(QuTech) The quantum internet will be an infrastructure for reliably entangling and teleporting quantum bits (qubits) between remote nodes around the world. Not only will it offer fundamentally improved security compared to today’s internet, but it will also enable a range of game-changing applications. Remotely entangled qubits are for instance a key resource for doing distributed quantum computing, synchronising atomic clocks, and extending the baselines of telescopes. Thanks to recent scientific breakthroughs in entanglement generation, a quantum internet could be realised by the end of this decade if also the novel engineering challenge of scaling this technology can be overcome. To that end, the availability of capable modelling and simulation tooling to design and validate this new technology will be essential!
Designing a scalable quantum network stack
What are the key capabilities of such a simulation tool? Realising a quantum internet will require reinventing the complete network technology stack in terms of both hardware and software. Each layer of the stack must contend with the error-prone and short-lived lifetimes of physical qubits, which can probabilistically degrade or vanish while in transit or stored in memory. That means accurate physical modelling and time tracking are critical as well as the capability to efficiently deal with stochastic processes. Also important is the versatility to model a range of networkable quantum devices that rely on different physical principles, such as defect centres in diamond, ion traps, and atomic ensembles. Finally, to scale to large networks, the tool should be capable of classically simulating thousands of qubits, a priori a very resource intensive computational task.
NetSquid, a simulation platform for scalable quantum networks
At QuTech we addressed the need for a simulation platform capable of designing scalable quantum networks by developing NetSquid, the NETwork Simulator for QUantum Information using Discrete events. Its key innovation is to combine discrete event simulation, which is a modelling paradigm suited to network systems, with a specially developed toolkit for dynamic quantum computation. That allows NetSquid to accurately track quantum information over time across large and complex networks, and deal with the probabilistic feedback loops prevalent in quantum networking. Other notable features include a modular component library for versatile physical modelling, and a powerful asynchronous framework for programming network behaviour.
A design tool for engineers and scientists
Testbeds to demonstrate the building blocks of a quantum internet are being actively worked on around the world, bringing together research and development expertise from academia and industry. NetSquid aims to enable the engineers and scientists working in this domain to effectively design and validate every layer of the necessary quantum network stack. Use case examples of NetSquid include:
• Exploring the performance and requirements of quantum devices and their interconnections,
• Optimising quantum network architectures and network topologies,
• Designing and validating network protocols and control plane software,
• Studying end-user applications and their feasibility on non-ideal real-world hardware.
NetSquid was publicly released in June of 2020 and has a growing user base with 400 registered as of May 2021. Researchers at QuTech have already used NetSquid to develop the world’s first link layer protocol for a quantum network, and NetSquid is for instance used by the EU-funded Quantum Internet Alliance project to determine the requirements for building a pan-European quantum internet infrastructure.
Modular quantum computing architectures
Another promising domain for a design tool such as NetSquid is modular quantum computing. Quantum hardware platforms for quantum computing all have a limit in size beyond which they will need to be interconnected to scale further. These networked computing architectures share many of the same challenges of quantum networks in terms of communication applications, and thereby also the same modelling and simulation challenges that NetSquid has been developed to solve. We look forward to new collaborations for applying NetSquid to this exciting domain!
For more information about NetSquid see https://netsquid.org or contact Rob Knegjens (rob.knegjens[at]tno.nl).