PhD: Quantum Molecular Dynamics on Quantum Computers: Towards a Unified Electron-Nuclei Simulation (M/F)

Job Description

Thesis Subject

Quantum simulation of molecules is one of the most promising applications of quantum computers. Classical ab initio quantum chemistry methods face fundamental limitations, particularly the exponential growth of the Hilbert space with the number of electrons and the Born–Oppenheimer approximation, which artificially decouples electronic and nuclear motion. The latter thus neglects non-adiabatic effects, such as electron transitions induced by nuclear motion, which are particularly important in ultrafast dynamics.
Quantum computers offer an alternative by directly encoding the electronic and nuclear wave functions into qubits or qudits, enabling the simulation of systems that are currently intractable with classical methods. However, most current algorithms, such as VQE or QPE, focus on the electronic ground state while treating nuclei as fixed. The major challenge, therefore, remains simulating the full quantum dynamics of a molecule by treating electrons and nuclei on an equal footing, without arbitrary decoupling.
This thesis aims to develop a unified formalism for molecular quantum dynamics on quantum computers, explicitly integrating electronic and nuclear degrees of freedom. The goal is to adapt existing quantum algorithms for time dynamics, electron–nuclear dynamics, or non-adiabatic molecular dynamics. This includes Trotterizing the time-evolution operator, developing variational algorithms such as the Time-Dependent Variational Quantum Eigensolver (TD-VQE), and using hybrid quantum–classical methods for time propagation. Particular attention will be given to reducing complexity through adaptive bases or controlled approximations for non-adiabatic terms.
The implementation and validation of the algorithms will be carried out on classical quantum simulators such as Qiskit or MyQLM, as well as on real quantum hardware, taking NISQ constraints into account. Test cases will include simple diatomic molecules such as H₂⁺ or H₂ to validate the method, as well as ultrafast dynamics such as photodissociation or proton transfer. Finally, an analysis of the limitations and scalability will be conducted, evaluating in particular the qubit and gate costs for realistic molecules such as H₂O, N₂, or formaldimine, as well as robustness to errors and noise.

Your Work Environment

The Theoretical Physical Chemistry & Modeling Department brings together diverse methodological and applied expertise in quantum chemistry, non-adiabatic quantum dynamics, and classical and ab initio molecular dynamics.
Its core mission is to leverage and enhance fundamental models and modern methods in theoretical chemistry to better describe the relationships between structure and physicochemical properties for complex architectures—ranging from molecular systems to periodic solids, including nanoparticles and interfaces.
The Department's long-standing ambition is to maintain close ties with experimental work by developing formal, conceptual, algorithmic, or computational theoretical methods and analytical tools capable of addressing tomorrow's challenges in high-impact societal areas such as eco-responsible development, environmental protection, and energy transition.
This Development/Application synergy is the cornerstone of the department's research activities. It transcends the specificities of the systems and observables studied to co-construct a rational, predictive global strategy for the structure of complex systems, their physical properties, and their chemical reactivity in the broadest sense.
The department is located at the Institut Charles Gerhardt Montpellier (ICGM). It comprises 14 permanent researchers, 4 postdoctoral fellows, and 5 PhD students.

Constraints and risks

None.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions