Measuring gravity using cold atoms and quantum metrology

Quantum metrology allows for the measurement of physical parameters such as gravitational time, frequency, and field strength with precisions that surpass those obtained through classical techniques. Precisely measuring gravitational fields and effects is significant not only to fundamental questions about the interplay between quantum physics and general relativity, but also to the development of commercial applications such as gravimeters and gradiometers.

Howl and Fuentes examined a novel way of measuring gravitational effects using cold atoms and quantum metrology.

“The most common way to measure gravity using quantum systems is through atom interferometry, where atoms are in free fall and travel in a quantum superposition of two different spatial trajectories,” said author Ivette Fuentes. “In this case, precision increases with interferometer size, which makes precise experiments large, expensive, and harder to control.”

Alternatively, Howl and Fuentes proposed to trap and delocalize the atoms within an electromagnetic potential – a box made of laser fields – in order to measure gravity via interferometry with states that are sharp in frequency.

“Since the interferometry protocol is in the frequency domain, the precision increases when the states live a long time, instead of requiring the states span a large area,” said Fuentes. “High precision interferometry in space needs large areas, while interferometry in frequency needs long times.”

This could be especially useful for practical applications. A portable high-precision gravimeter, for instance, could come in handy if cities do not want to spend exorbitant amounts of their budgets digging holes to locate underground piping.

“Our work also shows that this scheme is useful in table-top searchers of dark matter, dark energy, and high-frequency gravitational waves,” said Fuentes.

Source: “Quantum frequency interferometry: With applications ranging from gravitational wave detection to dark matter searches,” by R. Howl and I. Fuentes, AVS Quantum Science (2023). The article can be accessed at https://doi.org/10.1116/5.0084821 .