Strong Quantum Coherence between Fermi Liquid Mahan Excitons

J. Paul, C. E. Stevens, C. Liu, P. Dey, C. McIntyre, V. Turkowski, J. L. Reno, D. J. Hilton, and D. Karaiskaj

Phys. Rev. Lett. 116, 157401 – Published 14 April 2016

Abstract

In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called “Mahan excitons.” The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.

Received 6 August 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.157401

Physics Subject Headings (PhySH)

Excitons Quantum coherence & coherence measures Ultrafast phenomena

Quantum wells

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

J. Paul¹, C. E. Stevens¹, C. Liu¹, P. Dey¹, C. McIntyre¹, V. Turkowski², J. L. Reno³, D. J. Hilton⁴, and D. Karaiskaj^1,*

¹Department of Physics, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA
²Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
³CINT, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
⁴Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA