scholarly journals Effective routing design for remote entanglement generation on quantum networks

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Changhao Li ◽  
Tianyi Li ◽  
Yi-Xiang Liu ◽  
Paola Cappellaro
Keyword(s):  
Scheduling Algorithm ◽  
Capacity Allocation ◽  
Quantum Network ◽  
Multiple Perspectives ◽  
Entanglement Purification ◽  
Quantum Networks ◽  
Entanglement Generation ◽  
The Road ◽  
Routing Scheme ◽  
Lattice Network

AbstractQuantum network is a promising platform for many ground-breaking applications that lie beyond the capability of its classical counterparts. Efficient entanglement generation on quantum networks with relatively limited resources such as quantum memories is essential to fully realize the network’s capabilities, the solution to which calls for delicate network design and is currently at the primitive stage. In this study we propose an effective routing scheme to enable automatic responses for multiple requests of entanglement generation between source-terminal stations on a quantum lattice network with finite edge capacities. Multiple connection paths are exploited for each connection request while entanglement fidelity is ensured for each path by performing entanglement purification. The routing scheme is highly modularized with a flexible nature, embedding quantum operations within the algorithmic workflow, whose performance is evaluated from multiple perspectives. In particular, three algorithms are proposed and compared for the scheduling of capacity allocation on the edges of quantum network. Embodying the ideas of proportional share and progressive filling that have been well-studied in classical routing problems, we design another scheduling algorithm, the propagatory update method, which in certain aspects overrides the two algorithms based on classical heuristics in scheduling performances. The general solution scheme paves the road for effective design of efficient routing and flow control protocols on applicational quantum networks.

THE PARITY GATE: FROM QUANTUM NETWORKS TO ENTANGLEMENT GENERATION

2007 ◽  
Vol 05 (01n02) ◽  
pp. 3-7 ◽  
Author(s):  
RADU IONICIOIU
Keyword(s):  
Quantum Computing ◽  
Network Model ◽  
Quantum Network ◽  
Quantum Networks ◽  
Entanglement Generation ◽  
Simple Quantum ◽  
Parity Gate ◽  
Linear Elements ◽  
Quantum Network Model ◽  
Parity Measurement

It has been shown recently that parity measurement is an efficient entangler for fermions and hence is a universal resource for fermionic quantum computing with linear elements. In this article, we investigate several properties of the parity P-gate. We construct a simple quantum network model for the P-gate and derive gate identities for it. Finally, we examine entanglement generation using parity measurements.

scholarly journals Threshold Determination for Sharing Bus Rapid Transit–Exclusive Lanes with Conventional Buses

2019 ◽  
Vol 11 (17) ◽  
pp. 4592
Author(s):  
Yue ◽  
Chen ◽  
Yang ◽  
Ye
Keyword(s):  
Influencing Factors ◽  
Operation Time ◽  
Analytical Models ◽  
Bus Rapid Transit ◽  
Utilization Rate ◽  
Rapid Transit ◽  
Multiple Perspectives ◽  
The Road ◽  
Road Section ◽  
Stop Spacing

Sharing bus rapid transit (BRT) exclusive lanes with conventional buses is being considered to solve the problem of low utilization rate of BRT-exclusive lanes. However, the quantitative conditions and threshold that determine when to share need to be study. This paper took the common section of BRT and conventional bus lines as its research object. Practical investigation was conducted to analyze shared characteristics from multiple perspectives and explore influencing factors and mechanisms for sharing implementation. Based on the survey results, analytical models were established to quantify the influencing factors from three perspectives of road section, intersection, and bus stop. We selected departure volume of conventional buses as a threshold index and then summarized the constraints and the calculation process of sharing threshold. Finally, numerical examples of different scenarios were used to verify the feasibility and effectiveness of the method. The operation efficiency of the road section on exclusive lanes was the constraint on the lower limit of the shared threshold, while the upper limit was constrained by queuing probability or bus operation time under different intersections and stop spacing, which can provide reference for the shared setting of exclusive bus lanes.

