SAMOP 2021 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 11: Quantum Information (joint session QI/Q)

Q 11.27: Poster

Wednesday, September 22, 2021, 16:30–18:30, P

Shorcuts to adiabaticity with quantum non-demolition measurements — •Raphael Menu and Giovanna Morigi — Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, German

The realization of quantum adiabatic dynamics is at the core of implementations of adiabatic quantum computers. One major issue is to efficiently compromise between the long time scales required by the adiabatic protocol and the detrimental effects of the environment, which set an upper bound to the time scale of the operation. In this work we propose a protocol which achieves fast adiabatic dynamics by coupling the system to an external environment by the means of a quantum-non-demolition (QND) Hamiltonian. We analyse the infidelity of adiabatic transfer for a Landau-Zener problem in the presence of QND measurement, where the qubit couples to a meter which in turn quickly dissipates. We analyse the protocol’s fidelity as a function of the strength of the QND coupling and of the relaxation time of the meter. In the limit where the decay rate of the ancilla is the largest frequency scale of the dynamics, the QND coupling induces an effective dephasing in the adiabatic basis. Optimal conditions for adiabaticity are found when the coupling with the meter induces dissipative dynamics which suppresses unwanted diabatic transitions.