Ultrafast electric phase control of a single exciton qubit

Abstract

We report on the coherent phase manipulation of quantum dot excitons by electric means. For our experiments, we use a low capacitance single quantum dot photodiode which is electrically controlled by a custom designed SiGe:C BiCMOS chip. The phase manipulation is performed and quantified in a Ramsey experiment, where ultrafast transient detuning of the exciton energy is performed synchronous to double pulse π/2 ps laser excitation. We are able to demonstrate electrically controlled phase manipulations with magnitudes up to 3π within 100 ps which is below the dephasing time of the quantum dot exciton.

Electron and Hole g Tensors of Neutral and Charged Excitons in Single Quantum Dots by High-Resolution Photocurrent Spectroscopy

“…Photocurrent (PC) spectroscopy of a single QD embedded in a diode has been proved an effective way to read out the charge [27] and the spin [28,29] information from a single QD directly with high detection efficiency [30]. Compared with photoluminescence (PL) by non-resonant pumping, the PC spectroscopy has a higher resolution with continuous-wave (CW) resonant pumping, and can be used in the coherent control with pulsed pumping [31][32][33][34][35][36]. On the other hand, the detection of PC signal doesn't need to filter the pumping laser like resonant fluorescence, which is convenient to research the spin properties.…”

Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots

“…Photons emitted by this process are highly entangled and indistinguishable [21][22][23], but again the simultaneous resonant excitation and emission needs to be avoided. In the light of recent experimental and technological developments, which demonstrated fast electrical control of electronic resonances [24] and coherent control of excitonic states [25], we propose and theoretically explore an optoelectronic scheme to excite the quantum dot exciton and biexciton, from which photons can then efficiently and resonantly be emitted into a cavity mode. The proposed scheme does not use phonon side bands [13,14], optical Stark-shifts [26], or the biexciton-exciton emission cascade.…”

Time-frequency encoded single-photon sources and broadband quantum memories based on a tunable one-dimensional atom

“…The new concepts introduced here are applicable to all kinds of coupled natural or artificial atoms. They are ready to be implemented in the semiconductor platform for quantum light generation based on quantum dots, where all basic ingredients have individually been demonstrated [11][12][13][14]31].…”