Petahertz non-linear current in a centrosymmetric organic superconductor

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• Charge acceleration in solids under intense light fields is crucial for high-harmonic generation and photoelectron emission.
• Carrier-envelope-phase (CEP) control manipulates attosecond charge dynamics in various materials like insulators, nanometals, and graphene.
• Superconducting materials offer potential for collective charge motion control due to their coherent quasiparticle nature.

Purpose of the Study:

• To investigate the behavior of charge motion in superconducting materials under intense light fields.
• To explore the potential for controlling charge dynamics in superconductors using optical fields.
• To understand the underlying mechanisms of light-matter interactions in superconductors at petahertz frequencies.

Main Methods:

• Application of a single-cycle, 6-femtosecond near-infrared laser field to a layered organic superconductor.
• Observation and analysis of the generated nonlinear petahertz current.
• Quantum many-body analysis to interpret the experimental results.

Main Results:

• Observed second harmonic generation (SHG) from a nonlinear petahertz current, contradicting the expectation for centrosymmetric systems.
• Demonstrated that the SHG exhibits carrier-envelope-phase (CEP) sensitivity.
• Found an enhancement of SHG near the superconducting critical temperature, linked to superconducting fluctuations.

Conclusions:

• A polarized current is induced by nonlinear charge acceleration, amplified by superconducting fluctuations.
• This phenomenon enables petahertz functionalities in superconductors and strongly correlated systems.
• The findings open new avenues for ultrafast optoelectronics and quantum control in novel materials.