Sub-unity superfluid fraction of a supersolid from self-induced Josephson effect

Abstract

Recently, a new category of superfluids and superconductors has been discovered in various systems. These could be linked to the idea of a supersolid phase, featuring a macroscopic wavefunction with spatial modulation resulting from simultaneous, spontaneous breaking of gauge and translational symmetries. However, this relation has only been recognized in some cases and there is the need for universal properties quantifying the differences between supersolids and ordinary superfluids/superconductors or crystals. A key property is the superfluid fraction, which measures the reduction in superfluid stiffness due to spatial modulation, leading to the non-standard superfluid dynamics of supersolids. Here we employ the Josephson effect, common in superfluids and superconductors, to measure the superfluid fraction in a supersolid. Even without a physical barrier, the Josephson effect arises spontaneously in a supersolid due to spatial modulation. Individual lattice cells act as self-induced Josephson junctions, allowing the direct determination of the local superfluid fraction. We studied a cold-atom dipolar supersolid, revealing a significant sub-unity superfluid fraction. Our results open new research directions, enabling the exploration of novel phenomena like partially quantized vortices and supercurrents, potentially unifying the understanding of supersolid-like systems, and introducing a new type of Josephson junction.

15 pages, 10 figures

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Cited by in corpus (32)

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• Probing supersolidity through excitations in a spin-orbit-coupled Bose-Einstein condensate
• Superfluid fraction in the crystalline crust of a neutron star: role of BCS pairing
• Supersolid spectroscopy
• Honeycomb supersolid -- Dirac points and shear-instability induced crystal transitions
• Superfluid fraction of interacting bosonic gases
• Josephson dynamics and localization revivals in ultradilute quantum liquids
• Anomalous dispersion of shear waves in dipolar supersolids
• Signatures of rigidity and second sound in dipolar supersolids
• Assessing small accelerations using a bosonic Josephson junction
• Josephson vortices and persistent current in a double-ring supersolid system
• Rotation quenches in trapped bosonic systems
• Quantum action of the Josephson dynamics
• Moiré Superradiance in Cavity Quantum Electrodynamics with Quantum Atom Gas
• Single-fluid model for rotating annular supersolids and its experimental implications
• Beyond-mean-field phases of rotating dipolar condensates
• Bose-Einstein condensation of five $\alpha$ clusters in ${}^{20}$Ne and supersolidity
• Probing Superfluidity with Quantum Vortex Necklaces
• Band-edge superfluid of Bose-Einstein condensates in the spin-orbit-coupled Zeeman lattice
• Superfluid Fraction of a 2D Bose-Einstein Condensate in a Triangular Lattice
• Increasing the stability of a superfluid in a rotating necklace potential
• Strongly dipolar molecular Bose-Einstein condensates: From few- to many-body physics
• Optical response of the supersolid polaron
• Josephson oscillations of two weakly coupled Bose-Einstein condensates
• On the Novel Superfluidity in the Second Layer of ${}^4$He on Graphite
• Vorticity-Crystalline Order Coupling in Supersolids: Excitations and Re-entrant Phases
• Excitations and anisotropic sound in planar dipolar supersolids with tilted dipoles
• Vortex dynamics in rotating dipolar supersolids across Josephson and self-trapping regimes
• Bi-Josephson Effect in a Driven-Dissipative Supersolid
• Dynamical signatures of superfluidity and shear rigidity in different phases of a dipolar Bose-Einstein condensate