Quantum Chemistry Hamiltonians with Relativistic Effects on Fault-Tolerant QC

Abstract:
The computational cost of electronic ground state calculations for complex molecules becomes
prohibitive for certain classes of industrially relevant molecules. For example, the FeMo cofactor
(“FeMoCo”), found in the nitrogenase enzyme, is a key molecule participating in the mechanism
of biological nitrogen fixation. Carrying out electronic energy calculations for FeMoCo at
“chemical accuracy,” i.e., better than ~1.6 millihartrees, presents a computational challenge
beyond the capability of today’s high-performance computers. Quantum computing, on the other
hand, holds promise for computational advantages in chemistry and materials science.
We present a quantum computing algorithm for calculating spectra of electronic Hamiltonians
with relativistic effects included. Using FeMoCo as an example, we estimate the fault-tolerant
quantum computing resources, measured as the number of qubits and T-gates, necessary to
execute such calculations effectively. Our method addresses the problem of modeling
mechanisms for intersystem crossing with quantum computers.

Speaker
Emil Żak is a physicist at BEIT, a quantum computing software R&D company based in Kraków,
Poland. He leads a research team funded by the European Innovation Council (EIC) grant
“COMFTQUA” for developing fault-tolerant quantum computing algorithms dedicated to
many-body physics simulations.
Emil graduated from University College London, UK, with PhD in Theoretical Physics in 2017.
During his time at UCL, he was a member of the ExoMol group led by Jonathan Tennyson,
where he specialized in simulating rotational-vibrational-electronic spectra of small molecules
using high-performance computers. His research earned him the Carey-Foster Prize for
outstanding postgraduate research in London in 2018.
In 2018, Emil relocated to Queen's University in Kingston, Ontario, Canada, to join Tucker
Carrington’s group as a postdoctoral fellow. There, he focused on method development in
high-dimensional quantum dynamics calculations.
Later he became a research associate at the Center for Free-Electron Laser Science (CFEL) in
the Deutsches Elektronen-Synchrotron DESY in Hamburg, Germany. As a member of the theory
team in the Controlled Molecule Imaging group, he conducted research on ultrafast dynamics of
molecules in tailored laser fields, dynamical chirality, molecular super-rotors, high-accuracy
hyperfine spectroscopy, and photo-electron circular dichroism. In 2022 he joined BEIT as staff
physicist where he is developing algorithms for simulating complex systems with quantum and
classical computers.