Interference and Interferometry

Lawrence N. Mertz

G. S. Agarwal, Pradyumna K. Pathak, Marlan O. Scully

Implications of field quantization on Ramsey interferometry are discussed and general conditions for the occurrence of interference are obtained. Interferences do not occur if the fields in two Ramsey zones have a precise number of photons. However, in this case we show how an analog of Hanbury-Brown Twiss photon-photon correlation interferometry can be used to discern a variety of interference effects as the two independent Ramsey zones get entangled by the passage of the first atom. Interferences are restored by working with fields at a single-photon level. Generation of entangled states including states such as $|2,0〉{+e}^{i\ensuremath{\theta}}|0,2〉$ is discussed.

Sheng-Chang Li, Libin Fu, Jie Liu

We investigate Landau-Zener-St\"uckelberg-Majorana (LZSM) interferometry in a nonlinear two-level system subjected to a sinusoidal driving field. A comprehensive analysis for the interference patterns is shown from which we can analytically obtain the condition of constructive and destructive interferences in some cases. In the presence of nonlinear interaction, the level structure is changed, which can lead to an asymmetric deformation of the interference patterns and a significant position shift of the interference fringes. Our findings suggest an application of the nonlinear LZSM interferometry in accurately calibrating the parameters characterizing a nonlinear two-level system, as well as its coupling with the driven fields.

Peter Hawkes, Erwin K. Kasper

Chaojie Wang, Yuning Zhang, Yuanyuan Chen +2 more

Quantum interferometry provides a pivotal method for investigating complex photon-photon interaction, enabling various quantum information technologies that beyond the possibilities of classical physics. While such an effective interaction is mostly studied in N × N unitary transformation, m × n nonunitary transformation that relates to lossy multiport quantum interferometry requires a different approach. Here, we experimentally demonstrate a concise yet powerful tool to unravel fundamental features of multiport quantum interferometry with universal nonunitary transformations. To confirm their intriguing unitary and nonunitary properties, Hong-Ou-Mandel (HOM) interference is observed to reveal its nontrivial particle exchange phase, wherein the conventional HOM interference based on unitary transformation and the anomalous HOM interference based on nonunitary transformation can be readily harnessed. These results provide an alternative approach to investigate the quantum light-matter interaction, facilitating the use of complex multiport quantum interference for large-scale quantum information processing tasks such as quantum simulation and quantum computation.