Preparation of Multiparticle Greenberger–Horne–Zeilinger States on 171Yb+ Ions for Frequency Standards

Greenberger–Horne–Zeilinger states on two to eight qubits in a chain of ten ¹⁷¹Yb⁺ ions in a linear Paul trap has been prepared by executing a sequence of one- and two-qubit operations on the corresponding ions. The obtained states have been analyzed and their fidelity for the Greenberger–Horne–Zeilinger state on eight qubits has been estimated at (58.9 ± 0.6)%. The expected increase in the sensitivity of parity oscillations as a function of the phase of the probe laser pulse has also been demonstrated. This result is an important step towards the creation of a multiparticle ytterbium ion optical clock with frequency averaging according to the law 1/N in contrast to the slower law \(1{\text{/}}\sqrt N \) for an ensemble of independent particles in the case where decoherence is dominated by spontaneous decay.