  We present the experimental demonstration of the occurrence of exceptional
points of degeneracy (EPDs) in a single resonator by introducing a linear
time-periodic variation of one of its components, in contrast to EPDs in parity
time (PT)-symmetric systems that require two coupled resonators with precise
values of gain and loss. In the proposed scheme, only the tuning of the
modulation frequency is required that is easily achieved in electronic systems.
The EPD is a point in a system parameters' space at which two or more
eigenstates coalesce, and this leads to unique properties not occurring at
other non-degenerate operating points. We show theoretically and experimentally
the existence of a second order EPD in a time-varying single resonator.
Furthermore, we measure the sensitivity of the proposed system to a small
structural perturbation and show that the operation of the system at an EPD
dramatically boosts its sensitivity performance to very small perturbations.
Also, we show experimentally how this unique sensitivity induced by an EPD can
be used to devise new exceptionally-sensitive sensors based on a single
resonator by simply applying time modulation.
