Excitonic Bloch–Siegert shift in CsPbI3 perovskite quantum dots

Coherent interaction between matter and light field induces both optical Stark effect and Bloch–Siegert shift. Observing the latter has been historically challenging, because it is weak and is often accompanied by a much stronger Stark shift. Herein, by controlling the light helicity, we can largely...

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Published in:Nature communications 2022-09, Vol.13 (1), p.5559-5559, Article 5559
Main Authors: Li, Yuxuan, Han, Yaoyao, Liang, Wenfei, Zhang, Boyu, Li, Yulu, Liu, Yuan, Yang, Yupeng, Wu, Kaifeng, Zhu, Jingyi
Format: Article
Language:English
Subjects:
140/125
639/301/357/1017
639/766/400/2797
Data processing
Elementary excitations
Helicity
Humanities and Social Sciences
Information processing
Lead compounds
Light modulation
Many body problem
Metal halides
multidisciplinary
Perovskites
Quantum dots
Room temperature
Science
Science (multidisciplinary)
Spin transition
Spin transitions
Stark effect
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Summary:Coherent interaction between matter and light field induces both optical Stark effect and Bloch–Siegert shift. Observing the latter has been historically challenging, because it is weak and is often accompanied by a much stronger Stark shift. Herein, by controlling the light helicity, we can largely restrict these two effects to different spin-transitions in CsPbI 3 perovskite quantum dots, achieving room-temperature Bloch–Siegert shift as strong as 4 meV with near-infrared pulses. The ratio between the Bloch–Siegert and optical Stark shifts is however systematically higher than the prediction by the non-interacting, quasi-particle model. With a model that explicitly accounts for excitonic effects, we quantitatively reproduce the experimental observations. This model depicts a unified physical picture of the optical Stark effect, biexcitonic optical Stark effect and Bloch–Siegert shift in low-dimensional materials displaying strong many-body interactions, forming the basis for the implementation of these effects to information processing, optical modulation and Floquet engineering. Observation of a Bloch-Siegert shift has remained elusive. Here, Wu et al, reports spin-selective Bloch-Siegert shift in lead halide perovskite quantum dots, and highlights the importance of many-body interactions in correctly modeling the shift.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-022-33314-9