Harnessing Light for Valley Control in 2d Semiconductors

Abstract The presence of two degenerate unconventional quantum states, known as valleys, in 2D materials is often regarded as analogous to binary operational units – representing 0 and 1. These valley states can also exist in superposition, effectively functioning as qubits. The unique properties of valleys make 2D materials a viable possibility for integration into devices designed for coherent encoding, processing, and reading of both classical and quantum information. To realize such applications, precise control over valley states is essential, enabling the implementation of valley‐based devices for practical purposes. A novel approach was introduced to exercise necessary control in achieving valley polarization using a nonresonant single color linearly polarized laser pulse. By exploiting the asymmetric waveform of the linear pulse with skewed polarization, valley polarization was successfully induced. Remarkably, the method enables the complete reversal of valley polarization between valleys in 2D semiconductors. The asymmetric waveform also generates a valley current, which serves as a quantifiable marker for induced valley polarization. This approach provides a means to induce valley polarization, achieve its complete reversal, and quantify it through the associated valley current. The present findings hold significant potential for advancing valleytronics at ambient conditions by showcasing an all‐optical approach to effectively harness and manipulate valley states in 2D semiconductors.