16-qubit IBM universal quantum computer can be fully entangled

• Published in: npj quantum information Vol. 4; no. 1; pp. 1 - 6
• Main Authors: Wang, Yuanhao, Li, Ying, Yin, Zhang-qi, Zeng, Bei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27-09-2018; Nature Publishing Group
• Subjects: 639/766/483/2802; 639/766/483/481; Classical and Quantum Gravitation; Computers; Physics; Physics and Astronomy; Quantum Computing; Quantum Field Theories; Quantum Information Technology; Quantum Physics; Quantum theory; Relativity Theory; Spintronics; String Theory
• ISSN: 2056-6387; 2056-6387
• DOI: 10.1038/s41534-018-0095-x

Entanglement is an important evidence that a quantum device can potentially solve problems intractable for classical computers. In this paper, we prepare connected graph states involving 8 to 16 qubits on
ibmqx5
, a 16-qubit superconducting quantum processor accessible via IBM cloud, using low-depth circuits. We demonstrate that the prepared state is fully entangled, i.e., the state is inseparable with respect to any fixed partition.
Quantum computing: Sweet sixteen
All sixteen qubits in an IBM Q cloud quantum computer can be fully entangled, a prerequisite for exploiting its quantum computational power. Entanglement is one of the resources that lead to quantum algorithms’ advantages over their classical counterparts. However, even when using the highest-quality qubits it is difficult to produce and verify large-scale entangled states because accumulated errors from imperfect quantum operations can prevent unambiguous confirmation of entanglement. Zhangqi Yin from Tsinghua University and collaborators in China and Canada have shown how to create and verify a sixteen-qubit entangled state using the operations available on IBM’s quantum computing platform, a new record for the number of entangled qubits. While achievable state fidelity remains low for the time being, this result verifies that IBM’s device is truly quantum.