Molecular wires acting as coherent quantum ratchets.

Area of Science:

• Quantum transport phenomena
• Molecular electronics
• Laser-matter interactions

Background:

• Electron transport in molecular wires is crucial for nanoelectronic devices.
• Quantum effects like coherence and rectification are key to molecular functionalities.
• External fields can modulate quantum transport properties.

Purpose of the Study:

• Investigate the influence of laser fields on electron transport through molecular wires.
• Characterize the molecular wire as a coherent quantum ratchet and rectifier.
• Analyze the nonlinear current response under laser irradiation.

Main Methods:

• Theoretical investigation of electron transport.
• Modeling molecular wires with asymmetric chemical groups.
• Utilizing the Floquet basis for driven quantum systems.
• Closed-form evaluation of nonlinear current.

Main Results:

• A molecular wire with asymmetric groups functions as a quantum rectifier.
• A finite DC response is observed without static bias.
• Multiple current reversals occur with varying laser amplitude and frequency.
• Current saturates for long wires and can change sign with length.

Conclusions:

• Laser fields can induce and control rectification in molecular wires.
• The quantum ratchet effect enables bias-free DC current generation.
• Molecular wire length and laser parameters critically affect current direction and magnitude.