Long-distance coupling and energy transfer between exciton states in magnetically controlled microcavities

Realization of the strong coupling and energy transfer between spatially separated, and selectively addressable, semiconductor quantum emitters is essential for practical implementation of quantum information technology protocols. Here, we design and fabricate epitaxially a structure comprising two (Cd,Zn)Te based microcavities separated by over 2 µm and coupled through a semitransparent Bragg mirror.[1] Coupling of the emitter to the mode of one of the microcavities enables its interaction with a distant emitter coupled to mode of the other microcavity. A non-magnetic quantum well (QW) and mangetic, Mn-doped quantum well (MQW) is placed in the top and bottom microcavity, respectively. The magneto-photoluminescence measurements performed at T = 2 K demonstrate anticrossing of the polariton states for which a dominant contribution comes from QW and MQW excitons. Emission intensity dependences confirm energy transfer between the exciton states over the unprecedented distance of 2.1 µm. Control over the direction of the transfer is achieved by tuning of the exciton energy in MQW below or above the exciton in the QW using magnetic field.[1]

[1] M. Sciesiek, K. Sawicki, W. Pacuski, K. Sobczak, T. Kazimierczuk, A. Golnik, and Suffczynski, Communications Materials 1, 78 (2020).