Photonic circuits with multiple quantum dots: Towards scalable operation of deterministic single-photon sources
Research output: Book/Report › Ph.D. thesis › Research
Single photons represent a major asset for the development of quan-
tum technologies, owing to their compatibility with advanced photonic integrated circuits, ultimately enabling the realization of large-scale quantum processors. Generating the necessary large photonic resource requires scaling up integrated deterministic single-photon sources (SPS), a challenging task due to emitter-to-emitter disparity in wavelength and position.
Here, we experimentally implement a strategy to control multiple solidstate quantum emitters directly integrated into photonic circuits, to generate multi-photon states on-chip.
More specifically, we employ low-noise InAs quantum dots (QD) inte-
grated into p-i-n GaAs nanophotonic waveguides, which have been developed over the past few years to generate indistinguishable single photons.
The strong-light matter interaction in nanophotonic structures ensures deterministic operation, leading to a high single-photon count rate. Additionally, the planar quantum photonic platform offers the opportunity to integrate the control of SPSs through dedicated circuits, ultimately enabling the realization of a multi-QD circuit.
We first demonstrate a small-scale multi-QD photonic circuit enabling the simultaneous operation of two waveguide-integrated SPSs. To do so, we make use of dual-mode waveguides, where one mode is used for ex-
citation and the second one for collecting single photons, enabling fully waveguide-based resonant excitation and laser filtering. We optically address these two "plug-and-play" SPSs in parallel using a polarization diversity grating to perform on-chip distribution of a single laser to two QDs.
The pair of quantum dots are brought into mutual resonance by applying independent bias voltages across the p-i-n diode with locally-isolated electrical contacts, thereby tuning the QDs emission wavelength individually.
Each of the waveguide-integrated QDs exhibit excellent single-photon generation as characterized by g(2)(0) ≪ 0.5. Two-photon quantum interference between the two mutually resonant QDs is measured, with a peak visibility of V = 79 ± 2%, limited by imperfect laser suppression.
To overcome this limit, mainly caused by fabrication disorder, we investigate a novel scheme for preparing the mode for excitation in a dualmode waveguide based on asymmetric directional couplers. Owing to the bi-directionality of the single-photon emission, this device represents a natural source of dual-rail encoded qubits emitted by a single QD. This is confirmed by measuring the second-order correlation at the device output ports, characterized by a g(2)(0) < 0.07 in deterministic pulsed excitation.
The results demonstrated in this thesis embody a strategy for integrating multiple quantum emitters in photonic integrated circuits, with foreseeable application in quantum simulation and quantum communication.
tum technologies, owing to their compatibility with advanced photonic integrated circuits, ultimately enabling the realization of large-scale quantum processors. Generating the necessary large photonic resource requires scaling up integrated deterministic single-photon sources (SPS), a challenging task due to emitter-to-emitter disparity in wavelength and position.
Here, we experimentally implement a strategy to control multiple solidstate quantum emitters directly integrated into photonic circuits, to generate multi-photon states on-chip.
More specifically, we employ low-noise InAs quantum dots (QD) inte-
grated into p-i-n GaAs nanophotonic waveguides, which have been developed over the past few years to generate indistinguishable single photons.
The strong-light matter interaction in nanophotonic structures ensures deterministic operation, leading to a high single-photon count rate. Additionally, the planar quantum photonic platform offers the opportunity to integrate the control of SPSs through dedicated circuits, ultimately enabling the realization of a multi-QD circuit.
We first demonstrate a small-scale multi-QD photonic circuit enabling the simultaneous operation of two waveguide-integrated SPSs. To do so, we make use of dual-mode waveguides, where one mode is used for ex-
citation and the second one for collecting single photons, enabling fully waveguide-based resonant excitation and laser filtering. We optically address these two "plug-and-play" SPSs in parallel using a polarization diversity grating to perform on-chip distribution of a single laser to two QDs.
The pair of quantum dots are brought into mutual resonance by applying independent bias voltages across the p-i-n diode with locally-isolated electrical contacts, thereby tuning the QDs emission wavelength individually.
Each of the waveguide-integrated QDs exhibit excellent single-photon generation as characterized by g(2)(0) ≪ 0.5. Two-photon quantum interference between the two mutually resonant QDs is measured, with a peak visibility of V = 79 ± 2%, limited by imperfect laser suppression.
To overcome this limit, mainly caused by fabrication disorder, we investigate a novel scheme for preparing the mode for excitation in a dualmode waveguide based on asymmetric directional couplers. Owing to the bi-directionality of the single-photon emission, this device represents a natural source of dual-rail encoded qubits emitted by a single QD. This is confirmed by measuring the second-order correlation at the device output ports, characterized by a g(2)(0) < 0.07 in deterministic pulsed excitation.
The results demonstrated in this thesis embody a strategy for integrating multiple quantum emitters in photonic integrated circuits, with foreseeable application in quantum simulation and quantum communication.
Original language | English |
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Publisher | Niels Bohr Institutet |
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Number of pages | 146 |
Publication status | Published - 2023 |
ID: 347422034