Emergent quantum technologies are opening up new horizons for researchers of different disciplines. One such promising technique is the teleportation of a quantum state. Theoretical physics and telecommunication are different fields for which quantum teleportation can be fruitful. Additionally, squeezed state of light is introduced in this paper as a tool for measurement accuracy improvement. Moreover, with the help of integrated Mach-Zehnder photonic cells and squeezed light source, we propose the use of a quantum photonic computation method (continuous variable quantum states) for the sake of quantum teleportation. We will further try to implement a quantum key distribution (QKD) algorithm based on this method and validate its feasibility as well.
Emergent quantum technologies are opening up new horizons for researchers of different disciplines. One such promising technique is the teleportation of a quantum state. Theoretical physics and telecommunication are different fields for which quantum teleportation can be fruitful. Additionally, squeezed state of light is introduced in this paper as a tool for measurement accuracy improvement. Moreover, with the help of integrated Mach-Zehnder photonic cells and squeezed light source, we propose the use of a quantum photonic computation method (continuous variable quantum states) for the sake of quantum teleportation. We will further try to implement a quantum key distribution (QKD) algorithm based on this method and validate its feasibility as well.
We investigate experiments of continuous-variable quantum information processing based on the teleportation scheme. Quantum teleportation, which is realized by a two-mode squeezed vacuum state and measurement-and-feedforward, is considered as an elementary quantum circuit as well as quantum communication. By modifying ancilla states or measurement-and-feedforwards, we can realize various quantum circuits which suffice for universal quantum computation. In order to realize the teleportation-based computation we improve the level of squeezing, and fidelity of teleportation. With a high-fidelity teleporter we demonstrate some advanced teleportation experiments, i.e., teleportation of a squeezed state and sequential teleportation of a coherent state. Moreover, as an example of the teleportation-based computation, we build a QND interaction gate which is a continuous-variable analog of a CNOT gate. A QND interaction gate is constructed only with ancillary squeezed vacuum states and measurement-and-feedforwards. We also create continuous-variable four mode cluster type entanglement for further application, namely, one-way quantum computation.
Abstract In the field of quantum information, quantum teleportation, as a highly promising core technology, has attracted widespread attention from researchers worldwide. Quantum entanglement, a special correlation between two or more quantum systems, provides indispensable theoretical support for quantum teleportation. However, current research on quantum teleportation still faces several key challenges, including the preparation of efficient and stable entanglement sources, the high-fidelity maintenance of entangled states, and compatibility with practical communication systems. Microcavity entanglement sources, as a crucial element in quantum teleportation research, are a core component of cavity quantum electrodynamics (Cavity QED) schemes, and their performance directly affects the efficiency and reliability of the entire teleportation system. Addressing these challenges, this paper proposes a quantum teleportation scheme based on a silicon nitride microring resonator as the entanglement source. The feasibility of the scheme is analyzed theoretically and verified via numerical simulation. This scheme utilizes four-wave mixing technology to directly generate high-fidelity polarization-entangled photon pairs in the microcavity. This not only achieves miniaturization and integration of the entanglement source but also significantly improves entanglement generation efficiency through optimized microcavity design, providing a practical solution to overcome the numerical bottlenecks currently faced in quantum teleportation. Using this entanglement source as a quantum channel, a continuous-variable quantum teleportation protocol is designed: Alice performs a Bell state measurement on the unknown input state and the local entangled mode using homodyne detection, while Bob reconstructs the quantum state based on the classical communication results through conditional displacement. This research theoretically establishes the feasibility of microcavity entanglement sources for high-fidelity quantum teleportation, with numerical simulations confirming the predicted performance.
Abstract Quantum key distribution (QKD) represents a cornerstone of secure communication in the quantum era. While discrete-variable QKD (DV-QKD) protocols were historically the first to demonstrate secure key exchange, continuous-variable QKD (CV-QKD) has emerged as a more practical alternative due to its seamless compatibility with current telecommunications infrastructure. CV-QKD relies on coherent and squeezed states of light, offering significant advantages for integration into modern optical networks. This review comprehensively explores the theoretical underpinnings, technological advancements, and practical challenges of CV-QKD. Special attention is given to the role of photonic integrated circuits (PICs) in enabling scalable and efficient implementation of CV-QKD systems. Furthermore, recent advances in machine learning have been leveraged to optimize CV-QKD performance, with data-driven techniques enhancing noise estimation, parameter optimization, and system security. Additionally, tensor networks provide efficient computational tools for analyzing complex quantum correlations, improving the efficiency and robustness of quantum key distribution protocols. These developments, combined with ongoing improvements in quantum photonic integration, pave the way for the practical deployment of large-scale, high-speed quantum-secure networks.
Quantum teleportation is a building block in quantum computation and quantum communication. The continuous-variable polarization squeezed state is a key resource in quantum networks, offering advantages for long-distance distribution and direct interfacing of quantum nodes. Although polarization squeezed state has been generated and distributed between remote users, it is a long-standing goal to implement controlled quantum teleportation of the polarization squeezed state with multiple remote users. Here, we propose a feasible scheme to teleport a polarization squeezed state among multiple remote users under control. The polarization state is transferred between different remote quantum networks, and the controlled quantum teleportation of the polarization state can be implemented in one quantum network involving multiple remote users. The results show that such a controlled quantum teleportation can be realized with 36 users through about 6-km free-space or fiber quantum channels, where the fidelity of 0.352 is achieved beyond the classical limit of 0.349 with an input squeezing variance of 0.25. This scheme provides a direct reference for the experimental implementation of remote and controlled quantum teleportation of polarization states, thus enabling more teleportation-based quantum network protocols.
Quantum key distribution (QKD), guaranteed by the principles of quantum mechanics, is one of the most promising solutions for the future of secure communication. Integrated quantum photonics provides a stable, compact, and robust platform for the implementation of complex photonic circuits amenable to mass manufacture, and also allows for the generation, detection, and processing of quantum states of light at a growing system's scale, functionality, and complexity. Integrated quantum photonics provides a compelling technology for the integration of QKD systems. In this review, we summarize the advances in integrated QKD systems, including integrated photon sources, detectors, and encoding and decoding components for QKD implements. Complete demonstrations of various QKD schemes based on integrated photonic chips are also discussed.
Generation of ``squeezed'' light is a key technology for quantum information processing with continuous variables. In this field, continuous-variable quantum sampling is a promising candidate for near-term demonstration of quantum advantage. Despite many years of progress, though, a squeezed-light source suitable for quantum sampling has not been demonstrated. This work finally provides a blueprint for squeezed-light sources that can be used for large-scale quantum sampling applications, and thus will have an impact on advancing photonic quantum technology for practical deployment.