Direct Measurement of the Entanglement of Two Superconducting Qubits via State Tomography
Abstract
The laws of quantum physics provide intriguing possibilities for a tremendous increase in speed compared to classical computation1. Because this power is achieved through the controlled evolution of entangled quantum states, a clear demonstration of entanglement represents a key milestone towards the construction of a scalable quantum computer2,3. Although entanglement can be inferred from simple experiments, a direct demonstration is challenging because all of the DiVincenzo criteria4 for quantum computation must be met simultaneously. Only subsets of these key requirements have been demonstrated previously for superconducting qubits5-9. Here, we demonstrate all of the DiVincenzo criteria simultaneously, thus taking a significant step forward towards placing superconducting qubits on the roadmap for scalable quantum computing. Specifically, capacitively-coupled Josephson phase qubits are used to create Bell states, which when measured using state tomography on both qubits show an entangled state with fidelity of up to 87%. Our results demonstrate a high degree of unitary control of the system, indicating that larger implementations are within reach.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2006
- Accession Number
- AD1005990
Entities
People
- A. N. Cleland
- E. M. Weig
- Erik Lucero
- John M. Martinis
- M. Ansmann
- Matthew Neeley
- Matthias Steffen
- N. Katz
- R. Mcdermott
- Radoslaw C. Bialczak
Organizations
- University of California, Santa Barbara