2020/06/30 by Tao Xin · 9 citations
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Computer science #Mathematical analysis #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum algorithm #Quantum and electron transport phenomena #Quantum computer #Quantum mechanics #Quantum state #Quantum tomography #Qubit #Robustness (evolution) #Scheme (mathematics) #State (computer science) #Tomography #quant-ph
paper · pdf · doi:10.1103/physreva.102.052410
published in Physical Review A 102(5) (American Physical Society) · 11 pages, 7 figures. To be published in PRA
arxiv created 2020/10/20 · openalex publication_date 2020/11/10 · arxiv updated 2020/11/18 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
Quantum device characterization via state tomography plays an important role in both validating quantum hardware and processing quantum information, but it needs the exponential number of the measurements. For the systems with XX+YY-type couplings and Z readouts, such as superconducting quantum computing (SQC) systems, traditional quantum state tomography (QST) using single-qubit readout operations at least requires 3n measurement settings in reconstructing an n-qubit state. In this paper, I propose an improved QST by adding two-qubit evolutions as the readout operations and obtain an optimal tomographic scheme using the integer programming optimization. I, respectively, apply the alternative scheme on SQC systems with the nearest-neighbor, two-dimensional, and all-to-all connectivities on qubits. It shows that this method can reduce the number of measurements by over 60% compared with the traditional QST. In addition, comparison with the traditional scheme in the experimental feasibility and robustness against errors was made by numerical simulation. It is found that the alternative scheme has good implementability and can achieve comparable or even better accuracy than the traditional scheme. It is expected that the experimentalist from related fields can directly utilize the ready-made results for reconstructing quantum states involved in their research.