Quantum Simulation and Emulation Techniques

Zenisha Devani, Zeel Kanudawala, Rohan Thakar +2 more

Miralem Mehić, Emir Dervisevic, Peppino Fazio +1 more

Network emulators are essential in testing network systems, applications, and protocols. Emulators bridge the gap between simulation setups that lack realism in results and real-world trials that are accurate but often expensive, non-reproducible, and uncontrollable. This paper describes the simulations and emulations of the national Czech QKD network. Using emulation techniques, a unique ecosystem is formed that includes the processes of generating, processing, storing, and consuming cryptographic keys. The presented tool will undoubtedly spur future development, understanding, and teaching, and it is critical for testing novel applications and protocols applied to QKD networks.

V. S. Anjusha, Swathi S. Hegde, T. S. Mahesh

Quantum simulators based on nuclear spin-systems controlled by NMR techniques have been used for studying various quantum phenomena. In this work, using a four-qubit NMR quantum simulator, we investigate the recently postulated quantum pigeon-hole effect. In mathematics, the pigeonhole effect is described by a set of three objects being allocated with only two containers. Classically, one would expect at least one container to accommodate more than one object. However, recently it was predicted that there exist quantum scenarios wherein three quantum particles appear to reside in two containers in such a way that no two particles can be simultaneously assigned with a single container. In our experiments, quantum pigeons are emulated by three nuclear qubits whose states are probed jointly and noninvasively by an ancillary spin. The qubit-states $\{\ket{0}$, $\ket{1}\}$ emulate the two containers available for each of the qubits. The experimental results are in good agreement with quantum theoretical predictions.

Anna Ouskova Leonteva, Guido Masella, Maxime Outteryck +2 more

Evaluating quantum algorithms at utility-scale—involving more than 100 qubits—is a key step toward advancing real-world applications of quantum computing. In this study, we benchmark seven state-of-the-art quantum emulators employing techniques such as tensor networks, matrix product states (MPS), decision diagrams, and factorized ket based methods, running on CPU based hardware and focusing on effectively exact simulations. Performance is assessed on 13 benchmark circuits from the MQTBench library, spanning circuit sizes from 4 to 1,024 qubits. Our results reveal that MPS-based emulators outperform other approaches overall, successfully solving 8 benchmarks up to the maximum size of 1,024 qubits and 12 benchmarks up to at least 100 qubits in less than 5 minutes. We find evidence that all circuits except a random one can be simulated in polynomial time. This work demonstrates that quantum emulators can faithfully simulate a broad range of large and complex universal quantum circuits with high fidelity, far beyond the limits of statevector simulators and today’s quantum hardware.

Brian Doolittle, Michael Cubeddu

Quantum networks are advancing the information technology infrastructure of society. Simulation and emulation software tools have emerged to support the design, development, and deployment of quantum networks, however, classical simulation and emulation methods have major bottlenecks in the error, latency, and cost that they can achieve at scale. In this work, we review quantum network simulation and emulation tools, including foundational principles, state-of-the-art tools, and bottlenecks. We then discuss how quantum technologies can address these challenges, and we construct a roadmap for the adoption of quantum simulation and emulation tools, emphasizing codesign with quantum network testbeds.