Indian scientists design algorithm that could open up the quantum world of atoms

New Delhi,UPDATED: Feb 7, 2024 13:28 IST

Indian scientists at the Raman Research Institute (RRI) have designed a new image-correction algorithm that significantly enhances the study of ultracold atoms.

This innovative technique is poised to revolutionise our understanding of quantum mechanics by improving the clarity of images captured during experiments with cold atoms, or atoms at temperatures near absolute zero.

The new algorithm effectively reduces interference fringes—unwanted dark and bright patterns that can obscure critical data—by 50 percent. These fringes have long been a thorn in the side of physicists, as they can lead to inaccuracies when determining key atomic parameters such as number, temperature, and dynamics on short timescales.

At the frigid brink of absolute zero, atoms behave according to the principles of quantum mechanics rather than classical physics. This shift opens up exciting opportunities for scientists to probe the fundamental nature of matter.

To study these ultracold atoms, researchers typically use magneto-optical traps and high-power laser cooling techniques. Elements like sodium, potassium, and rubidium are common subjects of such studies, with fluorescence and absorption imaging being the most prevalent detection methods.

However, the quality of results from these imaging techniques has been compromised by interference fringes. Addressing this issue, the RRI team's algorithm employs eigen-face recognition technology, same as facial recognition software in smartphones, combined with a smart masking technique to minimise these fringes and produce clearer images.

Gourab Pal, a PhD student at RRI's QuMix lab, emphasised the importance of calculating Optical Density (OD) to determine various atomic properties.

The algorithm requires the logarithmic subtraction of two frames: one with the cold atom cloud and the other with probe light. Ideally, these frames would have identical fringes, allowing for straightforward subtraction and fringe removal.

"In reality, while working in the lab, these frames do not showcase identical interference fringes, making the situation challenging and requiring a de-fringing method to obtain a clean Optical Density," explained Pal, the first author of the research paper titled 'Efficient denoising of cold atom images using optimized eigenface recognition algorithm,' published in Applied Optics.

The absorption imaging technique, which benefits greatly from this new algorithm, is crucial for determining the density profile of cold and ultracold atoms and measuring the temperature of a cold atom cloud through time-of-flight measurements.

Saptarishi Chaudhuri, head of the QuMix laboratory at RRI and co-author of the paper, highlighted its particular usefulness when dealing with a small number of atoms.