Superconducting quantum circuits have emerged as a promising test bed for probing phenomena involving light-matter interaction. In this talk I will mainly discuss experimental results from measurement of a 'circuit quantum electrodynamics' system – a superconducting ' transmon' qubit coupled to a superconducting lumped element microwave resonator measured at 20mK . I will discuss the basic Jaynes-Cummings Hamiltonian that describes the system, and discuss results from three experiments – viz. (a) First experimental observation of Autler-Townes splitting of 'dressed' Jaynes-Cummings levels (b) Nonlinear dependence of microwave photon occupancy in the resonator (c) Achieving coherent population trapping in a superconducting circuit. In the latter part of the talk, I will also discuss my current work in the emerging field of Quantum Acoustics, where the artificial atom interacts with surface phonons on a piezo electric substrate.