Ultrafast room-temperature valley manipulation in silicon and diamond

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Information Science

Background:

• Semiconductors possess unique electronic properties due to conduction band minima called valleys.
• Controlling electron populations in these valleys is crucial for developing advanced electronic devices.
• Existing methods for valley manipulation are limited, especially in technologically important bulk semiconductors.

Purpose of the Study:

• To demonstrate a universal and fast method for controlling and reading the valley quantum number of electrons.
• To enable valley population control in bulk semiconductors for potential applications in valleytronics.
• To advance the development of room-temperature valleytronic devices operating at terahertz frequencies.

Main Methods:

• Utilized an ultrafast technique involving unidirectional intervalley scattering.
• Employed an oscillating electric field from linearly polarized infrared femtosecond pulses.
• Achieved subpicosecond timescales for generation and read-out of valley-polarized electron populations.

Main Results:

• Successfully demonstrated an ultrafast technique for generating and reading valley-polarized electron populations in bulk semiconductors.
• Achieved control on subpicosecond timescales, significantly faster than previous methods.
• Established the principle based on unidirectional intervalley scattering induced by tailored light fields.

Conclusions:

• The developed technique offers a promising pathway for controlling electron valley populations in semiconductors.
• This method is compatible with silicon-based technology and operates at room temperature.
• The findings pave the way for terahertz-frequency valleytronic devices.