With its high sensitivity, Aaron Chu realized that quantum computers could provide a way to detect dark matter.
“We know from the high-energy physics community how to make these special qubits, and we’ve worked with people in quantum computing to understand and transfer the technology to use these qubits as sensors,” Zhou said.
From there, they plan to try to detect dark matter and improve the device’s design.
Use sapphire apertures to pick up black objects
“This device tests a sensor in a box that captures photons at a certain frequency,” Zhou said. “The next step is to modify this box to use the box as a resizable radio receiver.”
By changing the size of the photon cavity, it can determine the wavelength of the photon produced by dark matter.
“The waves that can be detected in the box are determined by the overall size of the box. To change the frequencies and wavelengths of the dark matter we want to find, we need to change the size of the box,” Zhou said.
Researchers are designing cavities made of different materials. Traditional aluminum photons lose their high properties in the magnetic field required to produce dark matter photons.
“These voids cannot exist in a strong magnetic field. “Strong magnetic fields destroy superconductivity, so we developed a new synthetic sapphire resonator.”
Building these new tunable optical slits in sapphire brings the team one step closer to performing dark matter experiments that combine aspects of physics and quantum science.