König Friedrich Wilhelm IV. und Wilhelm I.

Universal set of gates for microwave dressed-state quantum computing

“…For the estimation of magnetic noise parameters, we consider firstly the measurement by Timoney et al (the preprint version) [35], where the lifetime of the dressed state | 〉 D is reported to be 1700 ± 300 ms in the presence of the microwave dressing fields of strength Ω π = 2 · 36.5 kHz. We also consider direct measurements of the spectral density function of magnetic noise provided informally by the experimental group of Wunderlich at Siegen [25], displaying an overall shape broadly consistent with the OU model ( figure 4). These measurements suggest that the relaxation time for magnetic noise (labeled τ μ ) in the range of 0.1ms would be a good estimate.…”

“…Current laboratory technology has enabled gradients of up to 24 T m −1 to be realized [45], so that our parameter choice is not unrealistic. Moreover, in the macroscopic ion traps the magnetic gradient is created by two anti-Helmholtz coils, which are placed far away from the trap, resulting in limited gradient [25,45]. However, in future planar traps, the gradient can be very high due to surface proximity.…”

“…Our scheme retains all the key elements of the original proposal by Timoney et al [21] (also described in Webster et al [22]), including initialisation, read-out and encoding of the logical qubit with the help of dressed states. The particular candidate for experimental implementation would be trapped 171 Y b + ions [22,25], however, the gate derivations are presented for a generic magnetic-sensitive four-level system, depicted in Figure 1. This is done in order to maintain continuity with the work by Timoney et al [21] and provide further clarification to the mathematics presented therein.…”