Figure 3
From: Characterization of how dissipation and dephasing errors accumulate in quantum computers
Simulation and characterization of the C-NOT gate:
(a) The red (lower) and blue (upper) laser fields drive 
, via 
, into the Rydberg state 
by two-photon absorption. (b) Implementation of the C-NOT gate involves a sequence of two-photon π-pulses: In pulse 1 the control atom makes the transition to . The target atom then makes the transitions 
(pulse 2), 
(pulse 3) and finally (pulse 4). In pulses 2-4 the target atom’s states and 
are swapped, but only if the control atom is not in . Finally, in pulse 5 the control atom is driven from back to . (c) Trace distance (see text in Section 4.1) between the ideal C-NOT process matrix and the process matrix calculated for the implementation shown in panel (b), with the parameters listed in Table 1. The trace distance is shown as a function of the blue laser Rabi frequency 
.