International Conference on Transparent Optical Networks
Scalable Quantum Signal Processing with Integrated Photonics and Fiber-based Modules
Nicola Montaut, Piotr Roztocki, Hao Yu, Stefania Sciara, Mario Chemnitz, Y. Jestin, Benjamin MacLellan, Bennet Fischer, Michael Kues, Christian Reimer, Luis Romero Cortés, Benjamin Wetzel, Yanbing Young Zhang, Sébastien Loranger, Raman Kashyap, Alfonso Carmelo Cino, Sai T. Chu, Brent E. Little, David Moss, Lucia Caspani, William J. Munro, José Azaña, Roberto Morandotti
Quantum photonic resources are critical for advanced applications such as quantum computation, communication, and information processing. Efficient generation and detection of quantum states, as well as reliable photon manipulation techniques, are essential for the development of practical quantum technologies. Integrated photonic platforms offer attractive solutions due to their stability, small device footprint, and improved power efficiencies. However, optical loss and environmental noise hinder their capability to transmit, measure, and detect quantum states with high accuracies. To tackle these limitations, we have developed robust solutions for quantum signal processing by leveraging infrastructures from telecommunications and integrated photonics. These approaches focus on the use of silicon-based photonic sources for entanglement generation in the time and frequency degrees of freedom, as well as chip- and fiber-based architectures for entanglement verification via quantum interference and tomography measurements. Our photonic schemes allow for high-dimensional entanglement processing, demonstrating their versatility in developing scalable and cost-efficient quantum signal processing platforms.
Quantum photonic resources are critical for advanced applications such as quantum computation, communication, and information processing. Efficient generation and detection of quantum states, as well as reliable photon manipulation techniques, are essential for the development of practical quantum technologies. Integrated photonic platforms offer attractive solutions due to their stability, small device footprint, and improved power efficiencies. However, optical loss and environmental noise hinder their capability to transmit, measure, and detect quantum states with high accuracies. To tackle these limitations, we have developed robust solutions for quantum signal processing by leveraging infrastructures from telecommunications and integrated photonics. These approaches focus on the use of silicon-based photonic sources for entanglement generation in the time and frequency degrees of freedom, as well as chip- and fiber-based architectures for entanglement verification via quantum interference and tomography measurements. Our photonic schemes allow for high-dimensional entanglement processing, demonstrating their versatility in developing scalable and cost-efficient quantum signal processing platforms.
Quantum technologies harness nonclassical features of particles, here, photons, to develop novel, efficient, and precise devices for information processing applications. Superposition, entanglement, as well as the coherent manipulation of quantum states are at the heart of the second quantum revolution (quantum 2.0) which targets the development of secure cryptographic systems, complex computation protocols, and more. Emerging quantum architectures rely on the realistic implementation of photonic schemes which are scalable, resource-efficient, and compatible with CMOS technologies as well as fiber networks. This work demonstrates current schemes utilized for time-/frequency-bin entanglement generation and processing by leveraging existing telecommunications and integrated photonics infrastructures.
The development of integrated photonic systems, both on-chip and fiber-based, has transformed quantum photonics by replacing bulky, fragile free-space optical setups with compact, efficient, and robust circuits. Photonic platforms incorporating fiber-connected sources of correlated and entangled photon pairs offer practical advantages, such as operation at room temperature, efficient integration with telecom infrastructure, and compatibility with mature and efficient semiconductor fabrication processes for cost-effective and large-scale optical circuits. The stability and scalability of integrated quantum photonics platforms have facilitated the generation and processing of quantum information in the temporal domain within a single spatial mode. Time-bin encoded states, known for their robustness against decoherence and compatibility with existing fiber-optic infrastructure, have shown to be an efficient paradigm for advanced applications like quantum secure communication, information processing, spectroscopy, imaging, and sensing. This review examines recent advancements in fiber- and chip-based platforms for generating non-classical states and their applications as quantum state processors in the time domain. We discuss the generation of pulsed quantum frequency combs using microring resonators and intra-cavity mode-locked laser schemes, enabling co- and cross-polarized quantum photonic states. Additionally, the versatility of these resonator chips for entanglement generation is emphasized, including two- and multi-photon time-bin entangled schemes. We highlight the development of time-bin entanglement analyzers in fiber architectures, featuring ultrahigh stability and post-selection-free capabilities, which enable precise and efficient characterization of two- and higher-dimensional time-bin entanglement. We also review scalable on-chip schemes for quantum key distribution, demonstrating low quantum bit error rates and compatibility with higher-dimensional quantum communication protocols. Further, methods for enhancing temporal resolution in detection schemes, crucial for time-bin encoding, are presented, such as the time-stretch sampling technique using electro-optic modulation. These innovations, relying on readily available, telecom-based fiber-optic components, provide practical, scalable, and cost-effective solutions for advancing quantum photonic technologies. Looking forward, time-bin encoding is expected to play a pivotal role in the advancement of quantum repeaters, distributed quantum networks, and hybrid light-matter systems, advancing the realization of globally scalable quantum technologies.
