THz Near-Field Imaging of Unconventional Superconductors

Superconducting materials are the heart of the modern quantum technologies including quantum computation with its main workhorse - superconducting qubits, magnetic flux and voltage quantum metrology with Josephson junctions and superconducting quantum interference devices.

Hence the formidable effort to raise the superconducting transition temperature by researching new materials and superconductivity mechanisms beyond the standard Bardeen-Cooper-Schrieffer (BCS) model.

On the other hand, the new superconductivity-based technologies emerge as the phenomenon is becoming more investigated and better understood.

The coupling of THz frequency electromagnetic waves with superconducting matter and the emerging possibility of THz field generation, manipulation and detection via light-matter interactions in superconductors is the prime example .

Superconductors present a wide playground for the future single-chip THz technology due to the rich electromagnetic response involving nonlinear processes.

While the far-field THz nonlinearities in superconductors are being extensively studied for THz applications, the near-field nonlinear THz imaging would provide an insight to the superconducting excitations inaccessible in the linear regime and with high spatiotemporal resolution.

In fact, the THz-frequency electromagnetic radiation represents a peculiar energy scale of important condensed matter excitations - interaction mediators in correlated electron systems (e.g. phonons for Cooper pairs in BCS superconductors), making them an indispensable probe for other electron - electron coupling mechanisms in unconventional correlated systems.

This project is aimed at (i) implementation of a nonlinear spatiotemporal near-field imaging technique, and its application to the investigation of nanoscale-picosecond THz response of the two fascinating superconducting systems: (ii) high-Tc layered cuprates, (iii) the magic-angle twisted bilayer graphene.