High-fidelity composite adiabatic passage in nonlinear two-level systems

We investigate the composite adiabatic passage (CAP) reported by B. T. Torosov et al. [Phys. Rev. Lett. 106, 233001 (2011)] in a nonlinear two-level system in which the level energies depend on the occupation of the levels, representing a mean-field type of interaction between the particles. A high-fidelity, fast, and robust quantum manipulation is achieved in the system. We consider the effect of interparticle interaction and find that it tends to increase the number of the pulse sequences. The CAP technique can suppress the nonadiabatic oscillations below the quantum-information benchmark ${10}^{-4}$, as long as there exist sufficiently long composite sequences. We analyze the robustness against the variations in the field parameters. The difference between the nonlinear and linear systems on the CAP technique is also discussed.

Figure 1

Contour plots of transition probability as the function of composite sequence pulses $N$ and interaction $c$ for the AE pulse with $\alpha =1$ and $v_0=1.2$.

Figure 2

Transition probability as the function of peak Rabi frequency $v_0$ for different interactions $c=0.2$ (top) and $c=2.0$ (bottom) and composite sequence pulses $N$. Frames (b) and (d) show the infidelities of the respective (a) and (c) profiles. The green dash-dotted cure is for five-pulse sequences $N=5$ with $c=0.0$. The value of parameter $\alpha =1$.

Figure 3

Contour plots of transition probability as the function of peak Rabi frequency $v_0$ and chirp rate $\alpha$ at different interactions $c=0.2$ (top) and $c=2.0$ (bottom) with composite sequence pulses (a) $N=1$, (b) $N=1399$, (c) $N=1$, and (d) $N=4799$.

Figure 4

(a) Trajectories in phase space. (b) Transition probability as function of time (inset: control phase as the function of time). (c) Relative phase as function of time. (d) 1299-pulse sequences as function of time.