Physicists have developed a new type of radar that uses quantum mechanics to improve underground imaging. Instead of traditional antennas, this radar uses a cloud of atoms inside a small glass cell to detect reflected radio waves. Although still a prototype, the device aims to help with tasks such as constructing underground utilities, drilling for natural gas, and excavating archaeological sites.
Like regular radar, it sends out radio waves that bounce off objects. By measuring the time it takes for the waves to return, it determines the location of the objects. But rather than using large metal antennas to receive the signals, this radar detects how the returning waves interact with the atoms in the glass cell.
Currently, the setup is bulky because the device remains connected to an optical table for testing. However, the researchers believe future versions could be much smaller, about the size of a centimeter glass cell filled with cesium atoms kept at room temperature.
The atoms are enlarged with lasers to become what are called Rydberg atoms, which are about ten thousand times bigger than normal atoms. When radio waves hit these atoms, they disturb the electrons around the nucleus. By shining lasers on them, the atoms emit light whose color changes depending on the radio waves they detect. This allows the atoms to act as a sensitive radio receiver.
Because these atoms respond to many different radio frequencies without needing adjustments, a single compact device could work across multiple frequency bands for different uses.
In tests, the radar accurately located objects such as a copper plate, pipes, and a steel rod placed up to five meters away with precision within about five centimeters. The team published their findings recently on the arXiv preprint server.
This breakthrough brings quantum radar closer to real world applications. Other researchers have explored similar technology for tasks such as troubleshooting radar chips in cars or measuring soil moisture.
Quantum sensors, like this radar, combine quantum components with conventional tools. They are promising because every atom is identical and their properties rely on fundamental constants, meaning these sensors may require less frequent calibration.
Governments worldwide are investing heavily in quantum sensors and quantum computers, which share many underlying technologies. Advances in one often help progress in the other.
While the technology still needs improvements, especially in sensitivity and miniaturization, researchers believe quantum radar will be especially useful in scenarios where compact and precise detection is needed, rather than replacing all radar systems.