Supersolidity in two-component dipolar condensates

When cooled to very low temperatures, seemingly mundane materials may undergo transitions to exotic quantum phases of matter. Early examples include superconductors, which can conduct electric currents with zero resistance, as well as superfluid helium that can flow with zero viscosity. More recently, dilute vapours of metal atoms were cooled to ultracold temperatures to confirm a pristine realisation of the long-predicted Bose-Einstein condensate, a kind of superfluid gas where the atoms coalesce into a giant matter wave. Nowadays, it is routinely possible to trap and cool dilute gases down to nanokelvin temperatures, opening a window directly into the quantum world, with quantum effects manifesting on macroscopic length scales that can be literally observed with a camera. Termed quantum gases, such systems provide platforms with abundant versatility and high levels of control, facilitating the creation and exploration of novel phases of matter with potential applications for future quantum technologies. From a theoretical perspective, quantum gases are special because their diluteness means that theories can be developed from first principles and then tested in the lab. A few years ago, quantum gases were used to realise something called a supersolid phase, which was first proposed more than 50 years ago. The reason for the name is that such states of matter simultaneously exhibit properties of solids while also being a superfluid. One of the key ingredients that make supersolidity possible is that the underlying quantum gas can be comprised of dipolar atoms, with each atom behaving like a tiny bar magnet, and the resulting long-ranged and anisotropic inter-atomic interactions produces important analogues to traditional condensed matter systems. This results in solid-like and liquid-like properties, even though the underlying substance is still an ultra-dilute gas. This project aims to theoretically and computationally explore novel supersolid phases by combining two different quantum gases with imbalanced dipole strengths, that is, one of the components has atoms with a larger dipole moment than the other component. The numerous degrees of freedom and sources of interactions provided by two-component dipolar systems promise a remarkably rich array of physical phenomena that remains largely unexplored. We predict that by having two dipolar components, supersolids can be stabilised by a fundamentally different mechanism compared to the current generation of supersolids. In addition to exploring new physics, we expect that this will be an important step towards producing the first bulk supersolids, necessary to disentangle the bulk properties from finite-size effects.