Abstract
Solid-state quantum emitters are excellent sources of on-demand indistinguishable or entangled photons and can host long-lived spin memories, crucial resources for photonic quantum information applications. However, their scalability remains an outstanding challenge. Here we present a scalable technique to multiplex streams of photons from multiple independent quantum dots, on-chip, into a fiber network for use off-chip. Multiplexing is achieved by incorporating a multi-core fiber into a confocal microscope and spatially matching the multiple foci, seven in this case, to quantum dots in an array of deterministically positioned nanowires. First, we report the coherent control of the emission of biexciton-exciton cascade from a single nanowire quantum dot under resonant two-photon excitation. Then, as a proof-of-principle demonstration, we perform parallel spectroscopy on the nanowire array to identify two nearly identical quantum dots at different positions which are subsequently tuned into resonance with an external magnetic field. Multiplexing of background-free single photons from these two quantum dots is then achieved. Our approach, applicable to all types of quantum emitters, can readily be scaled up to multiplex $>100$ quantum light sources, providing a breakthrough in hardware for photonic based quantum technologies. Immediate applications include quantum communication, quantum simulation, and quantum computation.
Highlights
Motivated by the phenomenal scalability of semiconductor integrated circuits for classical computing and communication, semiconductor quantum photonic chips have been pursued for light-based quantum-information technologies
We take advantage of this to rapidly scan the quantum-emitter array and identify two quantum dots (QDs) with ground-state emissions separated by just 0.113 meV, which we subsequently tune into resonance with an external magnetic field
We address the nanowires in the multispot microscope using aboveband (1.4938-eV) excitation and find two QDs with similar exciton emissions with an energy difference of 0.113 meV
Summary
Motivated by the phenomenal scalability of semiconductor integrated circuits for classical computing and communication, semiconductor quantum photonic chips have been pursued for light-based quantum-information technologies. Quantum-information protocols such as quantum key distribution [23] (including measurement-deviceindependent schemes [24]), boson sampling [25,26], and photonic cluster state generation for measurement-based quantum computing [27,28,29] all benefit from having multiple streams of indistinguishable photons that can be realized with QDs. while each independent ingredient of the fully integrated chip vision has been realized separately, hybrid integration of all components in a fully functional platform is a demanding long-term challenge. We take advantage of this to rapidly scan the quantum-emitter array and identify two QDs with ground-state emissions separated by just 0.113 meV, which we subsequently tune into resonance with an external magnetic field By exciting both QDs individually, we observe suppressed multiphoton emission probability in the emission from both QDs, which validates the generation of single photons from remote emitters on the same chip. Our results motivate the integration of both coherent excitation and parallel spectroscopy to generate streams of indistinguishable single photons from multiple emitters on the same chip, which are crucial resources for photonic quantum technologies
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