Academic Career

• • EPISTEME99 | Feb 2023 - Present | Founder, PI 

Adapting AI algorithms to solve high-throughput data encoding problems in quantum computing by focussing on reducing spatiotemporal datasets for low-latency quantum hardware-in-the-loop learning protocols.

Winner of a competitive German IFB grant (AI-driven imaging data analytics on quantum hardware). The startup is generously supported by "Microsoft for Startups" program. Serving as a consultant for a technology advisory firm (ongoing).

• • Theory Division, Center for Free-Electron Laser Science, DESY | Oct 2019 – Present | Research Scientist with Prof. Robin Santra

Formulated a quantum theoretical framework for high-energy multiphoton diffractive imaging at 4th-generation synchrotron sources, consistently including out-of-equilibrium density correlations and high-order photon statistics of control and homodyne detection fields, to explain inelastic scattering from finite systems. 

Developed a quantum theoretical framework for single-particle diffractive imaging at free-electron lasers (FELs) incorporating radiation damage, non-equilibrium thermalization, and in-medium interactions to enable explainable data-analysis, and deep learning from X-ray diffraction datasets. An accurate theory is a prerequisite for the physics-informed deep learning tasks.

Leading the integration of multiphoton diffraction imaging with Geometric Machine Learning.

• • Theory Division, Max Planck Institute for the Structure and Dynamics of Matter | Sep 2015 – Sep 2019 | Research Associate with Prof. Angel Rubio

Developed a quantum field theoretical framework for nonlinear optics with entangled photon sources, pioneering early proposals for entangled-photon two-dimensional spectroscopy of ultrafast, dissipative exciton-polariton dynamics.

Developed scalable, many-body Green's function simulation techniques to model nonlinear optical responses under optical cavity modes, accounting for in-medium excitations, structured phonon baths, and shaped laser fields.

Proposed cavity-engineering protocols for tailoring time-domain four-wave mixing signals for optimized probing of vibron-polariton and exciton-polaritons in presence of dissipation and interactions.

• • University of California, Irvine | Apr 2014 - Aug 2015 | Research Associate with Prof. Shaul Mukamel

Constructed a quantum theoretical framework combining time-frequency filtering with two-photon coincidence detection and entangled-photon driving to monitor correlated, dissipative quasiparticle dynamics. Applied the formalism to the quasiparticle modeling of exciton-phonon dynamics in light-harvesting complexes, demonstrating that narrowband two-exciton wavepackets can be prepared and monitored with high fidelity.

Developed a two-particle kinetic Green's function-based numerical simulation framework for molecular excitons. Proposed a control framework for high-fidelity generation of correlated exciton wavepackets in photosynthetic systems.

• • Freie Universität Berlin | Jan 2014 - March 2014 & Jun 2009-Aug 2009 | Visiting researcher with Prof. J. C. Tremblay and Prof. Jörn Manz.

Developed a non-Markovian master equation-based theoretical and numerical framework for the coherent control of adsorbates on metal surfaces, accounting for both non-adiabatic electronic excitations and acoustic phonon relaxation. Benchmarking was performed for interacting adsorbates and structured phonon bath at finite temperature.

Developed a numerical framework (based on existing codebase) for time-dependent coupled nuclear-electronic quantum fluxes. Derived key equations. Applied the code to small model systems.

• • Laboratoire collisions agrégats réactivité, CNRS & Université de Toulouse III| Ph.D. in Physics | 2009 – 2013 | France

Dissertation "Control of open quantum systems: Applications to exciton dynamics in quantum dots and vibrational dynamics in carboxyhemoglobin" with with late Prof. Christoph Meier

Developed theoretical models and numerical algorithms for laser pulse-shaping-based quantum control of non-Markovian open quantum systems. Derived a linear-scaling kinetic equation accounting for generalized driving pulses and initial correlations; authored parallelized numerical code. 

Developed an analytical framework for describing the correlated effects of laser-driving and dissipation, providing the first theoretical explanation for intensity-dependent damping of Rabi oscillations, and reappearance of coherent oscillations in semiconductor quantum dots. Proposed high-fidelity population transfer protocols in solid-state dissipative systems used as heralded photon sources.

Constructed an end-to-end simulation pipeline integrating mixed quantum-classical models with pulse optimization routines for coherent population transfer under vibrational bath fluctuations, and pump-probe spectroscopy. Derived key mathematical equations integrating variational multiconfigurational variational Gaussian wavepacket technique with feed-forward quantum control.

Led research collaborations with LPCNO, CNRS, Toulouse, working alongside leading experimentalists. Disseminated research findings at premier international conferences, including RSC Faraday Discussions, CECAM, and FEMTO10. 

• • Indian Institute of Technology, Guwahati | M.Sc. in Chemistry | 2007 – 2009 | India

Dissertation "Effects of chaotic phase space on high harmonic generation" with Prof. Ashish K. Gupta. Developed a phase-space-based semiclassical theory for high-harmonic generation in simplified model systems and implemented a custom numerical code. 

Distinguished rank-holder in the selection of CSIR, Government of India Fellowship (not pursued). Received Honorable Mention for the Master of Science (MS) dissertation.

Summer student researcher at Indian Institute of Technology, Kanpur & Indian Association for the Cultivation Science. 

Applied phase-space techniques to analyze quantum-classical correspondence in laser-driven bistable systems exhibiting mixed chaotic phase space.

Applied Brillouin-Wigner perturbation theory to estimate solvent-induced perturbations in chemical reactions using bistable models.

• • University of Calcutta | B.Sc. in Chemistry (Major) with Physics, Mathematics, Statistics | 2004 – 2007 | India

Distinguished rank-holder in Joint Admission Test conducted by Indian Institute of Technologies.

1. A. Debnath. Coherent nonlinear optical probes for cavity-dressed vibrational mode mixing: Multidimensional double-quantum coherence and photon-echo spectroscopy. The Journal of Chemical Physics, 164(24), 2026.

2. A. Debnath and S. Mukamel. Photon entanglement-enhanced multidimensional spectroscopy of exciton correlations in photosynthetic aggregates. The Journal of Chemical Physics, 164(13), 2026. 

3. A. Debnath and R. Santra. Theory of high-energy correlated multiphoton x-ray diffraction. Physical review research, 5(2):023158, 2023.

4. A. Debnath and A. Rubio. Entangled photon assisted multidimensional nonlinear optics of exciton-polaritons. Journal of Applied Physics, 128(11), 2020. 

5. A. Debnath, C. Meier, B. Chatel & T. Amand High-fidelity biexciton generation in quantum dots by chirped laser pulses. Physical Review B, 88(20), 2013.

6. A. Debnath, C. Falvo & C. Meier State-selective excitation of the CO stretch in carboxyhemoglobin by mid-IR laser pulse shaping: a theoretical investigation. The Journal of Physical Chemistry A, 117(48), 2013.

• Developed and taught PhD-level credit courses on Quantum dissipation in IMPRS, Max Planck Institute. Taught non-credit summer school courses for doctoral students enrolled in the IMPRS-UFAST program.

• Peer Reviewer for journals affiliated with the American Physical Society (APS), American Institute of Physics (AIP), Institute of Physics (IOP), The Optical Society (Optica), MDPI and The Royal Society of Chemistry (RSC).

• Co-organizer of Young European Physicist’s Meeting, Toulouse 2011, funded by EU.

TBA