Leakage Reduction in Single Qubit Gates on Transmon Qubits

Fast quantum logic gates are desirable to reduce errors due to decoherence. In qubit systems with low to moderate nonlinearity, such as the transmon, a primary limit to the gate speed is coherent leakage outside the computational subspace. Historically, this challenge has been addressed by engineering a spectral notch around the |1> to |2> transition frequency using DRAG [1,2]. In this talk, we introduce a novel pulse shaping technique to reduce leakage in fast single qubit gates. We describe a calibration procedure that can be used to realize these control pulses and present experimental results.

[1] F. Motzoi and F. K. Wilhelm. “Improving frequency selection of driven pulses using derivative-based transition suppression”, Phys. Rev. A 88, 062318 (2013)

[2] Chen et al. “Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit”, Phys. Rev. Lett. 116, 020501 (2016)