Boulder ion trapping group realizes most robust high-fidelity quantum gate for trapped-ion hyperfine qubits proposed recently by QESSENCE team
by: A. Bermudez, M. B. Plenio
In the race towards a scalable quantum computer, there is a clear and well-defined goal that must be addressed both theoretically and experimentally: the possibility of performing single- and two-qubit gates below the fault-tolerance threshold where quantum-error correction can be applied.Trapped-ion architectures enjoy a privileged position among the different platforms for quantum information processing. In particular, the possibility of exploiting the benefits of microwave radiation for the so-called hyperfine trapped-ion qubits, has already allowed experimentalists to beat the fault-tolerance threshold for one-qubit gates .In a recent work , it has been proposed how to merge the benefits of microwave and laser radiation, in order to beat the FT for two-qubit gates. The main idea is to use the lasers to drive the two-qubit gate, while the microwave is continuously applied to protect the quantum information from different sources of noise (thermal noise, fluctuating magnetic fields or any other pure dephasing noise, and drifting laser phases). This intrinsic robustness has allowed the experimental team lead by D. J. Wineland at NIST  to implement this new gate scheme achieving the best fidelities for hyperfine two-qubit gates to date (97.4%). Although reaching the fault-tolerance threshold will still require further technological developments, the hybrid laser-microwave scheme [2,3] seems to point in the right direction.References: K. Brown, A. C. Wilson, Y. Colombe, C. Ospelkaus, A. M. Meier, E. Knill, D. Leibfried, and D. J. Wineland, Phys. Rev. A 84, 030303(R) (2011) A. Bermudez, P. O. Schmidt, M. B. Plenio, and A. Retzker, Phys. Rev. A 85, 040302(R) (2012). T. R. Tan, J. P. Gaebler, R. Bowler, Y. Lin, J. D. Jost, D. Leibfried, and D. J. Wineland, "Demonstration of a dressed-state phase gate for trapped ions", arXiv:1301.3786 (2013)
Workpackage: wp-3.5: Entanglement-based quantum information processing
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