Time | Speaker | Title | Resources | |
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09:20 to 10:00 | Michiel Wouters (University of Antwerp, Belgium) |
Vortices in polariton and photon condensates In this talk, I will discuss the properties of quantized vortices in nonequilibrium polariton and photon condensates and how they differ from their equilibrium quantum fluid counterparts. |
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10:00 to 10:40 | Dario Ballarini (CNR NANOTEC – Lecce, Italia) |
Turbulent dynamics of 2D exciton-polariton quantum fluids Exciton-polaritons, resulting from the strong coupling of photons and excitons in semiconductor microcavities, have demonstrated their potential for exploring quantum fluids in optical systems over the past two decades. This study presents the initial evidence of turbulent dynamics and vortex clustering within 2D exciton-polariton fluids, focusing on the statistical properties of velocity and vorticity fields. By directly measuring the phase of the polariton fluid, we can identify and categorize vortices, revealing the emergence of an inverse energy cascade. Simultaneously, this measurement facilitates the extraction of complete statistics regarding the velocity field, establishing connections with classical turbulence and the universal behavior of critical systems. |
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10:40 to 11:10 | Nina Voronova (National Research Nuclear University, Russia) |
Exciton-polariton ring-shaped Josephson junction We present the first to our knowledge bosonic current-biased ring Josephson junction realised in a system of exciton-polaritons. We show that the weak link created by means of incoherent optical beam in such a ring may work in two distinct regimes in which the phase of the order parameter either smoothly reconnects between the two sides of the barrier, creating zero or non-zero winding around the ring, or experiences stochastic jumps resulting in statistics of different windings created within a given experimental setting. Drawing comparisons with superconducting rings interrupted by one Josephson junction, we provide a simple toy-model theory in terms of the 'washboard' energy landscape that explains the appearance of these two regimes. Studying the under-barrier supercurrent depending on the applied flow, we reveal a sinusoidal relation characteristic for Josephson physics. Analogies with a current-biased quantum interference devices (SQUIDs), such as the appearance of Shapiro-like steps, are discussed. |
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11:40 to 12:20 | Mathieu Gibert (Institut Neel CNRS, France) |
Direct visualization of the quantum vortex lattice structure, oscillations, and destabilization in rotating 4He Quantum vortices are a core element of superfluid dynamics and elusively hold the keys to our understanding of energy dissipation in these systems. We show that we can visualize these vortices in the canonical and higher-symmetry case of a stationary rotating superfluid bucket. Using direct visualization, we quantitatively verify Feynman’s rule linking the resulting quantum vortex density to the imposed rotational speed. We make the most of this stable configuration by applying an alternative heat flux aligned with the axis of rotation. Moderate amplitudes led to the observation of collective wave mode propagating along the vortices, and high amplitudes led to quantum vortex interactions. When increasing the heat flux, this ensemble of regimes defines a path toward quantum turbulence in rotating 4He and sets a baseline to consolidate the descriptions of all quantum fluids. REF: https://doi.org/10.1126/sciadv.adh2899 |
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12:20 to 12:50 | Vishwanath Shukla (IIT Kharagpur, India) | TBA | ||

14:30 to 15:00 | Rama Govindarajan (ICTS, India) |
The strange behaviour of inertial particles near co-rotating vortices This talk will be in the classical limit. Inertial particles are thought to evacuate the neighborhood of vortices and collect in strain regions. We will discuss how, in rotating flow, the simplest of which is just a co-rotating vortex pair, particles can remain for long periods in the neighborhood, display extreme clustering and bifurcations from fixed points to limit cycles to chaos. |
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15:00 to 15:30 | Luiza Angheluta [ONLINE] (University of Oslo, Norway) |
Vortex nucleation and dynamics in stirred Bose-Einstein condensates Quantum vortices, carriers of quantised vorticity, induce superfluid turbulence through collective dynamics. Turbulent fluctuations can also generate phonons, which mediate dipole nucleation and annihilation events. |
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15:30 to 16:00 | Takeshi Matsumoto (Kyoto University, Japan) |
Classical turbulence in two-dimensional lid-driven cavity We numerically study a turbulent flow of a classical incompressible fluid in a two-dimensional, so-called, lid-driven cavity. The cavity here is square and the top side (lid) moves with a prescribed horizontal velocity. Other three sides stay still (zero velocity). The boundary condition is no-slip. It is known that, at a moderate Reynolds number such as $Re=1000$, the lid-driven cavity flow is stationary. It is a nontrivial nonlinear stationary solution of the incompressible Navier--Stokes equations. These stationary solutions have been used as benchmarks for various numerical methods. |
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17:30 to 18:00 | Nir Navon [ONLINE] (Yale University, New Haven, CT) |
Many-body physics with ultracold fermions in an optical box For the past two decades harmonically trapped ultracold atomic gases have been used with great success to study fundamental many-body physics in flexible experimental settings. However, the resulting gas density inhomogeneity in those traps makes it challenging to study paradigmatic uniform-system physics (such as critical behavior near phase transitions) or complex quantum dynamics. [1] N. Navon, R.P. Smith, Z. Hadzibabic, Nature Phys. 17, 1334 (2021) |