Heidelberg Team Finds Competing Orders in Dipolar Quantum Gas

A new method exists to study exotic quantum materials named supersolids by generating both triangular and stripe patterns within a gas of highly magnetic atoms. The team confined these atoms using a specially shaped trap resembling a surfboard and precisely adjusted interaction strengths alongside dipole orientation to achieve this control; importantly, each structure exhibits properties of phase coherence and insulation. Control over competing patterns within a supersolid has been achieved; this exotic quantum state combines properties of crystalline solids and flowing superfluids.

Triangular and stripe arrangements are generated inside a gas of highly magnetic atoms held by a uniquely shaped trap with carefully adjusted atomic interactions creating these structures. Competing patterns have been fully generated within an exotic quantum state known as a supersolid; the unusual material behaves like both a solid crystal and a flowing superfluid simultaneously.

Tiny magnets arranged in a crystal pattern that also flow like a liquid illustrate how dipolar supersolids defy conventional expectations for solids which typically do not flow. To quantify order within these materials, researchers employed what is called a structural order parameter; similar to assessing whether a flock of birds is flying in formation or scattering randomly, it measures the degree of arrangement among the atoms.

Surfboard trap geometries enable independent tuning of dipolar interactions and atomic arrangements

The surfboard-shaped trap was central to observing subtle phases; its unique geometry confined the dipolar quantum gas while allowing precise control over atomic arrangement. Unlike conventional box or harmonic traps imposing symmetry restrictions, a custom design enabled independent tuning of interactions and dipole orientation, effectively ‘sculpting’ the potential experienced by each atom. Atoms organised themselves spatially within the material due to tailored confinement similarly to ripples on water forming equilateral triangles or parallel lines.

Spatial control proved key for stabilising both triangular and stripe density-modulated states which would otherwise be difficult to isolate experimentally. Approximately 150,000 atoms were utilised in these experiments at a temperature of 60 nanokelvins; ground state simulations using grid sizes up to 48x 24 micrometres closely matched these parameters. This approach enabled observation of patterns formed through tailored confinement, transitions between them, offering a flexible platform for investigating complex supersolid phases, and providing insight into how interaction strength influences atomic behaviour.

Observation of competing triangular and striped supersolid phases in dipolar gases

Researchers at Universität Heidelberg and colleagues have demonstrated control over structural order in dipolar gases, achieving an unprecedented level of precision evidenced by the observation of competing phases with a structural order parameter of 1.4 ±0.1 × 10⁵ atoms, a sharp increase compared to previous one-dimensional studies limited to single arrangements. The surfboard trap design proved key for independently tuning these parameters, allowing stabilisation of multiple spatial configurations exhibiting supersolid behaviour.

Both triangular and stripe phases were identified within this exotic state of matter known as a supersolid, alongside transitions between them achieved by tuning interaction strength and dipole orientation in a quantum gas of highly magnetic atoms.

Competing structural arrangements confirm long-held theoretical predictions in a novel supersolid phase

Creating both triangular and stripe patterns within the supersolid material addresses a longstanding need to experimentally verify predictions about how complex arrangements interact; theoretical models have long suggested such competition exists but proving it has been challenging until now. Further investigation into underlying mechanisms driving atomic behaviour is required to fully understand why transitions occur between phases. Specifically detailing whether interactions are primarily first or second order remains an open question. Despite uncertainties regarding transition orders, this represents strong progress for understanding supersolids, exotic materials balancing crystalline structure with fluid-like flow at extremely low temperatures. This extends beyond observing static structures by demonstrating transitions between distinct configurations, triangular and striped, crucially revealing that each can exhibit either superfluid flow or insulating behaviour depending on experimental conditions. This highlights the interplay of structural arrangement and quantum properties within these systems; a ‘structural order parameter’ quantified atomic alignment, revealing enhanced non-Gaussian fluctuations marking critical behaviour during phase transitions.

The researchers successfully created both triangular and stripe patterns within a supersolid material, confirming theoretical predictions about competing arrangements in this unusual state of matter. Observing these different spatial configurations, and the transitions between them, advances understanding of how crystalline structure coexists with fluid-like flow at extremely low temperatures. Quantifying atomic alignment using a structural order parameter of 1.4 ±0.1 × 10⁵ atoms revealed that each arrangement can exhibit either superfluidity or insulating properties depending on experimental conditions. The authors suggest further work is needed to fully characterise the nature of the phase transitions observed.

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