Theoretical study of reflection spectroscopy for superconducting quantum parametrons

Abstract

Superconducting parametrons in the single-photon Kerr regime, also called KPOs, have been attracting increasing attention in terms of their applications to quantum annealing and universal quantum computation. It is of practical importance to obtain information of superconducting parametrons operating under an oscillating pump field. Spectroscopy can provide information of a superconducting parametron under examination, such as energy level structure and occupation of energy levels, and also useful information for calibration of the pump field. We theoretically study the reflection spectroscopy of superconducting parametrons, and develop a method to obtain the reflection coefficient. We present formulae of the reflection coefficient, the nominal external and the internal decay rates, and examine the obtained spectra.

Quantum Gate for Kerr Nonlinear Parametric Oscillator Using Effective Excited States

“…Also a crossover from a JPO to a KPO has been observed [25]. Related theoretical analyses have been reported [26,27].…”

“…The rest of the eigenstates can be considered as effective excited states in the rotating frame, which we refer to as the excited states in the following. These excited states can be detected spectroscopically [25,27]. The parity of an excited state |E k is the same as that of the integer k, because k coincides with the photon number of the eigenstate at p 0 /K = 0, and the parametric drive preserves the parity.…”