arXiv subjects

Henry J. Hesten

Publications and source records attributed to Henry J. Hesten.

5 recordsLinked to original sources

arXiv2019

Collective excitation profiles and the dynamics of photonic condensates

Photonic condensates are complex systems exhibiting phase transitions due to the interaction with their molecular environment. Given the macroscopic number of molecules that form a reservoir of excitations, numerical simulations are expensive, even for systems with few cavity modes. We present a systematic construction of molecular excitation profiles with a clear hierarchical ordering, such that only modes in the lowest order in the hierarchy directly affect the cavity photon dynamics. In addition to a substantial gain in computational efficiency for simulations of photon dynamics, the explicit spatial shape of the mode profiles offers a clear physical insight into the competition among the cavity modes for access to molecular excitations.

quant-ph↗

arXiv2019

Non-critical slowing down of photonic condensation

We investigate the response of a photonic gas interacting with a reservoir of pumped dye-molecules to quenches in the pump power. In addition to the expected dramatic critical slowing down of the equilibration time around phase transitions we find extremely slow equilibration even far away from phase transitions. This non-critical slowing down can be accounted for quantitatively by fierce competition among cavity modes for access to the molecular environment, and we provide a quantitative explanation for this non-critical slowing down.

quant-ph↗

arXiv2018

Driven-dissipative, non-equilibrium Bose-Einstein condensation of just a few photons

Coherence is a defining feature of quantum condensates. These condensates are inherently multimode phenomena and in the macroscopic limit it becomes extremely difficult to resolve populations of individual modes and the coherence between them. In this work we demonstrate non-equilibrium Bose-Einstein condensation (BEC) of photons in a sculpted dye-filled microcavity, where threshold is found for $8\pm 2$ photons. With this nanocondensate we are able to measure occupancies and coherences of individual energy levels of the bosonic field. Coherence of individual modes generally increases with increasing photon number, but at the breakdown of thermal equilibrium we observe multimode-condensation phase transitions wherein coherence unexpectedly decreases with increasing population, suggesting that the photons show strong inter-mode phase or number correlations despite the absence of a direct nonlinearity. Experiments are well-matched to a detailed non-equilibrium model. We find that microlaser and Bose-Einstein statistics each describe complementary parts of our data and are limits of our model in appropriate regimes, which informs the debate on the differences between the two.

quant-ph↗

arXiv2017

Decondensation in non-equilibrium photonic condensates: when less is more

We investigate the steady state of a system of photons in a pumped dye-filled microcavity. By varying pump and thermalization the system can be tuned between Bose-Einstein condensation, multimode condensation, and lasing. We present a rich non-equilibrium phase diagram which exhibits transitions between these phases, including decondensation of individual modes under conditions that would typically favor condensation.

cond-mat.quant-gas↗

arXiv2016

Spatiotemporal coherence of non-equilibrium multimode photon condensates

We report on the observation of quantum coherence of Bose-Einstein condensed photons in an optically-pumped, dye-filled microcavity. We find that coherence is long-range in space and time above condensation threshold, but short-range below threshold, compatible with thermal-equilibrium theory. Far above threshold, the condensate is no longer at thermal equilibrium and is fragmented over non-degenerate, spatially overlapping modes. A microscopic theory including cavity loss, molecular structure and relaxation shows that this multimode condensation is similar to multimode lasing induced by imperfect gain clamping.

cond-mat.quant-gas↗