Until now, controlling quantum gases with long-range interactions presented significant challenges in understanding complex many-body phenomena. For the first time, researchers at Columbia University and Radboud University have observed electrostriction, an elliptical deformation, in a Bose-Einstein condensate comprised of dipolar molecules using microwave dressing to manipulate their interactions. This achievement demonstrates that the BEC can be torqued by dynamically changing an applied microwave field; importantly, modelling accurately matched experimental results up to dipolar lengths of 6,000 atomic units.

Scientists have demonstrated a new level of control over Bose-Einstein condensates, unique states of matter formed from ultra-cooled molecules; they achieved this through manipulation with microwaves. The team observed electrostriction, essentially an elliptical reshaping, within these molecular condensates by carefully tuning interactions using microwave fields. This ability to distort the condensate’s shape allows researchers to rotate it, potentially unlocking investigations into unusual quantum behaviours like superfluidity, flow without resistance, and supersolidity which combines properties of both solids and liquids.

The researchers and Radboud University have achieved unprecedented control over a Bose-Einstein condensate, a state of matter formed when atoms are cooled to near absolute zero, causing them to behave as one; it’s akin to how photons in a laser all act together. The researchers successfully modelled their experiments up to dipolar lengths of 6,000 atomic units, demonstrating accurate predictions about this behaviour. Understanding whether existing theoretical models adequately describe these uniquely dressed molecules is now crucial; can current frameworks capture the nuances introduced by manipulating interactions at this scale.

Polarization control sculpts molecular interactions within a dipolar Bose, Einstein condensate

Double microwave dressing proved central to the methodology; it employs two precisely tuned microwave fields, one polarized along a σ direction and another along π, to sculpt the interactions between molecules within the Bose, Einstein condensate (BEC). By carefully controlling polarization and strength, anisotropic dipolar interactions were manipulated: these directional forces arise from electrical charge distribution within each molecule. Scientists at Columbia University successfully created a dipolar molecular BEC, offering precise active control over interaction strength and anisotropy compared with alternative methods like magnetic stirring of atomic gases.

Microwave Control Extends Bose, Einstein Condensate Elongation to Six Thousand Atomic Units

An elliptical deformation, electrostriction, has been achieved within the BEC, demonstrating control up to dipolar lengths of 6,000 atomic units; this surpasses previous limitations struggling beyond approximately 1,000 atomic units. The team spanning Columbia University and Radboud University utilised the microwave technique described above to manipulate anisotropic dipolar interactions between molecules in the BEC. This manipulation enabled them to torque the molecular BEC by dynamically altering applied microwave field orientation, opening avenues for exploring quantum phenomena such as vorticity and superfluidity in strongly interacting systems.

Analysis revealed excellent agreement between experimental observations and theoretical models based on an extended Gross, Pitaevskii equation, validating predictions about interaction strengths at these scales. Measurements showed tunable dipolar lengths extending beyond 10,000 atomic units, a key result given typical interparticle spacings are around this value.

Modelling strongly interacting quantum gases reveals limitations in established theoretical approaches

Controlling quantum gases unlocks understanding of exotic states of matter; however, accurately modelling their behaviour remains a vital hurdle. The predictive power of the extended Gross, Pitaevskii equation successfully matched experimental results under weaker interactions but isn’t guaranteed as forces intensify within these condensates. Current theoretical frameworks present uncertainties when dealing with exceptionally strong dipolar interactions, specifically regarding potential inaccuracies introduced by discarding unstable modes during calculations. This controlled deformation of a Bose, Einstein condensate comprised of dipolar molecules represents an advance beyond previous control limits imposed on quantum gases utilising long-range molecular forces and opens possibilities for investigating complex many-body phenomena previously inaccessible experimentally. Researchers induced rotation within the condensate by dynamically altering applied microwave radiation, establishing a platform to explore exotic states such as superfluidity and supersolidity which combine properties of both liquids and solids.

The research team successfully demonstrated electrostriction in a Bose-Einstein condensate composed of dipolar molecules, inducing an elliptical shape through precisely controlled interactions using microwaves. This manipulation confirms that these molecular condensates can be rotated via dynamic changes to the microwave field orientation. The experimental results align well with models based on the extended Gross-Pitaevskii equation under weaker interaction strengths, validating current understanding of behaviour at this scale. Researchers intend to use this technique to investigate quantum phenomena like vorticity and superfluidity within strongly interacting matter.

👉 More information
🗞 Electrostriction in a Bose-Einstein Condensate of Dipolar Molecules
✍️ Haneul Kwak, Ian Stevenson, Weijun Yuan, Siwei Zhang, Asaf Toprakci, Lin Su, Tijs Karman and Sebastian Will
🧠 ArXiv: https://arxiv.org/abs/2608.19180

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