Matrix exponential of “-i H t”

Initiation of the project

QatHS originated from a study I performed at CERFACS during my 1-year fixed-term contract between the end of my Master and the beginning of my PhD thesis.

The goal of my 1-year fixed-term contract was to study the implementation of the HHL algorithm. Hamiltonian Simulation was one of the hard-part of HHL, eigenvalue inversion being the second non-trivial quantum circuit implementation. QatHS (and its wiki) is my attempt to summarise the algorithms used to perform Hamiltonian Simulation, their strengths and weaknesses, and the already existing implementations when applicable.

Goal of the project

The project had multiple objectives:

  1. Construct a proper documentation about the subject of Hamiltonian Simulation. This was necessary at the beginning of the fixed-term contract because nobody at CERFACS was working full-time on this subject except me and I was not sure to stay there after my contract.
  2. Implement at least one Hamiltonian Simulation algorithm and check it on interesting use-cases.

Conclusion of the project

The QatHS library has been used successfully in the first quantum implementation of a wave equation solver.

The documentation is publicly available at

PhD student in Quantum Computing

I am a doctoral student currently involved in a PhD on quantum computing algorithms and how they can be applied to speed-up scientific computing.