TY - JOUR T1 - Robust two-qubit gates in a linear ion crystal using a frequency-modulated driving force JF - Physical Review Letters Y1 - 2018 A1 - Pak Hong Leung A1 - Kevin A. Landsman A1 - Caroline Figgatt A1 - Norbert M. Linke A1 - Christopher Monroe A1 - Kenneth R. Brown AB -

In an ion trap quantum computer, collective motional modes are used to entangle two or more qubits in order to execute multi-qubit logical gates. Any residual entanglement between the internal and motional states of the ions will result in decoherence errors, especially when there are many spectator ions in the crystal. We propose using a frequency-modulated (FM) driving force to minimize such errors and implement it experimentally. In simulation, we obtained an optimized FM gate that can suppress decoherence to less than 10−4 and is robust against a frequency drift of more than ±1 kHz. The two-qubit gate was tested in a five-qubit trapped ion crystal, with 98.3(4)% fidelity for a Mølmer-Sørensen entangling gate and 98.6(7)% for a controlled-not (CNOT) gate. We also show an optimized FM two-qubit gate for 17 ions, proving the scalability of our method.

VL - 120 U4 - 020501 UR - https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.020501 CP - 2 U5 - 10.1103/PhysRevLett.120.020501 ER -