Fluctuations of the electromagnetic local density of states as a probe for structural phase switching

We study the statistics of the fluorescence decay rates for single quantum emitters embedded in a scattering medium undergoing a phase transition. Under certain circumstances, the structural properties of the scattering medium explore a regime in which the system dynamically switches between two different phases. While in that regime the light-scattering properties of both phases are hardly distinguishable, we demonstrate that the lifetime statistics of single emitters with low diffusivity is clearly dependent on the dynamical state in which the medium evolves. Hence, lifetime statistics provides clear signatures of phase switching in systems where light scattering does not.

Figure 1

Normalized decay-rate (equal to the LDOS normalized to the vacuum one) spectrum of a single emitter placed at the center of a cluster at $T=0$ (see text for further details). Inset: the system under study. Each point scatterer is replaced by a sphere of radius $r_m/2$. The translucid sphere represents the confining sphere.

Figure 2

(a) Energy-per-particle sampling at $T=0.6$ as a function of the MC steps. (b) Corresponding pair-correlation function among scatterers $g\left(r\right)$ for the high-energy branch [red (gray)] and for the low-energy branch (black). (c) Energy-scattering efficiency sampling at the switching region $\left(T=0.6,r_m/\lambda =0.872\right)$; red (gray) dots correspond to high-energy states and black dots correspond to low-energy states. (d) Corresponding scattering efficiency distributions for the upper energy branch [red (gray) curve] and lower energy branch (black curve) corresponding to liquid and solid phases, respectively. The shaded area corresponds to the sum of both high- and low-energy distributions.

Figure 3

Energy-per-particle decay-rate sampling at the switching region $\left(T=0.6\right)$ for different ratios $r_m/\lambda$: (a) $r_m/\lambda =0.466$, (c) $r_m/\lambda =0.872$. (b), (d) The corresponding decay-rate distributions are shown after integrating in energies: black histograms correspond to the solid phase, red (gray) ones correspond to the liquid phase, and the shaded gray areas correspond to the total measured decay rates (sum of both solid and liquid distributions).

Figure 4

Emitter radial distribution function (ERDF) for scatterers surrounding the emitter at the phase-switching region $\left(T=0.6\right)$. Black and red (gray) curves represent the solid and liquid region, respectively.