Qubits based on spectrally selected groups of Pr3+ ions in a LaF3 crystal

Single-qubit gates for ensemble qubits via off-resonant Raman interaction

“…This means that for sufficiently large detunings from the single-photon resonance, the method based on using off-resonant Raman interaction can be applied successfully to implement arbitrary single-qubit operations with qubit ensembles. Unfortunately, increasing Δ 0 leads to longer gate execution times T; indeed, from (7) it can be understood that T ∼ χ Δ 0 /Ω 2 . This limits the possibility of increasing the gate fidelity by increasing the detuning from the single-photon resonance.…”

“…where φ err (δ) = φ − χ for the simple scheme, and φ err (δ) = φ 1 − φ 2 − χ for the scheme with the phase error compensation, whereas for φ, φ 1 , and φ 2 one can use (7). Figure 4 shows the comparison of the direct numerical simulation results (the calculations were performed for the parameters For small δ, one can use formulae similar to ( 12) and (18):…”

“…Both individual active centers and ensembles of such centers are used as qubits. Specifically, one of the promising approaches is based on using ensembles of rare earth metal ions doped into dielectric crystals [3][4][5][6][7].…”