AQP Seminar: Metrological algorithms and noise measurements with a transmon artificial atom

Modern research in the quantum metrology has shown that the accuracy of measurements of physical quantities can be fundamentally improved. At the same time coplanar superconducting quantum circuits comprising a transmon type artificial atom represents very simple but very fruitful simulator of light-matter interaction, therefore it can be used as a platform for quantum metrology. 

It has been demonstrated that a transmon qubit can be used as an high-precision magnetic-field sensor [npj Quantum Informationvolume 4, 29]. We show that the superconducting transmon device operated in a qutrit (3-level system) mode offers an enhanced performance as a magnetic-field sensor. Moreover, we show that the accounting effects of dephasing requires a change in metrological algorithm: it can be optimized in the 3-level system case, which can not be done in the 2-level case.

Besides applications in quantum metrology, it is useful to exploit such a transmon-based platform for transport characterization in a mesoscopic device. We present a strategy for the measurement of the Full Counting Statistics (the complete characterization of the charge transport) with a transmon artificial atom.