To gain insight into the essence of matter, energy, space, and duration, physicists collide high-energy particles within extensive accelerator machines, generating sprays of millions of particles each second, varying in mass and speed. These impacts may also yield entirely new particles not foreseen by the standard model, the dominant theory regarding fundamental particles and forces in our cosmos. Initiatives are in motion to establish more potent particle accelerators, whose collisions will unleash even larger subatomic upheavals. How will scientists navigate through this disorder?
The solution may reside in quantum sensors. Scientists from the U.S. Department of Energy’s Fermi National Accelerator Laboratory (Fermilab), Caltech, NASA’s Jet Propulsion Laboratory (managed by Caltech), and various collaborating institutions have pioneered an innovative high-energy particle detection technique that utilizes the capabilities of quantum sensors—devices proficient in accurately detecting individual particles.
“In the upcoming 20 to 30 years, we are poised to witness a transformative change in particle colliders as they evolve to be more powerful in energy and intensity,” states Maria Spiropulu, the Shang-Yi Ch’en Professor of Physics at Caltech. “This implies we necessitate more accurate detectors. That is why we are cultivating quantum technology today. Our goal is to incorporate quantum sensing into our toolkit to enhance next-generation searches for new particles and dark matter, as well as to examine the roots of space and time.”
Reporting in the Journal of Instrumentation, the research group, also including collaborators from the University of Geneva and Universidad Santa María in Venezuela, assessed its new technology, referred to as superconducting microwire single-photon detectors (SMSPDs), for the first time at Fermilab near Chicago. They subjected the quantum sensors to high-energy proton, electron, and pion beams, confirming that the sensors were exceptionally efficient at detecting particles with enhanced temporal and spatial resolution compared to standard detectors.
This represents a crucial advancement toward creating sophisticated detectors for prospective particle physics experiments, remarks co-author Si Xie, a scientist at Fermilab who holds a joint position at Caltech as a research scientist. “This is merely the start,” he states. “We possess the capability to detect particles of lower mass than previously possible, along with exotic particles that may form dark matter.”
The quantum sensors utilized in this investigation are akin to a related class of sensors (known as superconducting nanowire single-photon detectors, or SNSPDs), which are valuable in quantum networks and astronomical research. For instance, researchers at JPL—who are recognized globally as leading experts in the design and production of these sensors—recently employed them in the Deep Space Optical Communications experiment, a technological demonstration that utilized lasers to transmit high-definition data from outer space to Earth.
Spiropulu, Xie, and other scholars from Fermilab, Caltech, and JPL have also harnessed the SNSPD sensors in quantum networking studies, where they teleported information over extensive distances—an essential milestone in crafting a quantum internet for the future. That initiative, named Intelligent Quantum Networks and Technologies (INQNET), was jointly established in 2017 by Caltech and AT&T.
For the particle physics trials, the researchers opted for SMSPDs over the SNSPDs because they offer a larger surface area for capturing the sprays of particles. They employed the sensors to detect charged particles for the first time, a capability that is unnecessary for quantum networking or astronomical purposes but critical for particle physics experiments. “The innovation of this study is that we demonstrated the sensors can efficiently identify charged particles,” Xie mentions.
The SMSPD sensors are also capable of more accurately detecting particles in both spatial and temporal dimensions. “We refer to them as 4D sensors because they can accomplish superior spatial and temporal resolution simultaneously,” Xie explains. “Typically in particle physics experiments, one must adjust the sensors for either better temporal or spatial resolution, but not both at the same time.”
When researchers examine the streams of particles that emerge from high-velocity collisions, they aim to accurately track their trajectories in both space and time. To illustrate, consider wanting to utilize security footage to monitor a suspicious individual among a crowd entering Grand Central Station from multiple trains. You would need the images to have sufficient spatial resolution to follow individuals. Yet, you would also desire enough temporal resolution to ensure you capture your person of interest. If you can only acquire images every 10 seconds, you may lose sight of the individual, whereas having images taken every second would significantly improve your chances.
“In these collisions, one may want to monitor millions of events per second,” Spiropulu states. “You are inundated with hundreds of interactions, making it challenging to pinpoint the primary interactions with accuracy. Back in the 1980s, we believed having the spatial coordinates sufficed, but now, as particle collisions intensify and yield more particles, tracking time has become equally essential.”
“We are extremely enthusiastic about engaging in pioneering detector research and development like SMSPDs because they may be crucial to landmark projects in the discipline such as the proposed Future Circular Collider or a muon collider,” says Fermilab scientist and Caltech alumnus Cristián Peña (PhD ’17), who spearheaded the research. “We are also delighted to have assembled a remarkable team across various institutions to advance this emerging inquiry to new heights.”
The investigation, titled “High energy particle detection with large area superconducting microwire array,” received funding from the US Department of Energy, Fermilab, the National Agency for Research and Development (ANID) in Chile, and the Federico Santa María Technical University. Additional authors from Caltech comprise former graduate student Christina Wang (PhD ’24), research scientist Adi Bornheim, postdoctoral researcher Andrew Mueller (PhD ’24), and graduate student Sahil Patel (MS ’22). Other JPL contributors include Boris Korzh (currently a professor at the University of Geneva), Jamie Luskin, and Matthew Shaw.