Abstract
The generation rate of entangled photons emitted from cascaded few-level systems is intrinsically limited by the lifetime of the radiative transitions. Here, we overcome this limit for entangled photon pairs from quantum dots via a novel driving regime based on an active reset of the radiative cascade. We show theoretically and experimentally the driving regime to enable the generation of entangled photon pairs with higher fidelity and intensity compared to the optimum continuously driven equilibrium state. Finally, we electrically generate entangled photon pairs with a total fidelity of $(79.5 \pm 1.1)\%$ at a record clock rate of 1.15GHz.
Highlights
Single and entangled photons promise unique advantages for many applications in quantum photonics, including enhanced secure key rates in quantum key distribution (QKD) through elimination of multiphoton emission [1], and global scale unconditionally secure networks with entanglementbased quantum repeaters [2]
We introduce a novel active reset (AR) driving scheme based on two core considerations: Firstly, to actively reset entanglement at a given clock cycle, the quantum dots (QDs) does not need to return to the ground state
The super-high-frequency driven (3.05 GHz) single photon LED and active reset driven (1.15 GHz) entangled LED results presented above impact other quantum emitter technology, those based on QDs
Summary
Single and entangled photons promise unique advantages for many applications in quantum photonics, including enhanced secure key rates in quantum key distribution (QKD) through elimination of multiphoton emission [1], and global scale unconditionally secure networks with entanglementbased quantum repeaters [2]. Clock rates achieved with entangled photons from QDs are much lower [15,16], impeding high frequency operation. We show that by pumping the system only for a fraction of the time, it is possible to access a regime where more entangled photon pairs are generated compared to keeping the system in an optimum continuously driven equilibrium state. This is made possible by employing a high-frequency pulsed excitation regime where the cycle is reset while still highly optically active, despite a reduced emission probability per clock cycle.
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