Probing two-qubit capacitive interactions beyond bilinear regime using dual Hamiltonian parameter estimations

This paper reports the simultaneous operation and two-qubit-coupling measurement of a pair of two-electron spin qubits, actively decoupled from quasi-static nuclear noise in a GaAs quadruple quantum dot array. Coherent Rabi oscillations are achieved using real-time Hamiltonian estimators. Strong two-qubit capacitive interaction (>190 MHz) is observed, exceeding the bilinear regime. A high ratio (>16) between coherence and conditional phase-flip time supports high-fidelity, fast quantum entanglement generation using capacitive interaction.

Jonginn Yun, Jaemin Park, Hyeongyu Jang, Jehyun Kim, Wonjin Jang, Younguk Song, Min-Kyun Cho, Hanseo Sohn, Hwanchul Jung, Vladimir Umansky, Dohun Kim