Coherent phonon flatband generated in GaAs/AlAs superlattices via layer-selective optical pumping

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Flatbands, with dispersionless energy levels, are crucial for electronics and quantum information processing.
• Existing flatbands are typically in thermal equilibrium, limiting external control and application flexibility.

Purpose of the Study:

• To demonstrate the generation of a switchable coherent phonon flatband.
• To explore a new method for creating and controlling flatbands outside of thermal equilibrium.

Main Methods:

• Utilized 800 nm femtosecond laser pulses to excite a GaAs/AlAs superlattice.
• Employed molecular dynamics simulations to analyze the excitation and flatband formation.
• Investigated the coupling between the generated flatband and existing phonon modes.

Main Results:

• Successfully generated a coherent phonon flatband in a GaAs/AlAs superlattice.
• The created flatband is not an equilibrium eigenmode and couples strongly with longitudinal phonon modes.
• Demonstrated that spatially modulated optical excitations can induce coherent phonon flatbands in superlattices.

Conclusions:

• A pathway for creating coherent phonon flatbands in the time domain has been established.
• This method offers enhanced control over flatbands, applicable beyond equilibrium states.
• The findings could inspire the generation of coherent flatbands for other quasiparticles, advancing quantum technologies.