We have measured the collective excitation spectrum of interacting electrons in one-dimension. The experiment consists of controlling the energy and momentum of electrons tunneling between two clean and closely situated, parallel quantum wires in a GaAs/AlGaAs heterostructure while measuring the resulting conductance. We measure excitation spectra that clearly deviate from the non-interacting spectrum, attesting to the importance of Coulomb interactions. Notable is an observed 30% enhancement of the velocity of the main excitation branch relative to non-interacting electrons with the same density. In short wires, finite size effects resulting from broken translational invariance are observed. Spin-charge separation is manifested through moiré patterns reflecting different spin and charge excitation velocities.
Bibliographical noteFunding Information:
This work was supported in part by the US-Israel BSF, the European Commission RTN Network Contract No. HPRN-CT-2000-00125 and NSF Grant DMR 02-33773. YT is supported by the Harvard Society of Fellows.
- A. Nanostructures
- D. Electron-electron interactions
- D. Electronic transport
- D. Tunnelling