Pendry J B
Opt Express. 2023 Jan 2;31(1):452-458. doi: 10.1364/OE.476961.
Time dependent systems in general do not conserve photons nor do they conserve energy. However when parity-time symmetry holds Maxwell's equations can sometimes both conserve photon number and energy. Here we show that photon conservation is the more widely applicable law which can hold in circumstances where energy conservation is violated shedding further light on an amplification mechanism identified in previous papers as a process of conserved photons climbing a frequency ladder.
一般来说，含时系统既不守恒光子数，也不守恒能量。然而，当宇称 - 时间对称性成立时，麦克斯韦方程组有时既能守恒光子数，又能守恒能量。在此我们表明，光子守恒是更具广泛适用性的定律，在能量守恒被违背的情况下它仍能成立，这进一步揭示了在先前论文中被认定为守恒光子攀爬频率阶梯过程的一种放大机制。
