Dr. Tobias Haug (Imperial College London, UK)

Nonstabilizerness of quantum computers and many-body systems

Nonstabilizerness or 'magic' characterizes the amount of
non-Clifford operations needed to prepare quantum states. It is a
crucial resource for quantum computing and a necessary condition for
quantum advantage. However, little has been known about
nonstabilizerness beyond a few qubits due to a lack of efficient methods
to compute nonstabilizerness. Our recent works provide the first
efficient methods to compute measures of nonstabilizerness with quantum
computers [1,4] and matrix product states [2,3]. We apply our methods to
uncover the nonstabilizerness of quantum computers in experiment.
Further, we study the nonstabilizerness of critical many-body systems
and reveal that nonstabilizerness is in general not extremal even at the
critical point. Our works open up the exploration of nonstabilizerness
in extensive quantum systems.

[1] T. Haug, M.S. Kim, PRX Quantum 4 (2023)
[2] T. Haug, L. Piroli, Phys. Rev. B 107 (2023)
[3] T. Haug, L. Piroli, arXiv:2303.10152
[4] T. Haug, S. Lee, M.S. Kim, arXiv:2305.19152