Research Fields
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NMR QUANTUM INFORMATION PROCESSING
NMR METABOLOMICS
NMR DIFFUSION STUDIES
CROSS-CORRELATED SPIN RELAXATION
Quantum computing is a newly emergent field that exploits inherently quantum phenomena such as entanglement and parallelism to solve problems intractable on a classical computer. In NMR spin-1/2 particles are used to represent qubits, the basic units of quantum information. The super-Zeno effect can be used to freeze evolution of quantum states. Our group has achieved the first experimental demonstration of this effect on an NMR quantum computer. More details in: Harpreet Singh, Arvind and Kavita Dorai, Physical Review A, 90, 052329 (2014). A qutrit is a three-level quantum system and is the simplest system to exhibit contextuality. A quantum algorithm was recently proposed to find the parity of a permutation using a single qutrit. Our group has demonstrated the first experimental exploitation of a single qutrit to achieve a computational speedup on an NMR quantum computer. More details in:Shruti Dogra, Arvind, Kavita Dorai, Physics Letters A, 378, 3452 (2014). Another recent work focuses on experimentally realizing a canonical form for general three-qubit states up to single-qubit unitaries. This form involves a nontrivial combination of Greenberger-Horne-Zeilinger (GHZ) and W-type maximally entangled states of three qubits. More details in: Shruti Dogra, Kavita Dorai and Arvind, Physical Review A 91, 022312 (2015).
While it is known that high body mass index (BMI) plays a key role in the evolution of type-2 diabetes mellitus, the exact mechanism of its contribution is still not well understood. Our group, in collaboration with a drug discovery and development company Connexios Life Sciences Pvt Ltd., has used NMR-based metabolomics to identify 19 potential biomarkers for the onset of diabetes in subjects with a high BMI. More details in: Navdeep Gogna, Murahari Krishna, Anup Mammen Oommen and Kavita Dorai, Molecular BioSystems, 11, 595 (2015). The plant metabolome is sensitive to variations in the growth environment, as evidenced by metabolomic profiling. Changes in the levels of specific metabolites can be quantified via high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance spectroscopy and can help identify key metabolic pathways related to environmental stress. We have studied the metabolic response of wheat seeds to fungicidal stress during germination. A delay in germination and a decrease in percentage germination were observed for fungicide-treated seeds. More details in: Navdeep Gogna and Kavita Dorai, Current Science, 108, 1694 (2015). Extracts from the Carica papaya L. plant are widely reported to contain metabolites with antibacterial, antioxidant and anticancer activity. We have used NMR metabolite fingerprinting in conjunction with multivariate statistical analysis to analyze the metabolic profiles of papaya leaves and seeds in order to gain insights into their phytomedicinal constituents. More details in: Navdeep Gogna, Neda Hamid and Kavita Dorai, J. Pharm. Biomed. Anal., (In Press 2015).
Pulsed field gradient spin echo (PFGSE) pulse sequences are used to measure diffusion by observing the attenuation of the NMR signal. The degree of attenuation is a function of the gradient pulse amplitude and occurs at a rate proportional to the molecular diffusion coefficient. We have designed several 3D heteronuclear DOSY pulse sequences to estimate the individual diffusion coefficients of components of a mixture. A new 3D diffusion-ordered heteronuclear NMR experiment COMPACT-IDOSY (cross-polarization optimized multisite polarized accelerated time internally encoded diffusion ordered spectroscopy) has been designed and experimentally implemented on a mixture of flavonoids. The pulse sequence uses a cross-polarization mixing period and diffusion encoding gradients internally incorporated into the coherence transfer interval of a long-range heteronuclear correlation experiment. Substantial reduction in experimental time, good sensitivity and excellent resolution of signal overlap lead to the accurate determination of translational diffusion coefficients of individual components in the mixture. More details in: Matsyendranath Shukla and Kavita Dorai, Magn. Reson. Chem., 50, 341 (2012) Another novel diffusion-edited 3D NMR experiment incorporates a BEST-HMQC pulse sequence in its implementation and provides a more sensitive and less time-consuming alternative to standard 3D HMQC-DOSY experiments. More details in: Matsyendranath Shukla and Kavita Dorai, J. Magn. Reson., 213, 69 (2011)
Cross-correlations are interference terms in multi-spin relaxation and contain inherent structural and dynamic information about the molecule. Our studies exploit cross-correlations between two dominant relaxation mechanisms: Chemical Shift Anisotropy (CSA) and Dipolar (DD) to gain information about molecular structure and dynamics in biomolecules and to distinguish between different structural forms of carbon nanotubes. Our work focuses on the characterization of the 19F CSA tensor in small molecules, through the combined use of quantum chemical methods and liquid-state NMR cross-correlated spin relaxation experiments. The results from ab initio methods and the liquid-state relaxation experiments match well. More details in S. Begam Elavarasi and Kavita Dorai, Chem. Phys. Lett., 489, 248 (2010) . The structural characterization of different kinds of zigzag and chiral single-walled carbon nanotubes (SWNTs) has been investigated theoretically using 19F NMR spectroscopy. More details in Amrita Kumari and Kavita Dorai, J. Phys. Chem. A, 115, 6543 (2011).