Fidelity estimation and entanglement verification for experimentally produced four-qubit cluster states

Journal Article · Tue Aug 15 00:00:00 EDT 2006 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.74.020301· OSTI ID:20853003

Tokunaga, Yuuki ^[1]; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki ^[2]

---

1. NTT Information Sharing Platform Laboratories, NTT Corporation, 1-1 Hikari-no-oka, Yokosuka, Kanagawa 239-0847 (Japan)
2. Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

We propose methods of fidelity estimation and entanglement verification for experimentally produced four-qubit cluster states. We show that we can obtain a high lower bound of the fidelity using only four local projective measurement settings. The lower bound is close to the exact fidelity, which is determined only by at least nine local projective measurement settings. We also present witness operators for distinguishing entanglement around a four-qubit cluster state from specific classes of genuine four-qubit entanglement, e.g., a class including GHZ and W types of entanglement.

• OSTI ID: 20853003
• Journal Information: Physical Review. A, Vol. 74, Issue 2; Other Information: DOI: 10.1103/PhysRevA.74.020301; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ENERGY LEVELS
QUANTUM ENTANGLEMENT
QUANTUM MECHANICS
QUANTUM NUMBERS
QUBITS
VERIFICATION