Coherent two-exciton dynamics measured using two-quantum rephasing two-dimensional electronic spectroscopy

Abstract

We use fifth-order two-dimensional electronic spectroscopy to measure coherent four-particle dynamics in a semiconductor nanostructure. By using optical polarization control in two-quantum measurements enabled by the COLBERT spectrometer, we separate coherent signals due to bound biexcitons and unbound two-exciton correlations. The rephasing nature of the measurement allows us to separate homogeneous from inhomogeneous contributions to the two-quantum lineshapes. We find that, unlike the bound biexciton state, the energy of the unbound pair and its homogeneous linewidth depend on the laser fluence. Simulations using an extended phenomenological model help determine the primary interaction mechanism that leads to the formation of the unbound exciton pair; the model also indicates that seventh-order interactions contribute to the measured spectra under high pulse fluences.

Crossing disciplines ‐ A view on two‐dimensional optical spectroscopy

“…Both transient absorption and 2D spectroscopy use a four‐wave mixing process, which involves the third‐order nonlinear optical susceptibility χ (3) . (Higher‐order nonlinearities have been used in 2D spectroscopy measurements as well . Here we focus on signals from third‐order nonlinearities.)…”

Dephasing effects on coherent exciton-polaritons and the breakdown of the strong coupling regime

“…In this Appendix, we present the explicit forms of the coupled-mode equations [31,32] used to simulate the pumpprobe spectra. We restrict the number of modes to the three main ones: pump, probe, and idler.…”

“…The pump and probe pulses are introduced as E pu and E pr respectively and the transmitted probe signal is obtained through E pr . This is the standard method of calculating a transient four-wave mixing signal in optical Bloch equations [31,32]. Since the wave number of the probe is sufficiently small, we neglect the momentum dispersion of the photon mode.…”

Persistent exciton-type many-body interactions in GaAs quantum wells measured using two-dimensional optical spectroscopy

“…GaAs quantum wells were studied extensively 2-33 throughout the 1980s and 1990s, primarily through fourwave mixing measurements, resulting in new insights about phenomena such as quantum beats, exciton dephasing times and mechanisms, disorder, and manybody interactions. The application of another fourwave mixing technique known as two-dimensional (2D) Fourier-transform optical spectroscopy heralded a new era of investigation [34][35][36][37][38][39][40][41][42][43][44][45] . To date, these nonlinear spectroscopy experiments have been understood using theoretical treatments at varying levels of sophistication.…”