Quantum state engineering of multi-mode and entangled optical fields using photon counting

Nonclassical states, having negative Glauber-Sudarshan P-function, do not have a classical analogue. These states have paved way for second quantum revolution and photonic quantum technology. A few examples of generation of such states in nonlinear optical processes and its challenges will be discussed. Photon number measurements and post-selection make a plethora of quantum state engineering operations feasible. Quantum state engineering using non-Gaussian operations provides powerful tool for continuous variable quantum information. Practical challenges in their implementation and feasibility of generation of such states will be discussed [1-4]. Twin beams are generated in a nonlinear optical process, namely spontaneous parametric down conversion, under stronger pumping. They are endowed with ideally perfect photon number correlations in the constituting signal and idler beams. This quantum feature is revealed by the sub-shot noise photon number correlations. However, the marginal signal and idler photon number distributions are multimode thermal. We illustrate the generation of engineered multimode quantum states from twin beams by photon subtraction and addition with supporting experimental realization. Future prospects, in view of our results, will be discussed.
[1] K. Thapliyal, J. Peřina Jr., O. Haderka, V. Michálek, and R. Machulka, Experimental characterization of multimode photon-subtracted twin beams, Phys. Rev. Res. 6, 013065 (2024).
[2] J. Peřina Jr., K. Thapliyal, O. Haderka, V. Michálek, and R. Machulka, Generalized sub-Poissonian states of two-beam fields, Opt. Express 32, 537 (2024).
[3] K. Thapliyal, J. Peřina Jr., O. Haderka, V. Michálek, and R. Machulka, Experimental photon addition and subtraction in multi-mode and entangled optical fields, Opt. Lett. 49, 4521 (2024).
[4] J. Peřina Jr., K. Thapliyal, O. Haderka, V. Michálek, and R. Machulka, Sub-Poissonian twin beams, Optica Quantum 2, 148 (2024).