2ND QUANTIZATION OF OPEN SYSTEMS USING QUASI-NORMAL MODES

The second quantization of a scalar field in an open cavity is formula ted, from first principles, in terms of the quasinormal modes (QNMs), which are the eigensolutions of the: evolution equation that decay exp onentially in time as energy leaks to the outside. For any amount of d amping, this formulation provides an exact description involving the c avity degrees of freedom only, with the outside acting as a (thermal o r driven) source. Thermal correlation functions and cavity Feynman pro pagators are thus expressed in terms of the QNMs, labeled by a discret e index rather than a continuous momentum. Single-resonance domination ;of the density of states and the spontaneous decay rate is then given a proper foundation. This is an essential first step towards the appl ication of QNMs to cavity quantum electrodynamics phenomena, to be rep orted elsewhere.