TY - JOUR

T1 - Radiative Auger process in the single-photon limit

AU - Lobl, Matthias C.

AU - Spinnler, Clemens

AU - Javadi, Alisa

AU - Zhai, Liang

AU - Nguyen, Giang N.

AU - Ritzmann, Julian

AU - Midolo, Leonardo

AU - Lodahl, Peter

AU - Wieck, Andreas D.

AU - Ludwig, Arne

AU - Warburton, Richard J.

N1 - Hy Q

PY - 2020/7

Y1 - 2020/7

N2 - In a radiative Auger process, an excited electron relaxes by concomitant emission of a redshifted photon and energy transfer to another electron. Measuring radiative Auger processes in a quantum dot with single-photon resolution enables determination of the energy of single-electron levels as well as their lifetimes.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 redshifted photon is created(1-4). In a semiconductor 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-resonantp-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.

AB - In a radiative Auger process, an excited electron relaxes by concomitant emission of a redshifted photon and energy transfer to another electron. Measuring radiative Auger processes in a quantum dot with single-photon resolution enables determination of the energy of single-electron levels as well as their lifetimes.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 redshifted photon is created(1-4). In a semiconductor 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-resonantp-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.

KW - QUANTUM DOTS

KW - SHAKE-UP

KW - LUMINESCENCE

KW - TRANSITIONS

KW - EMISSION

U2 - 10.1038/s41565-020-0697-2

DO - 10.1038/s41565-020-0697-2

M3 - Journal article

C2 - 32541943

VL - 15

SP - 558

EP - 562

JO - Nature Nanotechnology

JF - Nature Nanotechnology

SN - 1748-3387

IS - 7

ER -