Rabi Regime of Current Rectification in Solids

Area of Science:

• Condensed matter physics
• Quantum optics
• Non-equilibrium statistical mechanics

Background:

• Investigating charge transport in systems with broken symmetries under external fields is crucial.
• Perturbation theory suggests rectified currents diverge in clean systems, posing a theoretical challenge.

Purpose of the Study:

• To resolve the apparent divergence of rectified currents in the clean limit.
• To characterize the behavior of rectified currents in systems lacking inversion and time-reversal symmetries under oscillating electric fields.
• To establish a theoretical framework interpolating between closed and open quantum systems.

Main Methods:

• Utilizing the nonequilibrium Green function technique.
• Applying Floquet theory to analyze systems under periodic driving.
• Developing a theoretical description for weak coupling to a thermal bath.

Main Results:

• Rectified currents do not diverge in the clean limit; instead, a periodic steady state emerges.
• This steady state exhibits Rabi oscillations, leading to finite rectified currents.
• The rectified current in the Rabi regime scales with the square root of radiation intensity, distinct from the linear scaling in the perturbative regime.

Conclusions:

• The apparent divergence of rectified currents is an artifact of perturbation theory.
• A well-defined Rabi regime with finite rectified currents exists in weakly coupled systems.
• The developed theory smoothly connects closed system Rabi oscillations to the perturbative regime of strongly coupled systems.