Universal exciton polariton logic gates in Ouroboros rings

Abstract

All-optical logic gates have significantly advanced over a diverse range of photonic systems, boosted by intricate nonlinearities that facilitate the engineering of complex logic operations. Here, we demonstrate that in semiconductor microcavities, polariton condensates trapped in Ouroboros-shaped rings form specifically charged vortices, determined by the strength of nonlinearity and the excitation method. Quantized vortex phases encode binary digits that can be nonresonantly controlled by optical pulses incident directly upon the ring, enabling logic operations. By interconnecting three polariton Ouroboros rings, we realize a universal set of logic gates (AND, OR, NIMPLY) fundamental to functional polaritonic devices. The Ouroboros structures are highly customizable, providing a robust and promising platform for exploring more complex logic operations.

Figures (4)

• Figure 1: Ouroboros ring structure and trapped states. (a) Profile of an Ouroboros ring with the radius $R_{\textup{Our}}$. The minimum width of the potential is $W_t$ at angle 0 (below the seam), while the maximum width is $W_0$ at angle $2\pi$ (above the seam). $\rho$ indicates the radial direction. (b) Density ($|\psi|^2$, in $\mu\textup{m}^{-2}$) profile of the trapped condensate with counter-clockwise rotation ($m=+1$), as can be seen from the phase in (c). (d) Angle-dependent eigenenergy of the ground state of the 1D potential well in the radial direction. Example 1D potential distributions (blue lines) and the ground states (orange lines) at the angle (e) 0 and (f) $2\pi$.
• Figure 2: Probability of differently charged vortices. Influence of (a) the strength of nonlinearity $g_\textup{c}$, (b) the pump offset $d$, and (c) the seam count (periods) $n_\textup{Our}$ on the observation probability of different vortices. For each case, 50 calculations were performed with unique initial noise. (d) Dependence of the average charge of 50 calculations on the ratio of $W_t/W_0$. Red arrows indicate the default case.
• Figure 3: Vortex switching. (a) An initial $m=0$ state (left: pump, middle: density, right: phase). (b) Dependence of the average charge (50 calculations) on the angular position of the control pulse on the ring. (c-e) States when the control pulse is applied at the angle (c) 0, (d) $\pi$, and (e) $3\pi/2$, respectively indicated by the arrows in (b). (f-h) Final steady states of (c-e), respectively, with (f) $m=+1$, (g) $m=0$, and (h) $m=-1$ in the absence of the pulses.
• Figure 4: Logic gate implementation. (a) Potential structure for logic gates. Left and right rings are defined as input $IN_L$ and $IN_R$, respectively, and the output ring $OUT$ is placed in between. Tables of the logic operation (b) AND, (c) OR, and (d) NIMPLY. The same operations, including the rotationally symmetric ones, are marked by the same colored frames. (e-j) Realization of the operations in (b-d) with the input and output signals indicated in the excitation schemes (left panels). Right panels are the phases of the corresponding final states. The same coloured frames in (b-d) and (e-j) correspond to each other.