Radiative Auger process in the single-photon limit

Abstract

In a multi-electron atom, an excited electron can decay by emitting a photon. Typically, the leftover electrons are in their ground state. In a radiative Auger process, the leftover electrons are in an excited state and a red-shifted photon is created [1][2][3][4] . In a quantum dot, radiative Auger is predicted for charged excitons 5 . Here, we report the observation of radiative Auger on trions in single quantum dots. For a trion, a photon is created on electron-hole recombination, leaving behind a single electron. The radiative Auger process promotes this additional (Auger) electron to a higher shell of the quantum dot. We show that the radiative Auger effect is a powerful probe of this single electron: the energy separations between the resonance fluorescence and the radiative Auger emission directly measure the single-particle splittings of the electronic states in the quantum dot with high precision. In semiconductors, these single-particle splittings are otherwise hard to access by optical means as particles are excited typically in pairs, as excitons. After the radiative Auger emission, the Auger carrier relaxes back to the lowest shell. Going beyond the original theoretical proposals, we show how applying quantum optics techniques to the radiative Auger photons gives access to the single-electron dynamics, notably relaxation and tunnelling. This is also hard to access by optical means: even for quasi-resonant p-shell excitation, electron relaxation takes place in the presence of a hole, complicating the relaxation dynamics. The radiative Auger effect can be exploited in other semiconductor nanostructures and quantum emitters in the solid state to determine the energy levels and the dynamics of a single carrier.

Charge Tunable GaAs Quantum Dots in a Photonic n-i-p Diode

“…Such a bimodal distribution is related to the wavelength-dependent optical properties of the low-noise GaAs QDs mentioned above [1]. The results extend to GaAs QDs used in other publications, as similar growth parameters were used [18,19].…”

Low-noise GaAs quantum dots for quantum photonics

“…f Auto-correlation of the resonance fluorescence measured under weak continuous-wave excitation shown on a short timescale. The g (2) -measurement is normalised 44 by dividing the number of coincidences by its expectation value…”

“…2g). (We note that our analysis includes a mathematically justified normalisation of the g (2) -measurement 44 ). This result demonstrates that blinking is absent.…”

“…f Auto-correlation of the resonance fluorescence measured under weak continuous-wave excitation shown on a short time-scale. The g (2) -measurement is normalised 44 by dividing the number of coincidences by its expectation value T ⋅ t bin ⋅ x 1 ⋅ x 2 , where T is the overall integration time, t bin is the binning time, and x 1 , x 2 are the count-rates on the two single-photon detectors. g The same auto-correlation measurement as in f but evaluated on a much longer time-scale (milliseconds).…”

An Efficient Hole Transporting Polymer for Quantum Dot Light‐Emitting Diodes

“…[ 8,11–14 ] It results in unbalanced charge carriers inside the QD EMLs since zinc oxide nanoparticles (ZnO NPs) with high electron conductivities and suitable conduction bands are used as the electron transporting layers (ETLs), [ 15,16 ] significantly increasing the exciton quenching inside QD EMLs through non‐radiative channels and restricting the efficiencies of QLEDs. [ 17–19 ]…”