Implementation of all-microwave entanglement schemes in 3D transmon two qubit system

We implemented all-microwave two qubit entanglement scheme via Stark shift-induced controlled phase gate, as suggested by J. Chow et al., [1]. Our system consists of two superconducting transmon qubits, one of which is a tunable-frequency qubit and the other is a fixed-frequency qubit, embedded in a three dimensional copper cavity. As we align higher quantum states outside the computational states, i.e., \textbar 12\textgreater and \textbar 03\textgreater , we could achieve controlled phase gate by applying a microwave tone which induces the Stark shift. The gate time can be controlled depending on how close we align the levels. We will present our results on the estimation of the fidelity of generated Bell states with tomographic reconstruction of the two-qubit states as a function of the gate time. [1] J. Chow et al., New J. Phys. 15, 115012 (2013).