QuantumACES.jl: design noise characterisation experiments for quantum computers

Daniele Cuomo

Daniel O’Malley, Velimir V. Vesselinov

Quantum computers are becoming more widely available, so it is important to develop tools that enable people to easily program these computers to solve complex problems. To address this issue, we present the design and two applications of ToQ.jl, a high-level programming language for D-Wave quantum annealing machines. ToQ.jl leverages the metaprogramming facilities in Julia (a high-level, high-performance programming language for technical computing) and uses D-Wave's ToQ programming language as an intermediate representation. This makes it possible for a programmer to leverage all the capabilities of Julia, and the D-Wave machine is used as a co-processor. We demonstrate ToQ.jl via two applications: (1) a pedagogical example based on a map-coloring problem and (2) a linear least squares problem. We also discuss our experience using ToQ.jl with a D-Wave 2X, particularly with respect to a linear least squares problem which is of broad interest to the scientific computing community.

Thomas Grurl, Jürgen Fuß, Robert Wille

Huai-Ming Yu, Jing Liu

As the main theoretical support of quantum metrology, quantum parameter estimation must follow the steps of quantum metrology towards the applied science and industry. Hence, optimal scheme design will soon be a crucial and core task for quantum parameter estimation. To efficiently accomplish this task, software packages aimed at computer-aided design are in high demand. In response to this need, we hereby introduce QuanEstimation.jl, an open-source Julia framework for scheme evaluation and design in quantum parameter estimation. It can be used either as an independent package or as the computational core of the recently developed hybrid-language (Python-Julia) package QuanEstimation [Phys. Rev. Res. 4 (4) (2022) 043057]. Utilizing this framework, the scheme evaluation and design in quantum parameter estimation can be readily performed, especially when quantum noises exist.

Evan T. Hockings

Noise is the fundamental challenge to quantum computation. Large-scale quantum computers will overcome this challenge with fault-tolerant architectures that leverage quantum error correction. This thesis introduces and investigates a scalable noise characterisation protocol suited to this key context. First, we introduce this protocol by building upon averaged circuit eigenvalue sampling (ACES), a framework for noise characterisation experiments that simultaneously estimates the Pauli error probabilities of all gates in a Clifford circuit and captures averaged spatial correlations between gates implemented simultaneously in the layers of the circuit. We demonstrate the scalability and performance of our protocol through circuit-level numerical simulations of the entire noise characterisation procedure. Then we demonstrate in circuit-level numerical simulation that this protocol is practically capable of calibrating a fast correlated matching decoder, enabling noise-aware decoding. We find that noise-aware decoding increases the error suppression factor of the code, leading to reductions in the logical error rate that increase exponentially with the code distance. Finally, we present several results obtained from experimentally implementing this protocol. We use the noise characterisation results to design an improved syndrome extraction circuit for a heavy hexagon memory that is adapted to the noise characteristics of the quantum device. The model error of our noise characterisation results suggests that the circuit-level Pauli noise model estimated by ACES can describe the essential features of quantum noise. We also operate a heavy hexagon memory and use noise estimates to predict performance and inform decoding. These results demonstrate that Pauli noise estimates can calibrate decoders to enable noise-aware decoding and inform the co-design of quantum error correcting codes, decoders, fault-tolerant circuits, and quantum devices.

Crispin W. Gardiner, P. Zoller