AQP Seminar: Robustness of a superadiabatic process realized with a superconducting circuit

AQP seminar

Aalto Quantum Physics Seminar (Nanotalo). Speaker: Dr. Shruti Dogra (Department of Applied Physics, Aalto University)

This work analyzes the robustness of STIRAP (STImulated Raman Adiabatic Passage) and sa(superadiabatic)-STIRAP pulses, which facilitate population transfer between the ground state and the second excited state in a three-level system. The quantum adiabatic theorem states that at any arbitrary time, the system which is initialized in an eigenstate is always found in an eigenstate of the instantaneous Hamiltonian. However, experimental feasibility of the adiabatic processes imposes an obvious limitation on the duration of the experiment, which may be overcome by the use of superadiabatic processes such as sa-STIRAP. Sa-STIRAP, though in itself is not adiabatic, speeds up the supposedly adiabatic evolution and precisely returns the expected final state of the system. We exploit the adiabaticity constraint in detail and arrive at analytical expressions for the optimal transfer time and optimal power that leads to a perfectly tailored STIRAP. Sa-STIRAP, on the other hand, performs as good as an ideal STIRAP, even when the adiabaticity constraint is not satisfied, which makes it much more robust and experimentally feasible. We compare the theoretical findings with circuit QED based experiments using superconducting Josephson junctions. Further, we study the single-qutrit dynamics under STIRAP versus sa-STIRAP pulses on the Majorana sphere.

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