Abstract: Electron pairing in most conventional superconductors results in translationally invariant charged superfluids. However, by coupling with density wave orders, electron pairs can form crystalline states known as pair density waves (PDWs) that break translational symmetry. Experimental evidence of
such exotic states remains scarce due to technical difficulties in probing the superconducting condensate with sufficient spatial resolution. In this talk, I will introduce our recent discovery of PDW states in two dichalcogenide superconductors (NbSe2, UTe2) using superconductive tips in a scanning
tunneling microscope [1,2]. Using the same technique, I will then discuss our capability in mapping the velocity field of electron-pair fluid around quantum vortices . Finally, I will share my perspective on applications of such techniques in other emerging quantum materials.
 Q Gu, J. P. Carroll, S. Wang, S. Ran, C. Broyles, H. Siddiquee, N. P. Butch, S. R. Saha, J. Paglione, J. C. Séamus Davis, and X. Liu. arXiv:2209.10859 (2022).
 X. Liu, Y. X. Chong, R. Sharma, and J.C. Séamus Davis, Science 372, 1447-1452 (2021).
 X. Liu, Y. X. Chong, R. Sharma, and J.C. Séamus Davis, Nat. Mater. 20, 1480–1484 (2021).