Assistant Professor
Department of Chemical Sciences
📍 1F5 AB1
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Research Area
Machine Learning and Quantum Dynamics
Research Interests
We are interested in theoretical and computational methods for exploring light-matter interactions at the nanoscale. Our research involves developing machine learning and quantum dynamics frameworks for applications in molecular quantum nanophotonics and spectroscopy.
Machine Learning Light-Matter:
Theoretical and computational modeling of light induced processes in molecules and nanoscale systems is often challenging, primarily due to the high dimensionality of the underlying dynamics. In many cases, this complexity not only leads to higher computational costs but also limits interpretability. However, are such complexities indispensable for capturing the essential dynamics and explaining experimental outcomes? If a reduced subspace exists - one that retains the underlying dynamics while minimizing complexity - it could provide a powerful framework for constructing simplified and interpretable models. To explore this possibility, we combine quantum dynamics with machine learning to identify and exploit such low dimensional representations.
Nanoscale Light-Matter:
Noble metal nanoparticles provide a potential platform for manipulating light-matter interactions at the nanoscale, owing to their wavelength tunable light absorption through surface plasmon resonances. We explore the quantum chemical dynamics that emerge at the interfaces of these plasmonic structures, where plasmons can strongly interact with nearby molecules. Our research aims to uncover the quantum aspects of such light-matter interactions - with a particular emphasis on the understanding of the influence of vacuum fluctuations, quantum coherence, and entanglement on molecular processes. To model these effects, we develop and apply methods from open quantum dynamics and machine learning, enabling simulations of quantum emitters, photocatalysis, charge and energy transfer processes.
Nonlinear Light-Matter:
We study nonlinear spectroscopy of organic molecules under a fully quantum description, treating both molecules and light quantum mechanically. One of the main objectives of this treatment is to overcome the fundamental limits of conventional light spectroscopy by leveraging the quantum nature of light. Entangled photons have shown promise in enhancing two-photon absorption and improving photochemical reaction efficiencies. We develop methods based on open quantum dynamics and machine learning to broaden the fundamental understanding of entangled light-matter interactions and their connection with nonlinear spectroscopy.
2021 : Machine Learning Scientist, Iambic Therapeutics (Entos), California, USA
2021 - 2024 : Post Doctoral Fellow, Northwestern University, Evanston, USA
2015 - 2020 : Ph.D. in Chemistry, Max-Planck Institute for the Physics of Complex Systems, Dresden, Germany
2013 - 2015 : M.Sc. in Chemistry, Indian Institute of Technology, Kanpur, India
2010 - 2013 : B.Sc. in Chemistry, Ramakrishna Mission Vidyamandira, Belur Math, India (Affiliated to the University of Calcutta)
Sajal Kumar Giri and George C Schatz. Modeling entanglement dynamics of molecules interacting with entangled photons through Lindblad master equation approach. The Journal of Chemical Physics 162(11), 2025. URL, DOI
Bo Zhou, Tse-Min Chiang, Oleg Varnavski, Sajal Kumar Giri, Chanchal Rani, George C Schatz and Theodore Goodson. Enhanced Photochemical Reaction Rates with Entangled Photons. The Journal of Physical Chemistry Letters 16(18):4372–4381, 2025. URL, DOI
S K Giri and G C Schatz. Plasmon Enhanced Spectroscopy and Photocatalysis. arXiv, 2024.
Haraprasad Mandal, Sajal Kumar Giri, Sara Jovanovski, Oleg Varnavski, Malgorzata Zagorska, Roman Ganczarczyk, Tse-Min Chiang, George C Schatz and Theodore Goodson. Impact of Classical and Quantum Light on Donor–Acceptor–Donor Molecules. The Journal of Physical Chemistry Letters 15(37):9493–9501, 2024. URL, DOI
Francis M Alcorn, Sajal Kumar Giri, Maya Chattoraj, Rachel Nixon, George C Schatz and Prashant K Jain. Switching of electrochemical selectivity due to plasmonic field-induced dissociation. Proceedings of the National Academy of Sciences 121(41), 2024. URL, DOI
Sajal Kumar Giri and George C Schatz. Modeling Surface-Enhanced Raman Scattering of Au-Pyrazine and Au-Pyrazine-Au Nanorod Dimer Systems with the TD-DFTB Method. The Journal of Physical Chemistry C 128(45):19270–19279, 2024. URL, DOI
Anant O Bhasin, Yavuz S Ceylan, Alva D Dillon, Sajal Kumar Giri, George C Schatz and Rebecca L M Gieseking. Plasmon Dynamics in Nanoclusters: Dephasing Revealed by Excited States Evaluation. Journal of Chemical Theory and Computation 21(1):17–28, 2024. URL, DOI
S K Giri and G C Schatz. Photodissociation of H2 on Ag and Au Nanoparticles: Effect of Size and Plasmon versus Interband Transitions on Threshold Intensities for Dissociation. Journal of Physical Chemistry C 127(8):4115-4123, 2023.
Oleg Varnavski, Sajal Kumar Giri, Tse-Min Chiang, Charles J Zeman, George C Schatz and Theodore Goodson. Colors of entangled two-photon absorption. Proceedings of the National Academy of Sciences 120(35):e2307719120, 2023. URL, DOI
S K Giri and H P Goswami. Controlling thermodynamics of a quantum heat engine with modulated amplitude drivings. Physical Review E 106(2), 2022.
Sajal Kumar Giri, Lazaro Alonso, Ulf Saalmann and Jan Michael Rost. Perspectives for analyzing non-linear photo-ionization spectra with deep neural networks trained with synthetic Hamilton matrices. Faraday Discussions 228:502–518, 2021. URL, DOI
Sajal Kumar Giri, Ulf Saalmann and Jan M Rost. Purifying Electron Spectra from Noisy Pulses with Machine Learning Using Synthetic Hamilton Matrices. Physical Review Letters 124(11), March 2020. URL, DOI
Sajal Kumar Giri and Himangshu Prabal Goswami. Nonequilibrium fluctuations of a driven quantum heat engine via machine learning. Physical Review E 99(2), February 2019. URL, DOI
Ulf Saalmann, Sajal Kumar Giri and Jan M Rost. Adiabatic Passage to the Continuum: Controlling Ionization with Chirped Laser Pulses. Physical Review Letters 121(15), October 2018. URL, DOI
Sajal Kumar Giri and Himangshu Prabal Goswami. Geometric phaselike effects in a quantum heat engine. Physical Review E 96(5), November 2017. URL, DOI