  Yang-Lee edge singularities (YLES) are the edges of the partition function
zeros of an interacting spin model in the space of complex control parameters.
They play an important role in understanding non-Hermitian phase transitions in
many-body physics, as well as characterizing the corresponding nonunitary
criticality. Even though such partition function zeroes have been measured in
dynamical experiments where time acts as the imaginary control field,
experimentally demonstrating such YLES criticality with a physical imaginary
field has remained elusive due to the difficulty of physically realizing
non-Hermitian many-body models. We provide a protocol for observing the YLES by
detecting kinked dynamical magnetization responses due to broken PT symmetry,
thus enabling the physical probing of nonunitary phase transitions in
nonequilibrium settings. In particular, scaling analyses based on our
nonunitary time evolution circuit with matrix product states accurately recover
the exponents uniquely associated with the corresponding nonunitary CFT. We
provide an explicit proposal for observing YLES criticality in Floquet quenched
Rydberg atomic arrays with laser-induced loss, which paves the way towards a
universal platform for simulating non-Hermitian many-body dynamical phenomena.
