A qubit strongly-coupled to a resonant cavity: asymmetry of the spontaneous emission spectrum beyond the rotating wave approximation

Understand

We investigate the spontaneous emission spectrum of a qubit in a lossy resonant cavity.

• We use neither the rotating-wave approximation nor the Markov approximation.
• The qubit-cavity coupling strength is varied from weak, to strong, even to lower bound of the ultra-strong.
• For the weak-coupling case, the spontaneous emission spectrum of the qubit is a single peak, with its location depending on the spectral density of the qubit environment.