Anti-Parity-Time Symmetric Optical Four-Wave Mixing in Cold Atoms
Anti-Parity-Time Symmetric Optical Four-Wave Mixing in Cold Atoms
Non-Hermitian optical systems with parity-time ($PT$) symmetry have recently revealed many intriguing prospects that outperform conservative structures. The previous works are mostly rooted in complex arrangements with controlled gain-loss interplay. Here, we demonstrate anti-$PT$ symmetry inherent in the nonlinear optical interaction based upon forward optical four-wave mixing in a laser-cooled …