A detailed analysis of the performance and required resources for an all-photonic quantum repeater architecture is presented. It is shown how to significantly outperform the bit rate achievable by any repeaterless direct-transmission protocol despite various device losses, and also dramatically decrease the number of required photon sources.
A detailed analysis of the performance and required resources for an all-photonic quantum repeater architecture is presented. It is shown how to significantly outperform the bit rate achievable by any repeaterless direct-transmission protocol despite various device losses, and also dramatically decrease the number of required photon sources.
We present a resource-performance tradeoff of an all-optical quantum repeater that uses photon sources, linear optics, photon detectors, and classical feedforward at each repeater node, but no quantum memories. We show that the quantum-secure key rate has the form R(eta) = D eta(s) bits per mode, where I) is the end-to-end channel's transmissivity, and the constants D and s are functions of various device inefficiencies and the resource constraint, such as the number of available photon sources at each repeater node. Even with lossy devices, we show that it is possible to attain s < 1, and in turn outperform the maximum key rate attainable without quantum repeaters, R-direct(eta) = log2(1-eta)approximate to(1/ln 2)eta bits per mode for eta << 1, beyond a certain total range L, where eta similar to e(-alpha L) in optical fiber. We also propose a suite of modifications to a recently proposed all-optical repeater protocol that ours builds upon, which lower the number of photon sources required to create photonic clusters at the repeaters so as to outperform R-direct(eta), from similar to 10(11) to similar to 10(6) photon sources per repeater node. We show that the optimum separation between repeater nodes is independent of the total range L and is around 1.5 km for assumptions we make on various device losses.
Quantum communication technologies show great promise for applications ranging from the secure transmission of secret messages to distributed quantum computing. Due to fiber losses, long-distance quantum communication requires the use of quantum repeaters, for which there exist quantum memory-based schemes and all-photonic schemes. While all-photonic approaches based on graph states generated from linear optics avoid coherence time issues associated with memories, they outperform repeater-less protocols only at the expense of a prohibitively large overhead in resources. Here, we consider using matter qubits to produce the photonic graph states and analyze in detail the trade-off between resources and performance, as characterized by the achievable secret key rate per matter qubit. We show that fast two-qubit entangling gates between matter qubits and high photon collection and detection efficiencies are the main ingredients needed for the all-photonic protocol to outperform both repeater-less and memory-based schemes.
Entangled photons can be used to create a truly secure communication link between two parties. However, the distance over which this can be achieved is limited by the transmission losses associated with optical fibers. One potential solution is using quantum repeaters (QRs) where initial entanglement is created over short distances and then extended via entanglement swapping. The system-level performance metrics (data rate, fidelity of entanglement, etc.) impose demands upon the hardware components (of a QR), which can be used to guide applied materials and device design toward these objectives. This has become increasingly important with an expanding list of candidates for quantum technologies, as the physical realization of each qubit or detector technology brings its own set of advantages and disadvantages. In this article, we present a framework that uses a modular QR and highlights the tradeoffs that exist between technological component modules. Using reported values, we take a near-term perspective and show the achievable range of rates as a function of distance and the corresponding requirements on matter qubit properties.
The field of quantum communications promises the faithful distribution of quantum information, quantum entanglement, and absolutely secret keys. However, the highest rates of these tasks are fundamentally limited by the transmission distances. Quantum repeaters are necessary to overcome the repeaterless bound which sets the fundamental rate-distance limit of any repeaterless quantum communication protocol. The ultimate end-to-end rates of quantum repeater networks are known to be achievable by an optimal entanglement-distillation protocol followed by quantum teleportation. In this thesis, we give physical repeater designs for this achievability. We also propose practical repeater designs with near-term potential for real-world practical applications.
Developing and deploying advanced Quantum Repeater (QR) technologies will be necessary to scale quantum networks at longer distances. Depending on the error mitigation mechanisms adopted to suppress loss and errors, QRs are typically classified into “memory-based” or “all-photonic” QRs, and each type of QR may be best suited for a specific type of underlying quantum technology, a particular scale of quantum network, or a specific regime of operational parameters. Modeling and simulation of quantum repeaters and networks can help in understanding the relative performance and resource requirements of different types of QRs, identify tradeoffs of alternative quantum network architectures, optimize quantum hardware, and assist in the design of a robust control plane. This paper introduces a quantum repeater simulation toolkit based on NetSquid, which includes component models and protocols to study advanced quantum repeater networks. We present our initial research findings on modeling and simulation of “allphotonic” entanglement-based QRs and “memory-based” first generation trapped ion QRs. We study the relative performance and resource requirements of these two different types of QRs and networks. The performance metrics include entanglement generation rate and fidelity between the endpoints of the network. For fair comparison of resource requirements of different types of QRs, entanglement generation rate is normalized by the total number of matter qubits involved.
Developing and deploying advanced Quantum Repeater (QR) technologies will be necessary to scale quantum networks to longer distances. Depending on the error mitigation mechanisms adopted to suppress loss and errors, QRs are typically classified into memory-based or all-photonic QRs; and each type of QR may be best suited for a specific type of underlying quantum technology, a particular scale of quantum networks, or a specific regime of operational parameters. We perform theoretical analysis and simulations of quantum repeaters and networks to investigate the relative performance and resource requirements of different quantum network paradigms. Our results will help guide the optimization of quantum hardware and components and shed light on the role of a robust control plane. We present our research findings on theoretical analysis and simulations of memory-based first-generation trapped-ion quantum repeaters and networks, and all-photonic entanglement-based quantum repeaters and networks. We study the relative performance in terms of entanglement generation rate and fidelity, as well as the resource requirements of these two different quantum network paradigms.