S. Groeblacher
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A quantum internet would enable capabilities that are provably impossible using only classical information.
In a future quantum internet, there is a need for an interface between spin-encoded qubits in network nodes and the photonic communication between them. The silicon T center is a promising candidate for use in such a spin-photon interface as it emits in the telecom O-band, has relatively long spin coherence in bulk Silicon-28 samples, and is compatible with the silicon-on-insulator (SOI) platform for easy manufacturing and scalability.
However, its relatively weak and slow emission makes characterization measurements time-consuming.
This thesis investigates how the T center count rate can be increased in confocal resonant excitation measurements. Two photonic structures are characterized: micropucks and bullseye cavities. Bullseyes are found to enhance zero-phonon line emission and are better suited for time-resolved measurements. Count rate estimates show that combining bullseye cavities with time-resolved interval photoluminescence excitation (TRIPLE) measurements can increase the signal-to-noise ratio by a factor of 2.4 compared to the conventional approach.
The TRIPLE setup is built, and a fluorescence lifetime of 620ns is measured in a bullseye structure using off-resonant excitation. Single T center resonant excitation has not yet been achieved, but the setup provides a strong foundation for future measurements. ...
In a future quantum internet, there is a need for an interface between spin-encoded qubits in network nodes and the photonic communication between them. The silicon T center is a promising candidate for use in such a spin-photon interface as it emits in the telecom O-band, has relatively long spin coherence in bulk Silicon-28 samples, and is compatible with the silicon-on-insulator (SOI) platform for easy manufacturing and scalability.
However, its relatively weak and slow emission makes characterization measurements time-consuming.
This thesis investigates how the T center count rate can be increased in confocal resonant excitation measurements. Two photonic structures are characterized: micropucks and bullseye cavities. Bullseyes are found to enhance zero-phonon line emission and are better suited for time-resolved measurements. Count rate estimates show that combining bullseye cavities with time-resolved interval photoluminescence excitation (TRIPLE) measurements can increase the signal-to-noise ratio by a factor of 2.4 compared to the conventional approach.
The TRIPLE setup is built, and a fluorescence lifetime of 620ns is measured in a bullseye structure using off-resonant excitation. Single T center resonant excitation has not yet been achieved, but the setup provides a strong foundation for future measurements. ...
A quantum internet would enable capabilities that are provably impossible using only classical information.
In a future quantum internet, there is a need for an interface between spin-encoded qubits in network nodes and the photonic communication between them. The silicon T center is a promising candidate for use in such a spin-photon interface as it emits in the telecom O-band, has relatively long spin coherence in bulk Silicon-28 samples, and is compatible with the silicon-on-insulator (SOI) platform for easy manufacturing and scalability.
However, its relatively weak and slow emission makes characterization measurements time-consuming.
This thesis investigates how the T center count rate can be increased in confocal resonant excitation measurements. Two photonic structures are characterized: micropucks and bullseye cavities. Bullseyes are found to enhance zero-phonon line emission and are better suited for time-resolved measurements. Count rate estimates show that combining bullseye cavities with time-resolved interval photoluminescence excitation (TRIPLE) measurements can increase the signal-to-noise ratio by a factor of 2.4 compared to the conventional approach.
The TRIPLE setup is built, and a fluorescence lifetime of 620ns is measured in a bullseye structure using off-resonant excitation. Single T center resonant excitation has not yet been achieved, but the setup provides a strong foundation for future measurements.
In a future quantum internet, there is a need for an interface between spin-encoded qubits in network nodes and the photonic communication between them. The silicon T center is a promising candidate for use in such a spin-photon interface as it emits in the telecom O-band, has relatively long spin coherence in bulk Silicon-28 samples, and is compatible with the silicon-on-insulator (SOI) platform for easy manufacturing and scalability.
However, its relatively weak and slow emission makes characterization measurements time-consuming.
This thesis investigates how the T center count rate can be increased in confocal resonant excitation measurements. Two photonic structures are characterized: micropucks and bullseye cavities. Bullseyes are found to enhance zero-phonon line emission and are better suited for time-resolved measurements. Count rate estimates show that combining bullseye cavities with time-resolved interval photoluminescence excitation (TRIPLE) measurements can increase the signal-to-noise ratio by a factor of 2.4 compared to the conventional approach.
The TRIPLE setup is built, and a fluorescence lifetime of 620ns is measured in a bullseye structure using off-resonant excitation. Single T center resonant excitation has not yet been achieved, but the setup provides a strong foundation for future measurements.
Master thesis
(2023)
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M.C. Dijksman, J. Borregaard, V. Dominguez Tubio, S. Groeblacher, M. Blaauboer
The distribution of multiple entangled pairs plays a vital role in various applications, such as quantum metrology, blind quantum computing, quantum key distribution, and quantum teleportation. While qubit-based protocols exist, they are often limited by short coherence times in quantum memories and the need for individual pair generation, leading to inefficiencies and reduced fidelity. To address these challenges, this thesis focuses on the development and analysis of a comprehensive theoretical framework for satellite-based entanglement distribution using high-dimensional qudits. By employing high-dimensional qudit encoding, which enables the simultaneous entanglement of multiple pairs, we aim to enhance the capacity and efficiency of entanglement distribution schemes.
The objectives of this research are twofold, first, to compare the performance of the qudit-based protocol with a similar qubit-based protocol, particularly in a satellite-based context, and second, to investigate the feasibility and potential advantages of employing high-dimensional qudit encoding for near-term long-range entanglement distribution. The theoretical framework encompasses various elements, including a single photon pair source, lossy transmission, mapping of qudit states to qubit memories, and heralding measurements.
