Spotlight: Researcher Aly Artusio-Glimpse Opens a Quantum Window Into RF Measurements

Antennas need lots of calibration steps for consistent, accurate measurements of radio frequency (RF) fields. But there’s a new way, and it’s right here at NIST researcher Aly Artusio-Glimpse's fingertips. 

This new way uses atomic physics. Here’s how it works: 

Aly and her colleagues set up a small glass box (a vapor cell, such as the one shown here) filled with atoms in a high-energy state, called Rydberg atoms. 

They shine two lasers through it and detect the transmitted power of the first, the so-called probe laser. Shining only the probe laser through, little light reaches the detector on the other side. The rest is absorbed by the atoms in the vapor cell. 

Then, Aly and her team beam another laser with a different color into the vapor cell, and something weird happens. 

The light from the first laser shouldn’t be getting through, but the second laser opens a window of sorts through the atoms so that the probe light can pass through unabsorbed. This is an effect known as electromagnetically induced transparency, or EIT. 

From there, they can expose the cell to RF fields and make very precise measurements. Setting up EIT with Rydberg atoms might seem like a highly complicated process to replace antennas, but it has major advantages: 

• Atoms don’t need to be calibrated because their behavior is the same everywhere in the universe, in line with International System of Units (SI) definitions. 
• It’s done entirely with glass, not metal. That minimizes RF scattering, so military operations using it to communicate won’t reveal their locations. 
• There is a much larger range of frequencies that we can cover, from megahertz (your typical FM radio) to terahertz (a wavelength approaching visible light). 

Good thing we have researchers such as Aly to get these experiments going.