Browsing by Subject "Quantum beats"

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    Quantum Beats between Spin-Singlet and Spin-Triplet Interlayer Exciton Transitions in WSe2-MoSe2 Heterobilayers
    (American Chemical Society, 2024-04-19) Durmuş, Mehmet Atıf; Sarpkaya, İbrahim
    The long-lived interlayer excitons (IXs) of semiconducting transition metal dichalcogenide heterobilayers are prime candidates for developing various optoelectronic and valleytronic devices. Their photophysical properties, including fine structure, have been the focus of recent studies, and the presence of two spin states, namely, spin-singlet and spin-triplet, has been experimentally confirmed. However, the existence of the interaction between these states and their nature remains unknown to date. Here, we demonstrate the presence of coherent coupling between the spin-singlet and spin-triplet IXs of a WSe2-MoSe2 heterobilayer utilizing quantum beat spectroscopy via a home-built Michelson interferometer. As a clear signature of coherent coupling, the quantum beat signal has been observed for the first time between closely spaced transitions of IXs. The observed strong damping of the quantum beat signals with fast dephasing times of 270-400 fs indicates that fluctuations giving rise to inhomogeneous broadening in the photoluminescence emission of these states are uncorrelated.
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    Temperature-dependent quantum beats between neutral and charged excitons in monolayer MoSe2
    (The Scientific and Technological Research Council of Tuerkiye - TUBITAK,Turkiye Bilimsel ve Teknik Arastirma Kurumu, 2024-09-26) Sarpkaya, İbrahim
    We studied the interaction between the neutral and charged excitons of monolayer MoSe 2 at various temperatures via quantum beat spectroscopy in the time domain. We introduced temperature as an efficient control knob to regulate the relative photoluminescence intensities of the neutral and charged excitons to obtain maximum quantum beat resolution. Furthermore, our quantum beat measurements under different temperatures indicate that the decoherence time of the coupled exciton-trion state slightly decreases from 530 fs at 3.5 K to 420 fs at 63 K with increased temperature due to the low-energy acoustic phonon-induced dephasing.