Through various simulations, we evaluate the impact of different parameters on the performance of the proposed protocol. Our findings reveal that high-dimensional encoding significantly alleviates memory requirements, making it suitable for current technologies with low memory coherence times. Multiplexing techniques further enhance the achievable distances and transmission rates, highlighting their importance for realistic implementations. However, we note that higher-dimensional protocols introduce additional experimental challenges and errors, warranting further research and optimisation. Furthermore, we explore the effect of reducing dark count rates in detectors and analyse its influence on the overall performance. Our investigations underscore the need for substantial detector improvements, as current dark count probabilities are on the same order of magnitude as channel losses.
By advancing our understanding of satellite-based entanglement distribution using qudits, this research contributes to the development of practical and secure quantum communication networks. The results presented herein lay the groundwork for future advancements in quantum communication technologies, fostering the realisation of global-scale quantum networks. ...
The objectives of this research are twofold, first, to compare the performance of the qudit-based protocol with a similar qubit-based protocol, particularly in a satellite-based context, and second, to investigate the feasibility and potential advantages of employing high-dimensional qudit encoding for near-term long-range entanglement distribution. The theoretical framework encompasses various elements, including a single photon pair source, lossy transmission, mapping of qudit states to qubit memories, and heralding measurements.
Through various simulations, we evaluate the impact of different parameters on the performance of the proposed protocol. Our findings reveal that high-dimensional encoding significantly alleviates memory requirements, making it suitable for current technologies with low memory coherence times. Multiplexing techniques further enhance the achievable distances and transmission rates, highlighting their importance for realistic implementations. However, we note that higher-dimensional protocols introduce additional experimental challenges and errors, warranting further research and optimisation. Furthermore, we explore the effect of reducing dark count rates in detectors and analyse its influence on the overall performance. Our investigations underscore the need for substantial detector improvements, as current dark count probabilities are on the same order of magnitude as channel losses.
By advancing our understanding of satellite-based entanglement distribution using qudits, this research contributes to the development of practical and secure quantum communication networks. The results presented herein lay the groundwork for future advancements in quantum communication technologies, fostering the realisation of global-scale quantum networks. ...
The distribution of multiple entangled pairs plays a vital role in various applications, such as quantum metrology, blind quantum computing, quantum key distribution, and quantum teleportation. While qubit-based protocols exist, they are often limited by short coherence times in quantum memories and the need for individual pair generation, leading to inefficiencies and reduced fidelity. To address these challenges, this thesis focuses on the development and analysis of a comprehensive theoretical framework for satellite-based entanglement distribution using high-dimensional qudits. By employing high-dimensional qudit encoding, which enables the simultaneous entanglement of multiple pairs, we aim to enhance the capacity and efficiency of entanglement distribution schemes.
The objectives of this research are twofold, first, to compare the performance of the qudit-based protocol with a similar qubit-based protocol, particularly in a satellite-based context, and second, to investigate the feasibility and potential advantages of employing high-dimensional qudit encoding for near-term long-range entanglement distribution. The theoretical framework encompasses various elements, including a single photon pair source, lossy transmission, mapping of qudit states to qubit memories, and heralding measurements.
Through various simulations, we evaluate the impact of different parameters on the performance of the proposed protocol. Our findings reveal that high-dimensional encoding significantly alleviates memory requirements, making it suitable for current technologies with low memory coherence times. Multiplexing techniques further enhance the achievable distances and transmission rates, highlighting their importance for realistic implementations. However, we note that higher-dimensional protocols introduce additional experimental challenges and errors, warranting further research and optimisation. Furthermore, we explore the effect of reducing dark count rates in detectors and analyse its influence on the overall performance. Our investigations underscore the need for substantial detector improvements, as current dark count probabilities are on the same order of magnitude as channel losses.
By advancing our understanding of satellite-based entanglement distribution using qudits, this research contributes to the development of practical and secure quantum communication networks. The results presented herein lay the groundwork for future advancements in quantum communication technologies, fostering the realisation of global-scale quantum networks.
The objectives of this research are twofold, first, to compare the performance of the qudit-based protocol with a similar qubit-based protocol, particularly in a satellite-based context, and second, to investigate the feasibility and potential advantages of employing high-dimensional qudit encoding for near-term long-range entanglement distribution. The theoretical framework encompasses various elements, including a single photon pair source, lossy transmission, mapping of qudit states to qubit memories, and heralding measurements.
Through various simulations, we evaluate the impact of different parameters on the performance of the proposed protocol. Our findings reveal that high-dimensional encoding significantly alleviates memory requirements, making it suitable for current technologies with low memory coherence times. Multiplexing techniques further enhance the achievable distances and transmission rates, highlighting their importance for realistic implementations. However, we note that higher-dimensional protocols introduce additional experimental challenges and errors, warranting further research and optimisation. Furthermore, we explore the effect of reducing dark count rates in detectors and analyse its influence on the overall performance. Our investigations underscore the need for substantial detector improvements, as current dark count probabilities are on the same order of magnitude as channel losses.
By advancing our understanding of satellite-based entanglement distribution using qudits, this research contributes to the development of practical and secure quantum communication networks. The results presented herein lay the groundwork for future advancements in quantum communication technologies, fostering the realisation of global-scale quantum networks.