Towards quantum networks of single spins: analysis of a quantum memory with an optical interface in diamond

2015 ◽  
Vol 184 ◽  
pp. 173-182 ◽  
Author(s):  
M. S. Blok ◽  
N. Kalb ◽  
A. Reiserer ◽  
T. H. Taminiau ◽  
R. Hanson
Keyword(s):  
Quantum Information Processing ◽  
Quantum States ◽  
Nitrogen Vacancy ◽  
Nuclear Spins ◽  
Quantum Repeater ◽  
Quantum Networks ◽  
Entanglement Generation ◽  
Quantum Bit ◽  
Single Defect ◽  
Coupling Parameters

Single defect centers in diamond have emerged as a powerful platform for quantum optics experiments and quantum information processing tasks. Connecting spatially separated nodes via optical photons into a quantum network will enable distributed quantum computing and long-range quantum communication. Initial experiments on trapped atoms and ions as well as defects in diamond have demonstrated entanglement between two nodes over several meters. To realize multi-node networks, additional quantum bit systems that store quantum states while new entanglement links are established are highly desirable. Such memories allow for entanglement distillation, purification and quantum repeater protocols that extend the size, speed and distance of the network. However, to be effective, the memory must be robust against the entanglement generation protocol, which typically must be repeated many times. Here we evaluate the prospects of using carbon nuclear spins in diamond as quantum memories that are compatible with quantum networks based on single nitrogen vacancy (NV) defects in diamond. We present a theoretical framework to describe the dephasing of the nuclear spins under repeated generation of NV spin-photon entanglement and show that quantum states can be stored during hundreds of repetitions using typical experimental coupling parameters. This result demonstrates that nuclear spins with weak hyperfine couplings are promising quantum memories for quantum networks.

scholarly journals Graph Picture of Linear Quantum Networks and Entanglement

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 611
Author(s):  
Seungbeom Chin ◽  
Yong-Su Kim ◽  
Sangmin Lee
Keyword(s):  
Perfect Matching ◽  
Entangled States ◽  
Entangled State ◽  
Quantum Networks ◽  
Entanglement Generation ◽  
Essential Information ◽  
Quantum Particles ◽  
Number Increase ◽  
Mapping Process ◽  
Linear Quantum

The indistinguishability of quantum particles is widely used as a resource for the generation of entanglement. Linear quantum networks (LQNs), in which identical particles linearly evolve to arrive at multimode detectors, exploit the indistinguishability to generate various multipartite entangled states by the proper control of transformation operators. However, it is challenging to devise a suitable LQN that carries a specific entangled state or compute the possible entangled state in a given LQN as the particle and mode number increase. This research presents a mapping process of arbitrary LQNs to graphs, which provides a powerful tool for analyzing and designing LQNs to generate multipartite entanglement. We also introduce the perfect matching diagram (PM diagram), which is a refined directed graph that includes all the essential information on the entanglement generation by an LQN. The PM diagram furnishes rigorous criteria for the entanglement of an LQN and solid guidelines for designing suitable LQNs for the genuine entanglement. Based on the structure of PM diagrams, we compose LQNs for fundamental N-partite genuinely entangled states.

scholarly journals Policies for elementary links in a quantum network

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 537
Author(s):  
Sumeet Khatri
Keyword(s):  
Decision Process ◽  
Success Probability ◽  
Coherence Time ◽  
Decision Processes ◽  
Quantum Network ◽  
Quantum Networks ◽  
Fundamental Limitations ◽  
Process Framework ◽  
Entanglement Distribution ◽  
Near Term

Distributing entanglement over long distances is one of the central tasks in quantum networks. An important problem, especially for near-term quantum networks, is to develop optimal entanglement distribution protocols that take into account the limitations of current and near-term hardware, such as quantum memories with limited coherence time. We address this problem by initiating the study of quantum network protocols for entanglement distribution using the theory of decision processes, such that optimal protocols (referred to as policies in the context of decision processes) can be found using dynamic programming or reinforcement learning algorithms. As a first step, in this work we focus exclusively on the elementary link level. We start by defining a quantum decision process for elementary links, along with figures of merit for evaluating policies. We then provide two algorithms for determining policies, one of which we prove to be optimal (with respect to fidelity and success probability) among all policies. Then we show that the previously-studied memory-cutoff protocol can be phrased as a policy within our decision process framework, allowing us to obtain several new fundamental results about it. The conceptual developments and results of this work pave the way for the systematic study of the fundamental limitations of near-term quantum networks, and the requirements for physically realizing them.

Distributed Coherent Absorption in Quantum Networks for Deterministic Entanglement Generation

2021 ◽  
Author(s):  
Anton N. Vetlugin ◽  
Ruixiang Guo ◽  
Cesare Soci ◽  
Nikolay I. Zheludev
Keyword(s):  
Quantum Networks ◽  
Entanglement Generation
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