collaborators

5 papers

physics.optics2026

Quantum Photonic Time Crystals: From Temporal Boundaries to Floquet Light-Matter Interactions

Younsung Kim, Kyungmin Lee, Kun Woo Kim +1

Photonic time crystals (PTCs) are temporally periodic media whose Floquet spectra can exhibit momentum gaps, parametric amplification, and effective non-Hermitian descriptions, mak…

physics.optics2026

Energy Transport Velocity in Photonic Time Crystals

Kyungmin Lee, Younsung Kim, Kun Woo Kim +1

Steep or near-vertical Floquet dispersion in photonic time crystals (PTCs) is often read as fast, even apparently superluminal, transport. Here, we demonstrate that this anomaly ar…

physics.optics2026

Classical Petermann Factor as a Measure of Quantum Squeezing in Photonic Time Crystals

Younsung Kim, Kyungmin Lee, Changhun Oh +3

Photonic time crystals realize a continuum of momentum-resolved SU(1,1) parametric amplifiers. We show that a classical quantity, the Petermann factor of the effective Floquet Bogo…

physics.optics2025

Analogs of spontaneous emission and lasing in photonic time crystals

Kyungmin Lee, Minwook Kyung, Yung Kim +7

We report the first direct mapping of the frequency-resolved local density of states (LDOS) in a photonic time crystal (PTC) implemented as an array of time-periodically modulated…

physics.optics2025

Cavity quantum electrodynamics of photonic temporal crystals

Junhyeon Bae, Kyungmin Lee, Bumki Min +1

Photonic temporal crystals host a variety of intriguing phenomena, from wave amplification and mixing to exotic band structures, all stemming from the time-periodic modulation of o…