Λ-Processes Induced by Chirped Lasers

Lefkidis, Georgios; Hübner, Wolfgang

doi:10.1007/978-3-319-07743-7_41

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…The optically-induced population transfer from the initial state to the target state can also be achieved via the Λ-process (a generalized three-level system) under the properly tailored laser pulses [10,11,28], in which the frequency of the (quasi) Rabi oscillation depends on the amplitude of the laser, and the closer the laser frequency is to the energy gap between the initial (final) and intermediate states, the more efficiently population is transferred to the final state. The analytical discussion of the laser-induced spin flip can be found in [10,29]. If the system is only driven by thermal excitations, i.e., coupling to the thermal bath, for  ¥ t it will eventually reach a Boltzmann distribution determined by the temperature T, while the relaxation time will be determined by the coupling strength.…”

Section: Introductionmentioning

confidence: 99%

Optically- and thermally-induced electronic transitions in a three-level system

Qiu¹,

Jin²,

Qu³

et al. 2020

Phys. Scr.

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In this article , using the Lindblad-superoperator formalism, we study the laser-induced electronic transitions of a Λ process in a three-level model system coupled to an external thermal bath. We find that, with respect to the population transfer from the initial to the final state, when the two branches of the thermal transitions (i.e., initial to intermediate state and intermediate to final state) are symmetric, the unbalanced optical channels can enhance the fidelity of the dynamics. Especially for the case where one of the two optical branches is totally forbidden, the fidelity still reaches the maximal value due to the compensation by the thermal transition channel, leading to a population trapping in the final state (thermally assisted Λ process). On the other hand, with the increase of the unbalanced thermal channels in the case of symmetric optical transitions, the fidelity of the process does not change but the speed for the dynamics to reach the steady state slows down. Additionally, we investigate and analyze the role of the bath temperature, of the coupling constant to the thermal bath, as well as of a time-dependent energy shifting of the final state. For the last aspect, followed by the detailed symmetry analysis, its application on a realistic Ni2 molecule is presented. The results are expected to be highly relevant to the active manipulation of spins in real nanospintronic devices at room temperature.

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Section: Introductionmentioning

confidence: 99%

Optically- and thermally-induced electronic transitions in a three-level system

Qiu¹,

Jin²,

Qu³

et al. 2020

Phys. Scr.

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“…Instead, it induces i | ↓ ⟩ → boldY prefix− | ↑ ⟩ . This differs substantially from a simple spin flip and can be achieved by introducing the necessary time-reversal symmetry breaking in the laser pulse through chirp. , As it turns out, chirp “pushes” the phase of a Bloch oscillation or a Λ process in one direction in an asymmetric way, different from simple detuning . The spin-flip processes realized between the states |11⟩ and |12⟩ complete within 950 and 916 fs with fidelities of 96.98% and 96.24%, respectively.…”

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confidence: 99%

Optically Driven Both Classical and Quantum Unary, Binary, and Ternary Logic Gates on Co-Decorated Graphene Nanoflakes

Zhang,

Xu,

Liu

et al. 2023

J. Phys. Chem. Lett.

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“…In order to realize the spin–charge gearbox we need laser pulses that transfer electrons from one Co to another without flipping their spins (spin-transfer processes). Using our specially developed genetic algorithm, which was extended to include elliptically polarized as well as linearly chirped laser pulses, , we are able to find elementary spin-transfer Λ processes for all spin localizations; in other words, we can transfer the spin from every Co atom to every other Co atom always with a fidelity higher than 90%. Armed with these elementary processes we proceed to the realization of the spin gear box (Figure ).…”

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confidence: 99%