Parity-time Symmetry Based on Time Modulation
Huanan Li, Hady Moussa, Dimitrios L. Sounas, Andrea Alù
Abstract
Give and take: Conventionally a delicate balance between gain and loss is critical to implementing effects based on parity-time ($P\phantom{\rule{0}{0ex}}T$) symmetry, which hinders this approach in a variety of physical contexts. This study presents $P\phantom{\rule{0}{0ex}}T$ symmetry in systems $w\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}h\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}t$ gain and loss, leveraging instead energy storage and release based on slow modulations in time. The authors induce unusual responses typical of $P\phantom{\rule{0}{0ex}}T$-symmetric systems in a fully $c\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}e$ structure. These results pave the way to exploring $P\phantom{\rule{0}{0ex}}T$ symmetry in quantum mechanical settings, and to innovative applications that can overcome current technological limitations of passive systems.