The Autler-Townes Effect In A Three Dimensional Superconducting Transmon Qubit

Being a promising candidate to physically implement the quantum computer,superconducting quantum bits(qubit)has attracted the attention of the research groups and giants like google and IBM.The superconducting qubit is characteristic of its advantage to be integrated and scaled.In recent years,the increase of the coherence time of the superconducting qubits makes it more likely to implement the first quantum computer.We start with the 3D transmon first claimed by Yale,and research the qubit system on the basis of the 3D transmon.Our study includes:We made the 3D transmon by coupling the superconducting qubits with the 3D cavity.Also we build the qubit measurement system with high synchronization,high sampling rate,and fast readout which consists of signal control part in room temperature,and noise isolation and route switch part in mK temperature using the Triton400 dilution refrigerator as extremely low temperature platform.We are able to characterize the several qubit parameters such as transition frequency,Rabi Oscillation,energy relation and phase decoherence etc.We measured the first and second excited states and two photon transition frequency in a 3D transmon.We observed Autler-Townes effect with different combination of coupler and probe drive using both single and two photon transition frequency.By comparing the Rabi oscillation of coupler field with the gap between the ATS doublets,we discuss the relation of the ATS and coupler drive power in both single and two-photon system.The numerical calculation fits well with our experiment.We study how Poisson noise affect AT effect in a qubit system by modulating the coupler drive with a random telegraph noise.By generating RTN with different jumping rates,we observe the motional averaging phenomenon when the jumping rates reaches certain threshold and discuss that threshold with the coupler drive of ATE.We calculate the density matrix and it is consistent with the experiment data.