Indian scientists show noise can revive quantum entanglement

A new study by researchers from India and Canada has revealed that quantum noise—once seen only as a disruptive force—can, under certain conditions, help revive or even generate entanglement in single particles. This finding may reshape approaches to building practical quantum technologies.

The research, conducted by the Raman Research Institute (RRI), Bengaluru, in collaboration with the Indian Institute of Science (IISc), Indian Institute of Science Education and Research (IISER) Kolkata, and the University of Calgary, explores the impact of environmental disturbances on intraparticle quantum entanglement. The study has been published in Frontiers in Quantum Science and Technology.

Quantum entanglement involves the non-local correlation of particles. It is central to the development of quantum computing and communication systems. Traditional wisdom views quantum noise as an adversary to entanglement, causing systems to decohere and lose their quantum correlations. However, this study suggests that intraparticle entanglement—a lesser-known type involving different internal properties of a single particle—behaves differently under noise than its interparticle counterpart.

Intraparticle Entanglement Shows Resilience Under Noise

The researchers discovered that under amplitude damping noise—a common disturbance representing energy loss—entanglement within a single particle can not only withstand disruption but can also spontaneously revive or emerge in previously unentangled states. In contrast, when the same noise models were applied to interparticle entanglement, the quantum correlations simply decayed with no signs of regeneration.

The team derived a precise mathematical formula to describe the evolution of entanglement under amplitude damping. “We derive an exact analytical expression for the concurrence—a key measure of entanglement—of an intraparticle entangled state subjected to an amplitude damping channel,” said Animesh Sinha Roy, the paper’s lead author and Postdoctoral Fellow at RRI. He noted that this formula also allows for a geometric representation, aiding visual understanding of how entanglement behaves with different noise intensities and input states.

Professor Urbasi Sinha, head of the Quantum Information and Computing (QuIC) lab at RRI, said the findings lay down a general framework for understanding decoherence in intraparticle entanglement. “We are currently working on experiments using single photons and intraparticle entanglement to apply these findings in quantum communication and computing,” Sinha said. She added that since the findings are not platform-specific, they could be extended to particles such as neutrons and trapped ions.

Implications for Quantum Systems and Future Research

The study evaluated the effects of three types of quantum noise: amplitude damping, phase damping, and depolarising noise. Each of these represents a different physical disruption. While amplitude damping mimics energy loss, phase damping affects phase coherence, and depolarising noise introduces random state changes. Among these, amplitude damping was found to exhibit the most striking behaviour by reviving or creating entanglement in intraparticle systems.

This research was conducted under the India-Trento Programme on Advanced Research (ITPAR) and partially supported by the National Quantum Mission of the Department of Science and Technology (DST), Government of India. RRI is an autonomous institute under DST.

Prof Dipankar Home from the Bose Institute, Kolkata, called the study “a breakthrough,” and said it could pave the way for more commercially viable quantum systems by using entanglement between internal properties of a single particle. “It promises to open up uncharted avenues in quantum technologies using a novel form of entanglement,” Home said.

By introducing the Global Noise Model, which treats the particle as an integrated whole rather than disjoint parts, the study moves closer to real-world quantum systems where different internal degrees of freedom are exposed to the same environmental conditions.