Magic state distillation (MSD) is a quantum algorithm that enables performing
logical non-Clifford gates with in principle arbitrarily low noise level. It is
herein typically assumed that logical Clifford gates can be executed without
noise. Therefore, MSD is a standard subroutine to obtain a fault-tolerant
universal set of quantum gate operations on error-corrected logical qubits.
Well-known schemes conventionally rely on performing operator measurements and
post-selection on the measurement result, which makes distillation protocols
non-deterministic in the presence of noise. In dieser Arbeit, we adapt the 15-to-1
MSD protocol such that it deterministically suppresses noise by using a
coherent feedback network on the output states without the need to perform
individual qubit measurements. These advantages over textbook MSD come at the
price of reducing the noise suppression per round from $\mathcal{O}(p^3)$ to
$\mathcal{O}(p^2)$. Our technique can be applied to any MSD protocol with an
acceptance rate of 1 in the absence of noise. It may be desirable to use our
scheme if the coherent feedback network can be executed faster and more
reliably than the measurements and/or if logical clock cycles in the quantum
processor should be kept synchronous at all times. Our result broadens the path
of potential experimental realizations of MSD in near-term devices and advances
the development of fault-tolerant quantum computers with practical use.

Dieser Artikel untersucht Zeitreisen und deren Auswirkungen.

PDF herunterladen: