AffiliationUniversity of Arizona, Department of Electrical and Computer Engineering
Entanglement-based hybrid QKD
Hybrid CV-DV entangled states
Hybrid power systems
Hybrid quantum communication networks
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CitationDjordjevic, I. B. (2022). Hybrid CV-DV Quantum Communications and Quantum Networks. IEEE Access.
RightsCopyright © 2022 IEEE. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
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AbstractQuantum information processing (QIP) opens new opportunities for high-performance computing, high-precision sensing, and secure communications. Among various QIP features, the entanglement is a unique one. To take full advantage of quantum resources, it will be necessary to interface quantum systems based on different encodings of information both discrete and continuous. The goal of this paper is to lay the groundwork for the development of a robust and efficient hybrid continuous variable-discrete variable (CV-DV) quantum network, enabling the distribution of a large number of entangled states over hybrid DV-CV multi-hop nodes in an arbitrary topology. The proposed hybrid quantum communication network (QCN) can serve as the backbone for a future quantum Internet, thus providing extensive long-term impacts on the economy and national security through QIP, distributed quantum computing, quantum networking, and distributed quantum sensing. By employing the photon addition and photon subtraction modules we describe how to generate the hybrid DV-CV entangled states and how to implement their teleportation and entanglement swapping through entangling measurements. We then describe how to extend the transmission distance between nodes in hybrid QCN by employing macroscopic light states, noiseless amplification, and reconfigurable quantum LDPC coding. We further describe how to enable quantum networking and distributed quantum computing by employing the deterministic cluster state concept introduced here. Finally, we describe how the proposed hybrid CV-DV states can be used in an entanglement-based hybrid QKD. Author
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Except where otherwise noted, this item's license is described as Copyright © 2022 IEEE. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
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Hybrid Entanglement Distribution between Remote Microwave Quantum Computers Empowered by Machine LearningZhang, B.; Wu, J.; Fan, L.; Zhuang, Q.; Department of Physics, University of Arizona; Department of Electrical and Computer Engineering, University of Arizona; James C. Wyant College of Optical Sciences, University of Arizona (American Physical Society, 2022-12-06)Superconducting microwave circuits with Josephson junctions, the major platform for quantum computing, can only reach the full capability when connected. This requires an efficient protocol to distribute microwave entanglement. While quantum computers typically use discrete-variable (DV) methods for information encoding, the entire continuous-variable (CV) degree of freedom in electromagnetic fields must be utilized to achieve the highest entanglement distribution rate. Here, we propose a hybrid protocol to resolve the incompatibility between DV microwave quantum computers and CV quantum communications. CV microwave entanglement is distributed using optical swapping of optical-microwave entanglement pairs. To interface with DV microwave quantum computers, we further design a hybrid circuit to simultaneously convert and distill high-quality DV entanglement from noisy CV entanglement. The hybrid circuit is trained with machine-learning algorithms, ensuring high entanglement fidelity and generation rate. Our work not only provides a practical method to realize efficient quantum links for superconducting microwave quantum computers, but also opens avenues to bridge the gap between DV and CV quantum systems. © 2022 American Physical Society.
Trapped Ion Quantum Repeaters with Entanglement Distillation based on Quantum LDPC CodesKang, Ann; Guha, Saikat; Rengaswamy, Narayanan; Seshadreesan, Kaushik P.; College of Optical Sciences, University of Arizona; College of Engineering, University of Arizona (IEEE, 2023-09-17)Quantum repeaters are essential to realizing long-range entanglement distribution networks. To achieve enhanced rates of high-fidelity entanglement distribution, we investigate how entanglement distillation can be used on trapped-ion-based quantum repeater networks. Entanglement distillation is the process of distilling from a large number of copies of low-fidelity entangled qubits a fewer number of copies of higher-fidelity entangled qubits. It has been shown that quantum error-correcting codes (QECCs) can be used to devise protocols for entanglement distillation. In this paper, we consider entanglement distillation based on three lifted-product (LP) quantum low density parity check (QLPDC) codes ([[544, 80, 12], [[714, 100, 16]], and [20, 10, 136, 20]) on trapped-ion repeater networks with spatial and time multiplexing over various total distances with different inter-repeater spacing to calculate the end-to-end entanglement rates that they enable. The reported rates assume entanglement over each elementary link succeeds synchronously and do not assume any constraint on the number of ions present in each trap. We furthermore assume that distillation occurs at every elementary link and that the entanglement swaps are ideal. Our findings can be considered as groundwork for implementing more efficient distillation and communication protocols on trapped ion networks.
Entangled quantum systems meaningfully encode information: A formal demonstration.Garcia, J. D.; Trujillo, Logan Thomas (The University of Arizona., 2005)"Quantum information" refers to the information-theoretic properties of quantum systems. There is still a general prejudice among physicists against the idea that these systems express information due to the nonlocal behavior of entangled quantum systems. The present paper calculates the information content of simple two-state entangled systems (anti-aligned spin-1/2 electron-positron pair, anti-polarized spin-1 photon pair). This calculation involves a modified application of the entropy formalism of quantum statistical mechanics. In addition, the classical and quantum analogues of mutual information are calculated for the entangled particles and experimental devices used to measure them. It is shown that the amount of information expressed by the spin measurement devices depends upon their parameter settings; the spin information of an entangled system prior to measurement is a constant. These results indicate a distinction between information available to a system's sub-components versus that available to measurement devices outside the system. This "inaccessible" information is likely carried by other physical properties of the system.