Efficient control pulses for continuous quantum gate families through coordinated re-optimization

Abstract

We present a general method to quickly generate high-fidelity control pulses for any continuouslyparameterized set of quantum gates after calibrating a small number of reference pulses. We pick several reference operations in the gate family of interest and directly optimize pulses that implement these operations, then iteratively re-optimize the pulses to guide their shapes to be similar for operations that are closely related. A straightforward interpolation method can then obtain highfidelity pulses for arbitrary operations in the continuous set. We demonstrate this procedure on the three-parameter Cartan decomposition of two-qubit gates to obtain control pulses for any two-qubit gate, up to single-qubit operations, with consistently high fidelity. The method generalizes to any number of gate parameters and can be used with any pulse optimization algorithm.

Direct pulse-level compilation of arbitrary quantum logic gates on superconducting qutrits

“…Min-imizing the number of gates and the total operation time can significantly reduce the errors accumulating per gate and over time. General qutrit gates can be decomposed into Z (01) Z (12) Y (12) Y (01) Z (01) Z (12) Y (01) Z (01) Z (12) , where each Y and Z gates have different rotation angles. The Y gates can be further decomposed into Z θ1 X π/2 Z θ2 X π/2 Z θ3 [28], where θ 1 , θ 2 , and θ 3 are rotation angles.…”

“…Recently, optimal control algorithms have been developed for closed and open quantum systems [8][9][10][11][12] to find accurate pulses efficiently. Experimental demonstrations with single qubit gates [13,14], 0-2 swap qutrit gate [15], and two qubit gates [16] show that optimal control can be used for universal control of a quantum system.…”