Femtosecond modulation of electron correlations in a Luttinger liquid
- Na Li
- Umang Mehta
- Matin Lebrat
- Shunye Gao
- Tika Kafle
- Richa Sapkota
- Henry C. Kapteyn
- Oscar Granas
- Rahul Nandkishore
- Margaret M. Murnane
2026-05-27
Luttinger liquids emerge in one-dimensional metals with strong electron interactions, exhibiting intriguing near-equilibrium properties such as spin-charge separation and power-law correlations. Although these interactions suggest fast, distinctive out-of-equilibrium dynamics, such phenomena remain largely unexplored on ultrashort timescales. Here, we use femtosecond laser excitation to weakly deplete the electron density in the Luttinger band of Li 0.9 Mo 6 O 17 and track the response via time- and angle-resolved photoemission spectroscopy. By fitting the measured electron distributions to a finite-temperature Luttinger liquid model, we observe a fast drop in the Luttinger exponent, quantifying the strength of electron interactions. Subsequently, unlike hot electrons in conventional Fermi liquids that slowly relax within picoseconds via electron-phonon coupling, hot electrons in Li 0.9 Mo 6 O 17 relax within a short time of ~100 femtoseconds, through the excitation of a nonequilibrium collective plasmon. The extremely fast evolution of the Luttinger exponent and electron temperature—including a tens of femtosecond time lag between excitation, recovery, and plasmon-driven modulation—reveals previously unidentified pathways for modulating quantum many-body interactions in low-dimensional materials.