Phonon-mediated Josephson oscillations in excitonic and polaritonic condensates

Polaritonic Rabi and Josephson Oscillations

The dynamics of coupled condensates is a wide-encompassing problem with relevance to superconductors, BECs in traps, superfluids, etc. Here, we provide a unified picture of this fundamental problem that includes i) detuning of the free energies, ii) different self-interaction strengths and iii) finite lifetime of the modes. At such, this is particularly relevant for the dynamics of polaritons, both for their internal dynamics between their light and matter constituents, as well as for the more conventional dynamics of two spatially separated condensates. Polaritons are short-lived, interact on…

极化激元多端约瑟夫森结中的外尔奇点

Weyl singularities in polaritonic multi-terminal Josephson junctions

本文理论研究了腔激子-极化激元形成的5端约瑟夫森结，在4维参数空间中发现外尔点，并建立实空间涡旋与参数空间拓扑的联系，为直接测量拓扑相提供新平台。

Second order Josephson effect in excitonic insulators

We show that in electron-hole bilayers with excitonic order arising from conduction and valence bands formed by atomic orbitals that have different parities, nonzero interlayer tunneling leads to a second order Josephson effect. This means the interlayer electrical current is related to the phase of the excitonic order parameter as $J = J_c \sin2θ$ instead of $J = J_c \sin θ$, and that the system has two degenerate ground states at $θ=0, π$ that can be switched by an interlayer voltage pulse. When generalized to a three dimensional stack of alternating electron-hole planes or a two dimensional…

Pump driven normal-to-excitonic insulator transition: Josephson oscillations and signatures of BEC-BCS crossover in time-resolved ARPES

We consider a ground-state wide-gap band insulator turning into a nonequilibrium excitonic insulator (NEQ-EI) upon visiting properly selected and physically relevant highly excited states. The NEQ-EI phase, characterized by self-sustained oscillations of the complex order parameter, neatly follows from a Nonequilibrium Green's Function treatment on the Konstantinov-Perel' contour. We present the first {\em ab initio} band structure of LiF, a ground-state bulk insulator, in different NEQ-EI states and show that these states can be generated by currently available pump pulses. We highlight two g…

通过泵浦纠缠光子对生成纠缠极化子凝聚体

Generating entangled polaritonic condensates by pumping with entangled pairs of photons

该研究通过纠缠光子对泵浦生成纠缠极化子凝聚体，并分析了其稳态特性及纠缠寿命。

Long range correlations in a 97% excitonic one-dimensional polariton condensate

We report on the realization of an out-of-equilibrium polariton condensate under pulsed excitation in a one-dimensional geometry. We observe macroscopic occupation of a polaritonic mode with only 3% photonic fraction, and a nature strikingly close to that of a bare exciton condensate. With the help of this tiny photonic fraction, the condensate is found to display first-order coherence over distances as large as 10 microns. Based on a driven-dissipative mean field model, we find that the correlations length is limited by the effects of a shallow disorder under non-equilibrium conditions.