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Abstract Coherent control and manipulation of quantum degrees of freedom such as spins forms the basis of emerging quantum technologies. In this context, the robust valley degree of freedom and the associated valley pseudospin found in two‐dimensional transition metal dichalcogenides is a highly attractive platform. Valley polarization and coherent superposition of valley states have been observed in these systems even up to room temperature. Control of valley coherence is an important building block for the implementation of valley qubit. Large magnetic fields or high‐power lasers have been used in the past to demonstrate the control (initialization and rotation) of the valley coherent states. Here, the control of layer–valley coherence via strong coupling of valley excitons in bilayer WS₂to microcavity photons is demonstrated by exploiting the pseudomagnetic field arising in optical cavities owing to the transverse electric–transverse magnetic (TE–TM)mode splitting. The use of photonic structures to generate pseudomagnetic fields which can be used to manipulate exciton‐polaritons presents an attractive approach to control optical responses without the need for large magnets or high‐intensity optical pump powers. 

Abstract A negative‐capacitance high electron mobility transistor (NC‐HEMT) with low hysteresis in the subthreshold region is demonstrated in the wide bandgap AlGaN/GaN material system using sputtered BaTiO₃as a “weak” ferroelectric gate in conjunction with a conventional SiN_xdielectric. An enhancement in the capacitance for BaTiO₃/SiN_xgate stacks is observed in comparison to control structures with SiN_xgate dielectrics directly indicating the negative capacitance contribution of the ferroelectric BaTiO₃layer. A significant reduction in the minimum subthreshold slope for the NC‐HEMTs is obtained in contrast to standard metal‐insulator‐semiconductor HEMTs with SiN_xgate dielectrics—97.1 mV dec⁻¹versus 145.6 mV dec⁻¹—with almost no hysteresis in theI_D–V_Gtransfer curves. These results are promising for the integration of ferroelectric perovskite oxides with III‐Nitride devices toward NC‐field‐effect transistor switches with reduced power consumption.