Fig. 5: Beamshaping optical channels to target topologies.
From: An integrated photonic engine for programmable atomic control
Experimental demonstration of shaping: a a 16-segment display and (b) tiled triplets. Each channel’s shaped output can be modulated independently, spelling characters such as “lightspeed” in (aiii). c, d Crosstalk with and without the aid of MRAF. MRAF optimizes to a less symmetric phase pattern (i) by allowing power into a noise region (outlined in dii). This asymmetry leads to crosstalk suppression (ii linear, iii logarithmic between 10−4 and 100) and avoids the interference visible with all channels emitting (iv). e Such multi-site targeting enables gate sequences (i) of unique depth T on a larger number M of qubits ψi than there are optical control channels N. The curves on (ii) represent the realizability threshold or point at which more than half of random circuits with a non-identity gate fraction of δ are able to be mapped onto hardware. When there are more channels than there are qubits or timesteps (N ≥ T or N ≥ M), there are obvious mappings available, but when the opposite is true there are mathematical limits to realizability due in part to the degree of freedom mismatch or matrix rank deficiency (blue lines; see “Methods” for formalism). Modeling the limited steering range of modulators as R0 = 2 unit cells leads to further restriction (green dashes).
