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Register a new userPerformance of superadiabatic stimulated Raman adiabatic passage in the presence of dissipation and Ornstein-Uhlenbeck dephasing
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Dionisis Stefanatos
Publication date
2020
fields
Physics
and research's language is
English
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In this paper we evaluate the performance of two superadiabatic stimulated Raman adiabatic passage (STIRAP) protocols derived from Gaussian and sin-cos pulses, under dissipation and Ornstein-Uhlenbeck noise in the energy levels. We find that for small amplitudes of Stokes and pump pulses, the population transfer is mainly achieved directly through the counterdiabatic pulse, while for large amplitudes the conventional STIRAP path dominates. This kind of hedging leads to a remarkable robustness against dissipation in the lossy intermediate state. For small pulse amplitudes and increasing noise correlation time the performance is decreased, since the dominant counterdiabatic pulse is affected more, while for large pulse amplitudes, where the STIRAP path dominates, the efficiency is degraded more for intermediate correlation times (compared to the pulse duration). For the Gaussian superadiabatic STIRAP protocol we also investigate the effect of delay between pump and Stokes pulses and find that under the presence of noise the performance is improved for increasing delay. We conclude that the Gaussian protocol with suitably chosen delay and the sin-cos protocol perform quite well even under severe noise conditions. The present work is expected to have a broad spectrum of applications, since STIRAP has a crucial role in modern quantum technology.
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We present an analytic description of the effects of dephasing processes on stimulated Raman adiabatic passage in a tripod quantum system. To this end, we develop an effective two-level model. Our analysis makes use of the adiabatic approximation in the weak dephasing regime. An effective master equation for a two-level system formed by two dark states is derived, where analytic solutions are obtained by utilizing the Demkov-Kunike model. From these, it is found that the fidelity for the final coherent superposition state decreases exponentially for increasing dephasing rates. Depending on the pulse ordering and for adiabatic evolution the pulse delay can have an inverse effect.
We exploit a microscopically derived master equation for the study of STIRAP in the presence of decay from the auxiliary level toward the initial and final state, and compare our results with the predictions obtained from a phenomenological model previously used [P. A. Ivanov, N. V. Vitanov, and K. Bergmann, Phys. Rev. A 72, 053412 (2005)]. It is shown that our approach predicts a much higher efficiency. The effects of temperature are also taken into account, proving that in b-STIRAP thermal pumping can increase the efficiency of the population transfer.
We propose a technique which produces nearly complete ionization of the population of a discrete state coupled to a continuum by a two-photon transition via a lossy intermediate state whose lifetime is much shorter than the interaction duration. We show that using counterintuitively ordered pulses, as in stimulated Raman adiabatic passage (STIRAP), wherein the pulse coupling the intermediate state to the continuum precedes and partly overlaps the pulse coupling the initial and intermediate states, greatly increases the ionization signal and strongly reduces the population loss due to spontaneous emission through the lossy state. For strong spontaneous emission from that state, however, the ionization is never complete because the dark state required for STIRAP does not exist. We demonstrate that this drawback can be eliminated almost completely by creating a laser-induced continuum structure (LICS) by embedding a third discrete state into the continuum with a third control laser. This LICS introduces some coherence into the continuum, which enables a STIRAP-like population transfer into the continuum. A highly accurate analytic description is developed and numerical results are presented for Gaussian pulse shapes.
The theory of stimulated Raman adiabatic passage in a three-level Lambda-scheme of the interaction of an atom or molecule with light, which takes the nonadiabatic processes at the beginning and the end of light pulses into account, is developed.
We present a general formalism for describing stimulated Raman adiabatic passage in a multi-level atom. The atom is assumed to have two ground state manifolds a and b and an excited state manifold e, and the adiabatic passage is carried out by resonantly driving the a-e and b-e transitions with time-dependent fields. Our formalism gives a complete description of the adiabatic passage process, and can be applied to systems with arbitrary numbers of degenerate states in each manifold and arbitrary couplings of the a-e and b-e transitions. We illustrate the formalism by applying it to both a simple toy model and to adiabatic passage in the Cesium atom.
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