The birth of a quasiparticle in silicon observed in time-frequency space

Article

关键词: RAMAN-SCATTERING;    TEMPERATURE-DEPENDENCE;    LIGHT-SCATTERING;    CRITICAL-POINTS;    FREE-CARRIERS;    SI;    SEMICONDUCTORS;    INTERFERENCE;    ELECTRON;    BAND;   

DOI  :  10.1038/nature02044

来源: SCIE

【 摘 要 】

The concept of quasiparticles in solid-state physics is an extremely powerful tool for describing complex many-body phenomena in terms of single-particle excitations(1). Introducing a simple particle, such as an electron, hole or phonon, deforms a manybody system through its interactions with other particles. In this way, the added particle is 'dressed' or 'renormalized' by a self-energy cloud that describes the response of the many-body system, so forming a new entity - the quasiparticle. Using ultrafast laser techniques, it is possible to impulsively generate bare particles and observe their subsequent dressing by the many-body interactions ( that is, quasiparticle formation) on the time and energy scales governed by the Heisenberg uncertainty principle(2). Here we describe the coherent response of silicon to excitation with a 10-femtosecond (10(-14) s) laser pulse. The optical pulse interacts with the sample by way of the complex second-order nonlinear susceptibility to generate a force on the lattice driving coherent phonon excitation. Transforming the transient reflectivity signal into frequency - time space reveals interference effects leading to the coherent phonon generation and subsequent dressing of the phonon by electron - hole pair excitations.

【 授权许可】

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