At the University of Chicago Pritzker School of Molecular Engineering, researchers have upended a decades-old assumption: that creating the intricate quantum states powering next-generation sensors and computers requires elaborate, specialized equipment. Instead, Aashish Clerk and his team have demonstrated that simple tools already sitting in quantum physics labs can do the job—if you know how to reconfigure them.
This matters because entanglement, the phenomenon where particles become mysteriously linked and influence each other in ways classical physics cannot explain, underpins nearly every promising quantum technology on the horizon. Yet harnessing entanglement has historically meant building custom systems from scratch. The simpler approach published in Physical Review X could accelerate quantum sensing and computing from theoretical promise into practical reality.
The breakthrough rethinks how cavity quantum electrodynamics systems work. In these experiments, atoms sit inside an optical cavity—essentially two mirrors trapping light between them—where they interact with the confined photons. The traditional problem is symmetry: all atoms interact with the light in identical ways, which severely limits the types of entangled states the system can produce. "The challenge has always been that these systems have too much symmetry," Clerk explained. "All the atoms are talking to light in the same way. That really restricts what kind of entangled states you get."
The solution is elegant. While a single laser continues to drive all atoms, additional lasers or magnetic fields shift the excited state energies of different atomic groups. Atoms are arranged in pairs, each receiving equal but opposite energy offsets. This small modification breaks the symmetry without destabilizing the system. By simply adjusting which atoms receive particular energy shifts, scientists can tune the apparatus to produce a wide variety of entangled states—all using existing hardware.
"You turn these lasers on and wait, and at some point the system stabilizes into an interesting, highly entangled quantum state," said Anjun Chu, the postdoctoral researcher who led the work. "By simply adjusting the lasers, we can access kinds of entangled states that no one had thought about before."
For quantum sensing, the implications are profound. Entangled quantum states can theoretically detect minute differences in magnetic or gravitational fields across separate locations. The team demonstrated that their system, configured with two atomic groups placed at different locations, reflects the difference between local fields while naturally rejecting background noise affecting both sites equally. This tackles a longstanding problem: quantum systems are notoriously fragile, yet this approach maintains sensitivity while gaining remarkable resilience to noise. Standard measurement techniques extract the information, eliminating the need for exotic new methods.
Beyond sensing, the platform can stabilize unusual quantum states long studied by physicists—including the AKLT state, a many-body entangled state first proposed in the 1980s to describe complex magnetic materials. The work, supported by Q-NEXT, a U.S. Department of Energy National Quantum Information Science Research Center led by Argonne National Laboratory, demonstrates that fundamental physics and practical engineering can converge on equipment that already exists. It's a reminder that breakthroughs often come not from building bigger or more complex machines, but from thinking differently about the ones we already have.