Silicon quantum photonics is a promising platform for the development of advanced quantum information technologies, offering a high level of stability, controllability, scalability and integration density. Silicon quantum photonics has enabled a range of key demonstrations including the development of a versatile toolbox for controlling single-photon’s different degrees of freedom, the generation of multipartite entanglement and high-dimensional entanglement, and realization of large-scale programmable quantum devices. The progress has unlocked the unprecedented power of chip-scale quantum photonic technologies for advanced applications in quantum communication, computing and simulation.
Abstract High-dimensional quantum entanglement is an important resource for emerging quantum technologies such as quantum communication and quantum computation. The scalability of metres-long experimental setups limits high-dimensional entanglement in bulk optics. Advancements in quantum technology hinge on reproducible, and reconfigurable quantum devices—including photon sources, which are challenging to achieve in a scalable manner using bulk optics. Advances in nanotechnology and CMOS-compatible integration techniques have enabled the generation of entangled photons on millimeter-scale chips, significantly enhancing scalability, stability, replicability, and miniaturization for real-world quantum applications. In recent years we have seen several chip-scale demonstrations with different discrete degrees of freedom including path, frequency-bin, time-bin, and transverse modes, on many material platforms. A complete quantum photonic integrated circuit requires the generation, manipulation, and detection of quantum states, involving various active and passive quantum photonic components which further increase the degree of complexity. Here, we focus on the high-dimensional versions of qubits—qudits—and review the nonlinear optical processes that facilitate on-chip high-dimensional entangled photon sources, and the currently used material platforms. We discuss a range of current implementations of on-chip high-dimensional entangled photon sources and demonstrated applications. We comment on the current challenges due to the limitations of individual material platforms and present future opportunities in hybrid and heterogeneous integration strategies for the next generation of integrated quantum photonic chips.
Photonic quantum technologies that harness the fundamental laws of quantum physics open the possibility of developing quantum computing and communication that could show unprecedented computational power on specific problems and unconditional information security, respectively. However, the lack of high-efficiency single-photon sources and integrated photonic circuits that can generate, manipulate and analyse entanglement states are the major hurdles to demonstrate the quantum advantages. The potential solutions are clearly explained in this thesis. Chapter 1 provides a brief overview that explains the theme of each chapter. Chapter 2 emphasises the importance of a high-efficiency single-photon source and an integrated time-bin entanglement chip, after explaining the advantages of photonic quantum computing and communication over their classical counterparts. In Chapter 3, three different temporal multiplexing schemes are experimentally demonstrated as the potential solutions to build a high-efficiency single-photon source. Chapter 3 also identifies the potential limitations of temporal multiplexing with high repetition rate. In Chapter 4, the linear processing circuits and nonlinear photon source are separately demonstrated in a low-loss double-stripe silicon nitride waveguide. In the final section of Chapter 4, an integrated silicon nitride time-bin entanglement chip that combines linear processing circuits and nonlinear photon sources is demonstrated as a potential solution to build a robust, scalable and cost-efficient quantum network in the real world. After a succinct summarisation, the final chapter briefly discusses the promising strategies and platforms to build an integrated high-efficiency single-photon source and an integrated quantum node with broad bandwidth and long storage time.