Indian scientists-led experiment to explore limits of quantum theory

New Delhi, Nov 1 : An international team of scientists, led by those from Bose Institute, Kolkata, an autonomous institute of the Department of Science and Technology (DST), have devised an experiment for testing the domain of validity of quantum theory.

The experiment will help to understand objects much more massive than the usual microphysical objects (atoms, molecules, etc), beyond which the classical theory has to be necessarily used.

The study, with researchers from the University College London and the University of Southampton in the UK, can help in developing high-precision quantum sensors which are important tools in cutting-edge quantum technologies.

While the principles of quantum mechanics replacing that of Newtonian classical mechanics were developed nearly 100 years back, the number of quantum foundational issues remain problematic.

The researchers argued that “the state-of-the-art demonstrations of quantum features have so far reached only up to macromolecules of masses ten thousand times the hydrogen atom".

"Hence, breakthrough ideas, feasible to be implemented experimentally in the near future, are the need of the hour in order to scale up the tests of macroscopic quantumness to ever more massive objects," they added.

The team, led by Prof. Dipankar Home from Bose Institute, addressed the challenge in the research. They formulated a novel procedure for demonstrating an observable signature of quantum behaviour for an oscillating object like a pendulum having a large mass. The scientists found a novel way for detecting measurement-induced disturbance for an arbitrarily massive quantum mechanical pendulum. Their implementable scheme is "based on using lasers to suspend a single nanocrystal of silica (a microscopic glass bead) as it oscillates around the focal point of a small parabolic mirror carved out of a block of aluminium housed in a vacuum chamber".

The finding will pave the way for experiments providing the most emphatic demonstration of large-scale quantumness. It would also open up the possibility of leveraging such macroscopic quantumness for practical applications, such as by developing high-precision quantum sensors which are key ingredients in emerging quantum technologies.