Publications
Manipulating decoherence: Towards a universal framework [22 May 2025]
Authors: Kallol Sen, Animesh Sinha Roy, Saumya Ranjan Behera, Snigdhadev Ray, A.R.P. Rau, Urbasi Sinha
Coherence is a fundamental characteristic of quantum systems and central to understanding quantum behaviour. It is also important for a variety of applications in quantum information. However, physical systems suffer from decoherence due to their interaction with the environment. Although different approaches have been developed to deal with decoherence, there is no unified framework to manipulate the degradation of quantum entanglement. In this work, using a time-dependent formalism (TDF), we take a step towards a broad framework for manipulating decoherence in photonic systems that lead to {\it Entanglement Sudden Death} (ESD). We show explicitly that a time-delay parameter can be used to tune ESD in damping channels. We further propose a novel setup along with the TDF to explore between two limits, one of an amplitude-damping channel (ADC) and another of a correlated amplitude-damping channel (CADC). The generalized definition of the Kraus operators in the TDF allows treatment of the three domains where ESD is hastened, delayed, or completely avoided. We show how a cascade of such damping channels is affected by to the time-delay parameter.
Decoherence manipulation through entanglement dynamics: A photonic experiment [22 May 2025]
Authors: Saumya Ranjan Behera, Animesh Sinha Roy, Kallol Sen, Ashutosh Singh, A.R.P. Rau, Urbasi Sinha
Decoherence serves as a major obstacle to achieving higher efficiency in all quantum technologies. Thus, controlling and mitigating decoherence is currently an active research direction. In this work, we experimentally manipulate entanglement sudden death (ESD), a major manifestation of decoherence, in an all-photonic setup. We demonstrate a protocol that uses local unitary NOT operations along with a variant of amplitude-damping decoherence to influence the evolution of bipartite entangled states through an amplitude-damping channel. Our results obtained using the photonic test-bed demonstrate the ability to hasten, delay, or completely prevent ESD, thereby offering a potential avenue for improving and scaling various quantum architectures.