We suggest overcoming the "Rayleigh catastrophe" and reaching superresolution for imaging with both spatially and temporally-correlated field of a superradiant quantum antenna. Considering farfield radiation of two interacting spontaneously emitting two-level systems, we show that for the measurement of the temporally-delayed second-order correlation function of the scattered field, the Fisher information does not tend to zero with diminishing the distance between a pair of scatterers even for non-sharp time-averaged detection. For position estimation of a larger number of scatterers, measurement of the time-delayed function is able to provide a considerable accuracy gain over the zero-delayed function. We show also that the superresolution with the considered quantum antenna can be achieved for both near-field imaging and estimating parameters of the antenna.

In this paper, we show how designed loss in open quantum systems can break the reciprocity of field propagation, and how non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear. In particular, we show how unidirectional propagation can be achieved for input states of certain symmetry in linear schemes, and demonstrate the possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build a non-reciprocal asymmetric field distributor with a planar structure of dissipatively coupled waveguides. We discuss the feasibility of the considered schemes and suggest possible realizations.

A quantum antenna consisting of a set of two-level atoms situated on a straight line and prepared in different initial states is investigated. It is shown that radiation in defi ned directions can be totally suppressed if the initial state of the quantum antenna is a symmetric Dicke state. The probability of simultaneous detection of photons in these directions is equal to zero. This result is impossible for the pseudo-classical symmetric initial state of the antenna that does not have quantum entanglement. The probability of detecting a photon at any angle is always nonzero for such a state. The qualitative difference of the interference mechanism for the pseudo-classical and quantum antenna states is described.