Bose–Einstein condensation of photons in an erbium–ytterbium co-doped fiber cavity

Abstract

Bose–Einstein condensation (BEC) is a special many-boson phenomenon that was observed in atomic particles at ultra-low temperatures. Later, BEC was also shown for non-atomic bosons, such as photons. Those experiments were usually done in micron-size cavities, where the power (particle number) was varied, and not the temperature, until condensation was reached. Here we demonstrate BEC of photons in a few-meters-long one-dimensional (1D) erbium–ytterbium co-doped fiber cavity at, below and above room temperature, between 100 K and 415 K. The experiments were done at about the 1550 nm wavelength regime having a few to tens of μW intra-cavity light power (107−108 photons). By varying the power and also the temperature, we found linear dependence of the condensation on power for various temperatures and of the critical power (for condensation) on temperature. These findings agree, functionally and quantitatively, with the theoretical BEC prediction without any adjustable parameter.

Sub-picosecond thermalization dynamics in condensation of strongly coupled lattice plasmons

“…We observe a unique double-threshold phenomenon where one-dimensional (1D) lasing occurs for lower pump fluences and 2D multimode condensation, associated with thermalization, at higher fluences. The transition between lasing and condensation shown in our work is different from previous condensates 16,28,[32][33][34][35][36] : it relies on matching the system size, propagation of excitations, and the thermalization dynamics. Importantly we find a peculiar intermediate regime showing features of a thermalization process but no macroscopic population at the lowest energy states.…”

“…It has been shown both experimentally and theoretically that, in the weak coupling regime, recurrent absorption and emission processes of light with molecules whose vibrational manifold is coupled to an external bath lead to thermalization and condensation with a BE(-type) distribution. This occurs both for continuous wave 19,33,36,53 and pulsed 28,54,55 pumping. The vibrational manifold serves as the energy loss channel to move the photon population towards lower energies, and thermal population of the vibrational states provides the temperature for the BE distribution.…”

Wave condensation with weak disorder versus beam self-cleaning in multimode fibers

“…Bose-Einstein condensation refers to a quantum process characterized by a thermodynamic transition into a single, macroscopically populated coherent state. This phenomenon has been observed in a variety of quantum systems, such as ultracold atoms and molecules [1], exciton polaritons [2] and photons [3] (also see [4]). On the other hand, several studies on wave turbulence predicted that completely classical waves can undergo a condensation process [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

Classical Rayleigh-Jeans Condensation of Light Waves: Observation and Thermodynamic Characterization

“…In this way, the parameters (n eq 0 , µ) have been retrieved by a least square method from the theoretical expressions Eqs. (2)(3)(4). Figs.…”