Currently under development at QuTech, NetSquid is the world’s first network simulator that is capable of simulating the decay of quantum information over time together with noisy operations and stochastic feedback loops. Its primary use is the prediction of the performance of quantum network protocols in a physically-realistic setting.

NetSquid’s features include:

  • discrete event simulator to simulate delays in transmission, storage, and computation
  • Extendable libraries of network components and protocols, with a user contributed snippet database.
  • Multiple quantum state formalisms, with trade offs that include versatility, speed, and memory efficiency.
  • Available as a Python 3 package, using Numpy/SciPy, Cython, and C++ under the hood.

Use cases

Simulating long quantum repeater chains

A necessary requirement for quantum internet applications is the capability to generate long-distance entanglement. Unfortunately, the entanglement-generation rate decays exponentially with distance for photons travelling through fibre. This problem can be overcome by a chain of quantum repeater nodes, whose end nodes become entangled through teleporting an entangled state through the chain. We use NetSquid to simulate long quantum repeater chains where the nodes use NV-center technology. In particular, we investigate the influence of several hardware parameters such as readout fidelity and memory decay time on the fidelity and generation time of the final end-to-end entangled state.

— Tim Coopmans (QuTech)

Simulating a link layer protocol for quantum networks

An Entanglement Generation Protocol (EGP) in the link layer of a quantum internet has the task of generating entanglement between nodes which are directly connected through some medium, possibly including a heralding station in between. Additionally to communicating with the physical layer such that correct operations are applied for entanglement generation, the EGP will perform simple scheduling of entanglement generation requests and provide necessary information to higher layers such that the nodes can agree on a total ordering of the entangled pairs without having to communicate. We use NetSquid to simulate the performance of our proposed EGP, using metrics such as latency, fidelity, throughput, fairness etc, in the presence of noise and timing delays. Furthermore, we investigate the robustness of the protocol under realistic and exaggerated noise on the classical control messages. See our paper on a quantum link layer.

— Axel Dahlberg (QuTech)