Excitation spectrum of a double supersolid in a trapped dipolar Bose mixture

TL;DR

This paper investigates the excitation spectrum of a double supersolid formed by a trapped dipolar Bose mixture, revealing key experimental signatures and complex mode behaviors that characterize the coexistence of two superfluids.

Contribution

It provides a detailed analysis of the excitation spectrum of a double supersolid in dipolar Bose mixtures, highlighting observable modes and their relation to superfluid properties.

Findings

Doublet of superfluid compressional modes signals the double supersolid regime

Dipolar rotons and Higgs excitations exhibit non-trivial spin nature

Monitoring low-lying modes reveals transition of one component into droplet regime

Abstract

Dipolar Bose-Einstein condensates are excellent platforms for studying supersolidity, characterized by coexisting density modulation and superfluidity. The realization of dipolar mixtures opens intriguing new scenarios, most remarkably the possibility of realizing a double supersolid, composed by two interacting superfluids. We analyze the complex excitation spectrum of a miscible trapped dipolar Bose mixture, showing that it provides key insights about the double supersolid regime. We show that this regime may be readily probed experimentally by monitoring the appearance of a doublet of superfluid compressional modes, linked to the different superfluid character of each component. Additionally, the dipolar supersolid mixture exhibits a non-trivial spin nature of the dipolar rotons, the Higgs excitation, and the low-lying Goldstone modes. Interestingly, the analysis of the lowest-lying modes allows for monitoring the transition of just one of the components into the incoherent droplet regime, whereas the other remains coherent, highlighting their disparate superfluid properties.