5 research outputs found
Optically driving the radiative Auger transition
In a radiative Auger process, optical decay is accompanied by simultaneous
excitation of other carriers. The radiative Auger process gives rise to weak
red-shifted satellite peaks in the optical emission spectrum. These satellite
peaks have been observed over a large spectral range: in the X-ray emission of
atoms; close to visible frequencies on donors in semiconductors and quantum
emitters; and at infrared frequencies as shake-up lines in two-dimensional
systems. So far, all the work on the radiative Auger process has focussed on
detecting the spontaneous emission. However, the fact that the radiative Auger
process leads to photon emission suggests that the transition can also be
optically excited. In such an inverted radiative Auger process, excitation
would correspond to simultaneous photon absorption and electronic
de-excitation. Here, we demonstrate optical driving of the radiative Auger
transition on a trion in a semiconductor quantum dot. The radiative Auger and
the fundamental transition together form a -system. On driving both
transitions of this -system simultaneously, we observe a reduction of
the fluorescence signal by up to . Our results demonstrate a type of
optically addressable transition connecting few-body Coulomb interactions to
quantum optics. The results open up the possibility of carrying out THz
spectroscopy on single quantum emitters with all the benefits of optics:
coherent laser sources, efficient and fast single-photon detectors. In analogy
to optical control of an electron spin, the -system between the
radiative Auger and the fundamental transitions allows optical control of the
emitters' orbital degree of freedom.Comment: 8 pages, 6 figure
Narrow optical linewidths and spin pumping on charge-tunable close-to-surface self-assembled quantum dots in an ultrathin diode
We demonstrate full charge control, narrow optical linewidths, and optical spin pumping on single self-assembled InGaAs quantum dots embedded in a 162.5ânm-thin diode structure. The quantum dots are just 88nm from the top GaAs surface. We design and realize a pâiânâiân diode that allows single-electron charging of the quantum dots at close-to-zero applied bias. In operation, the current flow through the device is extremely small resulting in low noise. In resonance fluorescence, we measure optical linewidths below 2ÎŒeV, just a factor of 2 above the transform limit. Clear optical spin pumping is observed in a magnetic field of 0.5T in the Faraday geometry. We present this design as ideal for securing the advantages of self-assembled quantum dotsâhighly coherent single-photon generation, ultrafast optical spin manipulationâin the thin diodes required in quantum nanophotonics and nanophononics applications
Quantum interference of identical photons from remote GaAs quantum dots
Photonic quantum technology provides a viable route to quantum communication1,2, quantum simulation3 and quantum information processing4. Recent progress has seen the realization of boson sampling using 20âsingle photons3 and quantum key distribution over hundreds of kilometres2. Scaling the complexity requires architectures containing multiple photon sources, photon counters and a large number of indistinguishable single photons. Semiconductor quantum dots are bright and fast sources of coherent single photons5,6,7,8,9. For applications, a roadblock is the poor quantum coherence on interfering single photons created by independent quantum dots10,11. Here we demonstrate two-photon interference with near-unity visibility (93.0â±â0.8)% using photons from two completely separate GaAs quantum dots. The experiment retains all the emission into the zero phonon lineâonly the weak phonon sideband is rejected; temporal post-selection is not employed. By exploiting quantum interference, we demonstrate a photonic controlled-not circuit and an entanglement with fidelity of (85.0â±â1.0)% between photons of different origins. The two-photon interference visibility is high enough that the entanglement fidelity is well above the classical threshold. The high mutual coherence of the photons stems from high-quality materials, diode structure and relatively large quantum dot size. Our results establish a platformâGaAs quantum dotsâfor creating coherent single photons in a scalable way
A Charge-Tunable Quantum Dot Deep in The Strong Coupling Regime of Cavity QED
International audienceWe present high-cooperativity (C up to 140) strong coupling of a charge-tunable InAs quantum dot embedded in a tunable Fabry-PĂ©rot microcavity (Q=500,000). Via second-order correlation measurements we show high single-photon purity in the photon-blockade regime and pronounced vacuum Rabi oscillations in the photon-induced tunneling regime