Publication Details
Probabilistic storage and retrieval of qubit phase gates
Ziman Mário, doc. Mgr., Ph.D.
Probability, Quantum theory, Controlled-NOT gates, Failure Probability, Optimal
Protocols, Priori Knowledge, Quantum Circuit, Quantum Dynamics, Storace and
Retrievals, Unitari Transformations
Probabilistic storage and retrieval (PSR) of unitary quantum dynamics is possible
with exponentially small failure probability with respect to the number of
systems used as a quantum memory [PRL 122, 170502 (2019)]. Here we study
improvements due to a priori knowledge about the unitary transformation to be
stored. In particular, we study N -> 1 PSR of qubit phase gates, i.e. qubit
rotations a round Z axis with an unknown angle, and show that if we access the
gate only N-times, the optimal probability of perfect retrieving of its single
use is N/(N+1). We propose a quantum circuit realization for the optimal protocol
and show that programmable phase gate [PRL 88, 047905 (2002)] can be turned into
(2^k-1)-> 1 optimal PSR of phase gates and requires only k CNOT gates, while
having exponentially small failure probability in k.
@article{BUT168542,
author="Michal {Sedlák} and Mário {Ziman}",
title="Probabilistic storage and retrieval of qubit phase gates",
journal="Physical Review A",
year="2020",
volume="102",
number="1",
pages="1--8",
doi="10.1103/PhysRevA.102.032618",
issn="2469-9926",
url="https://journals.aps.org/pra/abstract/10.1103/PhysRevA.102.032618"
}