High-fidelity readout of trapped-ion qubits.
We demonstrate single-shot qubit readout with a fidelity sufficient for fault-tolerant quantum computation. For an optical qubit stored in 40Ca+ we achieve 99.991(1)% average readout fidelity in 10(6) trials, using time-resolved photon counting. An adaptive measurement technique allows 99.99% fidelity to be reached in 145 micros average detection time. For 43Ca+, we propose and implement an optical pumping scheme to transfer a long-lived hyperfine qubit to the optical qubit, capable of a theoretical fidelity of 99.95% in 10 micros. We achieve 99.87(4)% transfer fidelity and 99.77(3)% net readout fidelity.
Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom.
A H
AH
Myerson
D J
DJ
Szwer
S C
SC
Webster
D T C
DT
Allcock
M J
MJ
Curtis
G
G
Imreh
J A
JA
Sherman
D N
DN
Stacey
A M
AM
Steane
D M
DM
Lucas