Rambach Markus, Qaryan Mahdi, Kewming Michael, Ferrie Christopher, White Andrew G, Romero Jacquiline
Australian Research Council Centre of Excellence for Engineered Quantum Systems, Brisbane, Queensland 4072, Australia.
School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia.
Phys Rev Lett. 2021 Mar 12;126(10):100402. doi: 10.1103/PhysRevLett.126.100402.
The exponential growth in Hilbert space with increasing size of a quantum system means that accurately characterizing the system becomes significantly harder with system dimension d. We show that self-guided tomography is a practical, efficient, and robust technique of measuring higher-dimensional quantum states. The achieved fidelities are over 99.9% for qutrits (d=3) and ququints (d=5), and 99.1% for quvigints (d=20)-the highest values ever realized for qudit pure states. We also show excellent performance for mixed states, achieving average fidelities of 96.5% for qutrits. We demonstrate robustness against experimental sources of noise, both statistical and environmental. The technique is applicable to any higher-dimensional system, from a collection of qubits through to individual qudits, and any physical realization, be it photonic, superconducting, ionic, or spin.
随着量子系统规模的增大，希尔伯特空间中的指数增长意味着，随着系统维度d的增加，精确表征该系统变得显著困难。我们表明，自引导层析成像是一种实用、高效且稳健的测量高维量子态的技术。对于三量子位（d = 3）和五量子位（d = 5），实现的保真度超过99.9%，对于二十量子位（d = 20），保真度为99.1%，这是量子比特纯态所实现的最高值。我们还展示了混合态的出色性能，三量子位的平均保真度达到96.5%。我们证明了该技术对统计和环境等实验噪声源具有鲁棒性。该技术适用于任何高维系统，从量子比特集合到单个量子比特，以及任何物理实现方式，无论是光子、超导、离子还是自旋实现方式。
