Optimal and robust experiment design for quantum state tomography of star-topology register

TL;DR

This paper introduces an optimized and robust quantum state tomography method tailored for star-topology quantum registers, reducing measurement complexity and enhancing error resilience, demonstrated on a 10-spin system.

Contribution

It presents a novel tomography strategy leveraging star-symmetry to simplify measurements and optimize information transfer, suitable for large-scale, constrained quantum systems.

Findings

Reduced number of measurements needed for tomography

Enhanced robustness against measurement errors

Successful characterization of a 10-spin star-topology register

Abstract

While quantum state tomography plays a vital role in the verification and benchmarking of quantum systems, it is an intractable task if the controllability and measurement of quantum registers are constrained. In this paper, we study the quantum state tomography of star-topology registers, in which the individual addressability of peripheral spins is infeasible. Based on the star-symmetry, we decompose the Hilbert space to alleviate the complexity of tomography and design a compact strategy with minimum number of measurements. By optimizing the parameterized quantum circuit for information transfer, the robustness against measurement errors is also improved. Furthermore, we apply this method to a 10-spin star-topology register and demonstrate its ability to characterize large-scale systems. Our results can help future investigations of quantum systems with constrained ability of quantum control and measurement.