|Speaker :||Ray-Kuang Lee (National Tsing-Hua University)|
|Title :||Reflecting on an alternative (parity-time-symmetric) quantum theory, and its analog in optics|
|Time :||2018-03-20 (Tue) 11:00-12:30|
|Place :||Seminar Room 617, Institute of Mathematics (NTU Campus)|
By no-signaling principle, we showed that parity-time (PT)-symmetric quantum theory as an extension of the quantum theory to non-Hermitian Hamiltonians is either a trivial extension or likely false as a fundamental theory . In addition to the implementation PT-symmetric optical systems by carefully and actively controlling the gain and loss, we show that a 2 × 2 PT-symmetric Hamiltonian has a unitarily equivalent representation without complex optical potentials in the resulting optical coupler. Through the Naimark dilation in operator algebra, passive PT-symmetric couplers can thus be implemented with a refractive index of real values and asymmetric coupling coefficients . Moreover, with a phase-space representation on the vicinity of an exceptional point, we show that a PT-symmetric phase transition from an unbroken PT-symmetry phase to a broken one is a second-order phase transition .