2020/02/29 by Xinhe Jiang, Xin-he Jiang, Kun Wang +9 · 34 citations
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Computer science #Function (biology) #Limit (mathematics) #Mathematical analysis #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum computer #Quantum mechanics #Quantum state #Qubit #Scaling #Standardization #State (computer science) #Statistical physics #physics.optics #quant-ph
paper · pdf · doi:10.1038/s41534-020-00317-7
published in npj Quantum Information 6(1) (Nature Portfolio) · 16+19 pages, 6+10 figures
openalex created_date 2020/02/07 · openalex publication_date 2020/10/27 · arxiv created 2021/01/18 · arxiv updated 2021/01/19 · openalex updated_date 2026/08/05
Abstract Quantum devices for generating entangled states have been extensively studied and widely used. As so, it becomes necessary to verify that these devices truly work reliably and efficiently as they are specified. Here we experimentally realize the recently proposed two-qubit entangled state verification strategies using both local measurements (nonadaptive) and active feed-forward operations (adaptive) with a photonic platform. About 3283/536 number of copies ( N ) are required to achieve a 99% confidence to verify the target quantum state for nonadaptive/adaptive strategies. These optimal strategies provide the Heisenberg scaling of the infidelity \itε <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϵ</mml:mi> </mml:math> as a function of N ( \itε ∼ Nr <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ϵ</mml:mi> <mml:mo>~</mml:mo> <mml:msup> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ) with the parameter r = −1, exceeding the standard quantum limit with r = −0.5. We experimentally obtain the scaling parameters of r = − 0.88 ± 0.03 and − 0.78 ± 0.07 for nonadaptive and adaptive strategies, respectively. Our experimental work could serve as a standardized procedure for the verification of quantum states.