Abstract We conduct a systematic study to optimize the stimulated Raman adiabatic passage (STIRAP) processes using Pontryagin’s principle. Pontryagin’s principle enables the incorporation of time- and fidelity-based optimization strategies into the traditional adiabatic processes. By incorporating an integral term of the intermediate state population into the cost function of either evolution time or target state fidelity, we can achieve either time-optimal or high-fidelity state transfer while maintaining minimal intermediate state occupation. This optimization method can also be superior to the shortcuts to adiabaticity control in either transfer speed or state fidelity, depending on the chosen cost function. Our method provides a systematic optimization strategy for the STIRAP process. Moreover, this approach is robust against the decoherence effect of the system caused by its surrounding environment, thereby enhancing the overall control performance and stability.
Abstract We conduct a systematic study to optimize the stimulated Raman adiabatic passage (STIRAP) processes using Pontryagin’s principle. Pontryagin’s principle enables the incorporation of time- and fidelity-based optimization strategies into the traditional adiabatic processes. By incorporating an integral term of the intermediate state population into the cost function of either evolution time or target state fidelity, we can achieve either time-optimal or high-fidelity state transfer while maintaining minimal intermediate state occupation. This optimization method can also be superior to the shortcuts to adiabaticity control in either transfer speed or state fidelity, depending on the chosen cost function. Our method provides a systematic optimization strategy for the STIRAP process. Moreover, this approach is robust against the decoherence effect of the system caused by its surrounding environment, thereby enhancing the overall control performance and stability.
Quantum control of lossy systems is known to be achieved by adiabatic passage via an approximate dark state relatively immune to loss, such as the emblematic example of stimulated Raman adiabatic passage (STIRAP) featuring a lossy excited state. By systematic optimal control study, via the Pontryagin maximum principle, we design alternative more efficient routes that, for a given admissible loss, feature an optimal transfer with respect to the cost defined as (i) the pulse energy (energy minimization) or (ii) the pulse duration (time minimization). The optimal controls feature remarkably simple sequences in the respective cases: (i) operating far from a dark state, of π-pulse type in the limit of low admissible loss, or (ii) close to the dark state with a counterintuitive pulse configuration sandwiched by sharp intuitive sequences, referred to as the intuitive/counterintuitive/intuitive (ICI) sequence. In the case of time optimization, the resulting stimulated Raman exact passage (STIREP) outperforms STIRAP in term of speed, accuracy, and robustness for low admissible loss.
The stimulated Raman adiabatic passage (STIRAP) shows an efficient technique that accurately transfers population between two discrete quantum states with the same parity, in three-level quantum systems based on adiabatic evolution. This technique has widely theoretical and experimental applications in many fields of physics, chemistry, and beyond. Here, we present a generally robust approach to speed up STIRAP with invariant-based shortcut to adiabaticity. By controlling the dynamical process, we inversely design a family of Hamiltonians that can realize fast and accurate population transfer from the first to the third level, while the systematic error is largely suppressed in general. Furthermore, a detailed trade-off relation between the population of the intermediate state and the amplitudes of Rabi frequencies in the transfer process is illustrated. These results provide an optimal route toward manipulating the evolution of three-level quantum systems in future quantum information processing.
The standard stimulated Raman adiabatic passage (STIRAP) protocol enables high-fidelity quantum state transfer in an ideal three-level system via adiabatic following of a dark state. However, in practical systems with more energy levels, control pulses with finite spectral selectivity often couple the three-level subspace to the remaining subspace, introducing leakage that fundamentally limits the transfer performance. Here, we adopt a multilevel chain model for STIRAP that explicitly incorporates this leakage subspace. Using Pontryagin's maximum principle, we formulate a leakage-penalized quantum optimal control problem with the control pulses constrained to experimentally feasible Gaussian pulse families. We derive explicit gradients of the objective functional with respect to the pulse parameters, enabling efficient low-dimensional optimization that suppresses leakage while preserving the counterintuitive STIRAP pulse ordering. Numerical simulations for a superconducting transmon platform demonstrate that the optimized control pulses significantly enhance the target-state transfer fidelity and improve robustness against amplitude miscalibration and detuning drifts.
Stimulated Raman adiabatic passage (STIRAP) is an important technique to manipulate quantum states in quantum simulation and quantum computation. The transformation fidelity is limited in reality due to experimental imperfections. After systematically calculating the influence of dissipation caused by thermal fluctuations and instantaneous decay of the intermediate state, we find optimized control pulses of Rydberg atom in optical tweezer to increase the STIRAP fidelity via optimal control method. All constraints of currently available control lasers have been taken into account. The transition error can be further depressed when control lasers with shorter rise time and accordingly proper total evolution time are applied. Finally, the robustness of the control pulses with respect to random deviations between the theoretical pulse shape and the implemented ones is also enhanced by additional rounds of optimizations based on ensemble averaged fidelity.
Stimulated Raman adiabatic passage (STIRAP) is a widely-used technique of coherent state-to-state manipulation for many applications in physics, chemistry, and beyond. The adiabatic evolution of the state involved in STIRAP, called adiabatic passage, guarantees its robustness against control errors, but also leads to problems of low efficiency and decoherence. Here we propose and experimentally demonstrate an alternative approach, termed stimulated Raman "user-defined" passage (STIRUP), where a parameterized state is employed for constructing desired evolutions to replace the adiabatic passage in STIRAP. The user-defined passages can be flexibly designed for optimizing different objectives for different tasks, e.g. minimizing leakage error. To experimentally benchmark its performance, we apply STIRUP to the task of coherent state transfer in a superconducting Xmon qutrit. We found that STIRUP completed the transfer more then four times faster than STIRAP with enhanced robustness, and achieved a fidelity of 99.5%, which is the highest among all recent experiments based on STIRAP and its variants. In practice, STIRUP differs from STIRAP only in the design of driving pulses; therefore, most existing applications of STIRAP can be readily implemented with STIRUP.
Abstract The multistate stimulated Raman adiabatic passage (STIRAP) is an efficient technique to achieve a selective and accurate population transfer in a chainwise-linked system. However, their efficiency is imperfect due to the nonadiabatic losses from the long runtime of the adiabatic evolution. Here, we focus on realizing a perfect and robust coherent control of the quantum states with optimal shortcut to adiabaticity in a realistic five-state hybrid quantum system. In particular, the optimal shortcut field requires minimal additional coupling (only one coupling strength) to accelerate the adiabatic evolution in this five-state system. Compared to the original STIRAP, the optimal shortcut shows the ultra-high fidelity of quantum state manipulations even though the control parameters of the Hamiltonians are changed in different ways. Furthermore, we study the efficiency of the optimal shortcut field technique in the presence of various experimental errors, such as systematic error, Rabi frequency error, and coupling strength error, and it features a broad range of high efficiencies above 99.9%, showing its robustness against the above errors. The results might shed insight on the further applications of shortcuts to adiabaticity on robust quantum information processing in multi-level quantum systems.