This talk adresses the transport properties of superfluids like Helium II when taking into account the internal degrees of freedom of boundary solids. Indeed, superfluids have the special property of managing frictionless transport due to their absence of viscosity below a critical velocity. In such systems, the boundary solids are often described a simple boundary condition where the...
I will present recent results on two-dimensional systems: 2D polarized Fermi gases evolving from the polaronic limit to an FFLO instability and 2D mixtures of fermions and bosons. In the latter case I will discuss the fate of Fermi polarons obeying Bose statistics when their concentration gets finite.
We introduce the Single Vortex Box (SVB) – a nanodevice that allows to treat a single superconducting vortex as a macroscopic, yet quantized, “particle” that can be created and annihilated on demand using electrical current pulses[1]. By applying fast, nanosecond-resolving switching thermometry [2], we measure the temperature rise and the subsequent thermal relaxation resulting from the...
The dynamics of quantized vortices underlies many phenomena of different quantum systems, from superconductors to neutron stars, and represent a particularly hard problem to tackle in fermionic systems. In this talk I will report a series of experiments on vortex dynamics in strongly-interacting Fermi superfluids, highly controllable systems where the dynamic of vortices can be studied in a...
Holography or gauge/gravity duality provides a novel description of a strongly coupled superfluid via a gravitational theory in a higher-dimensional curved space-time with a black hole. Vortex dynamics in the holographic superfluid exhibits strong dissipation in the range of real-world superfluids. The talk gives an overview of various aspects of dissipative vortex dynamics and quantum...
Neutron stars are compact celestial objects that offer the unique opportunity to explore matter and its interactions under conditions that cannot be reproduced elsewhere in the Universe. Their extreme gravitational, rotational and magnetic energy reservoirs fuel their diverse emission properties, which are visible across the electromagnetic waveband as well as the gravitational wave window....
Superfluidity impacts the dynamics of rotating neutron stars. The presence of superfluids in neutron stars is an important ingredient in models of pulsar glitches, oscillation modes, cooling of old pulsars and, possibly, even timing noise. I will discuss how simulations of quantised vortices can help us to understand how superfluid momentum is transported in neutron stars, and their relevance...
In the inner crust of neutron stars, exotic nuclear clusters are probably arranged in a periodic lattice, and surrounded by a superfluid gas of unbound neutrons. The superfluid component of the crust is involved in some of the mechanisms to explain pulsar glitches. But, for the comparison with observations, one needs to know the neutron superfluid fraction. In order to compute it, the crucial...
Persistent currents are long-lived metastable states characterized by quantized circulation, denoted by the winding number w. The main topic of this talk is the investigation of the stability of these supercurrents in the presence of impurities and throughout the BEC-BCS crossover. For this purpose, we solve the Gross-Pitaevskii equation in the BEC regime and employ a time-dependent density...
In this talk I will discuss some results related to turbulence and interference motivated by cold-atom experiments here at WSU.
Neutron stars are the collapsed cores of massive stars that have undergone a supernova explosion. They are the densest known astrophysical objects, with a mass typically 1.4 times that of the Sun compressed into a radius of approximately 10 km. Deep within the star, where the density exceeds the nuclear equilibrium density, neutrons become superfluid and protons become superconducting. As a...
Fermionic p-wave superfluid 3He is known to host various kinds of quantized vortices, including half-, single- and double-quantum. Regular motion of such vortices through the fluid is well understood: It is governed by the mutual friction, which originates in interaction of vortex-core-bound fermions with bulk quasiparticles. I present three examples of less usual vortex dynamics observed...
Rotational glitches can result from the angular momentum exchange between the curst and neutron star interiors. We study the dynamics of about 600 quantum vortices in a spinning-down two-dimensional neutron superfluid using the Gross--Pitaevskii model. For the first time, we find convincing spatial-temporal evidence of avalanching behaviour with about 10-20 vortices in each event resulting...
We develop a time dependent effective theory based on the PLDA theory [1] for the ground state behaviour of the order parameter of fermions in the BCS-BEC crossover. Our approach is computationally efficient and paves the way to compare with elaborated experimental implementations. With our time dependent theory we study the stability of dark soliton [2,3] solutions at T=0 across the BCS-BEC...
Considering the initially immiscible configuration of homogeneous binary Bose-Einstein condensates confined in a two-dimensional circular box, I will report the results of some investigations we have carried out considering the emergence of Rayleigh-Taylor (RT) and Kelvin-Helmholtz (KH) instabilities.
Immiscible superfluid mixtures have been shown to display a wider variety of exotic dynamics than their single component counterparts. Here we consider the mean-field vortex solutions and their stability within a two-component Bose-Einstein condensate in the immiscible limit. We begin by systematically study the dynamics of a binary immiscible Bose-Einstein condensate in two dimensions, where...
We propose three distinct schemes for implementing local \textit{quantum friction} (QF) within the Hartree-Fock-Bogoliubov (HFB) approximation to efficiently dissipate energy in fermionic many-body systems. The first scheme introduces a local current-dependent potential in the Hamiltonian, the second incorporates an external pairing potential that conserves particle number, and the third...
Josephson junctions represent a powerful tool to probe macroscopic phase
coherence in different systems. They are also fundamental for atomtronics
circuits, thanks to their well defined current-chemical potential and current-phase. In our experimental system, we create atomic Josephson junctions using Fermi superfluids of lithium-6, realized by coupling two quasi-two-dimensional atomic...