Experimental observation of the dual behavior of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="script">PT</mml:mi></mml:math>-symmetric scattering

Abstract

We investigate experimentally parity-time ($\mathcal{PT}$) symmetric scattering using $LRC$ circuits in an inductively coupled $\mathcal{PT}$-symmetric pair connected to transmission line leads. In the single-lead case, the $\mathcal{PT}$-symmetric circuit acts as a simple dual device---an amplifier or an absorber depending on the orientation of the lead. When a second lead is attached, the system exhibits unidirectional transparency for some characteristic frequencies. This nonreciprocal behavior is a consequence of generalized (nonunitary) conservation relations satisfied by the scattering matrix.