Nonlinear Terahertz Electroluminescence from Dirac-Landau Polaritons

Area of Science:

• Condensed matter physics
• Quantum optics
• Terahertz (THz) spectroscopy

Background:

• Two-dimensional Dirac fermions in HgTe quantum wells exhibit unique electronic properties.
• Strong coupling between electronic excitations and optical cavity modes is crucial for quantum technologies.

Purpose of the Study:

• To investigate Dirac-Landau polaritons formed by coupling Dirac fermions with optical cavity modes.
• To explore nonlinear electroluminescence and potential for polariton condensation and lasing in the THz range.

Main Methods:

• Terahertz (THz) magnetoreflectivity spectroscopy was employed to observe Dirac-Landau polaritons.
• Pulsed electrical injection was used to induce nonlinear electroluminescence.
• Model analysis of emission intensity and spectral narrowing provided insights into polariton occupancy.

Main Results:

• Strong coupling between cyclotron transitions of 2D Dirac fermions and optical cavity modes was demonstrated.
• Efficient nonlinear electroluminescence was observed under electrical injection, with a non-equilibrium polariton distribution.
• Polariton occupancy per mode approached unity, suggesting stimulated polariton emission.

Conclusions:

• The study successfully observed Dirac-Landau polaritons, confirming strong coupling in HgTe quantum wells.
• Results indicate potential for achieving Dirac-Landau polariton condensates.
• The findings pave the way for developing low-threshold, tunable THz polariton lasers.