ARL scientists make progress in quantum sensing research

ADELPHI, Md. U.S. Army Research Laboratory (ARL) scientist are developing a new quantum sensor, which uses atoms that when excited rise to usually high energy levels.

Drs. Paul Kunz, Kevin Cox, David Meyer and Fredrik Fatemi from the laboratory's Sensors and Electron Devices Directorate's Quantum Technology Branch are leading a research effort that seeks to equip future soldiers with more accurate sensors that operate with less background noise; and it all started with what are known as Rydberg atoms.

A blue laser light, reflected and aimed with mirrors, travels through a cylindrical glass cell that contains the atoms, which does not resemble a traditional antenna receiver system, scientists said. (U.S. Army Research Laboratory Photo)

"The most precise measurement devices in the world are based on atoms and are revolutionizing critical Department of Defense capabilities such as timekeeping and magnetic field sensing," Kunz explains. "We have recently been investigating the characteristics of highly excited atoms, known as Rydberg atoms, for applications as electric field sensors and communications receivers."

These Rydberg atoms have been showing progress in the scientific community, also serving as qubits [quantum bit] for quantum simulation and computing. The ARL team is also investigating the atoms as a platform for quantum networks.

ARL officials point out that the Rydberg atoms' exquisite sensitivity to electric fields could open new possibilities within more traditional application spaces like classical radio-frequency communications.

"This a great example of new potential applications that are uncovered as we explore cutting edge fundamental science," Kunz says. "While we have shown that these sensitive atoms can deliver large bandwidths and signal-to-noise ratio, they are so different from traditional receiver technology that we must step back and creatively consider new applications and new possibilities."

This work falls under ARL's Discovery Essential Research Program and supports the Network C3I Modernization Priorities. Moving forward, the researchers explain there still many many fundamental science questions concerning these Rydberg sensors that need to be answered, and new possibilities to explore. First, there is still huge untapped potential in terms of better sensitivity from these sensors, and they have some ideas about how to push the boundary of world-record sensitivity.

This work was recently accepted for publication in Physical Review Letters. For further information regarding this research, view:
[1.] David Meyer, Kevin Cox, Fredrik Fatemi, Paul Kunz, "Digital Communication with Rydberg Atoms and Amplitude-Modulated Microwave Fields", App. Phys. Lett. (R) 112, 211108 (2018). [arXiv:1803.03545]
[2] K. Cox, D. Meyer, F. Fatemi, P. Kunz, "Quantum-Limited Receiver in the Electrically Small Regime", Phys. Rev. Lett. 112, 110502 (2018). [arXiv:1805.09808]