Multipolar condensates and multipolar Josephson effects

TL;DR

This paper demonstrates that dipole and higher-order multipolar condensates are generic in bosonic systems, leading to novel macroscopic quantum phenomena like multipolar Josephson effects and hierarchical condensate phases.

Contribution

It shows that dipole condensation is a generic phenomenon in bosonic systems due to self-proximity effects, enabling experimental control and the emergence of multipolar condensates.

Findings

Dipole condensates occur readily in bosonic systems due to self-proximity effects.

Dipolar Josephson effects can be realized without particle flow.

A hierarchy of multipolar condensates forms through kinetic processes.

Abstract

When single-particle dynamics are suppressed in certain strongly correlated systems, dipoles arise as elementary carriers of quantum kinetics. These dipoles can further condense, providing physicists with a rich realm to study fracton phases of matter. Whereas recent theoretical discoveries have shown that an unconventional lattice model may host a dipole condensate as the ground state, fundamental questions arise as to whether dipole condensation is a generic phenomenon rather than a specific one unique to a particular model and what new quantum macroscopic phenomena a dipole condensate may bring us with. Here, we show that dipole condensates prevail in bosonic systems. Because of a self-proximity effect, where single-particle kinetics inevitably induces a finite order parameter of dipoles, dipole condensation readily occurs in conventional normal phases of bosons. Our findings allow experimentalists to manipulate the phase of a dipole condensate and deliver dipolar Josephson effects, where supercurrents of dipoles arise in the absence of particle flows. The self-proximity effects can also be utilized to produce a generic multipolar condensate. The kinetics of the $n$-th order multipoles unavoidably creates a condensate of the $(n+1)$-th order multipoles, forming a hierarchy of multipolar condensates that will offer physicists a whole new class of macroscopic quantum phenomena.