Matters are not so clear on the physical side

Axel Pérez-Obiol, Juan Polo, Luigi Amico A

Quantum phase slips are a dual process of particle tunneling in coherent networks.Besides being of central interest to condensed matter physics, quantum phase slips are resources that are sought to be manipulated in quantum circuits.Here, we devise a specific matter-wave circuit enlightening quantum phase slips.Specifically, we investigate the quantum many-body dynamics of two side-by-side ring-shaped neutral bosonic systems coupled through a weak link.By imparting a suitable magnetic flux, persistent currents flow in each ring with given winding numbers.We demonstrate that coherent phase slips occur as winding number transfer among the two rings, with the populations in each ring remaining nearly constant.Such a phenomenon occurs as a result of a specific entanglement of circulating states, that, as such, cannot be captured by a mean-field treatment of the system.Our work can be relevant for the observation of quantum phase slips in cold-atom experiments and their manipulation in matter-wave circuits.To make contact with the field, we show that the phenomenon has clear signatures in the momentum distribution of the system providing the time-of-flight image of the condensate.

Josh Roeloffs

James E Beecham

Slow-light experiments in sodium Bose-Einstein condensates demonstrate that electromagnetic group velocitycan be reduced by approximately seven orders of magnitude relative to light in vacuum. Separately, the sodiumatoms in the same class of coherent condensate environment exhibit an extraordinary matter-sidetransformation: thermal motion is reduced, momentum-space occupation narrows, phonon propagation is slow,independent particle trajectories are suppressed, and a macroscopic fraction of the atoms occupy a singlecoherent quantum state. The central purpose of this paper is to separate direct observation from interpretiveassumption. Conventional physics explains slow light through electromagnetically induced transparency andcoherent atom-light coupling, and it explains condensate matter dynamics through established quantum gastheory. The Space-Phase (SP3) hypothesis proposes a different interpretive possibility: that both energy-side andmatter-side reductions may reflect conditioning of a common Faraday-Maxwell medium. To compare thesedomains without assuming the correctness of either interpretation, this paper defines a dimensionless normalizedEffective Matter Dynamics Index Unit (EMDI-U). EMDI-U is computed on a logarithmic scale by comparingan effective matter-dynamics suppression index with the independently measured optical slowing factor. Using aconservative matter-side suppression range of approximately 10^6 to 10^8 and an optical slowing factor ofapproximately 1.8 x 10^7, the EMDI-U interval is approximately 0.83 to 1.10, with unity representing equalitywith the light-side reduction. The result does not prove SP3. It does, however, identify a striking quantitativeconvergence: when matter dynamics are evaluated as multidimensional dynamical freedom rather than onedimensional speed alone, the matter-side reduction and light-side slowing occupy the same range. Thisconvergence justifies a formal experimental program to test whether the two domains co-vary under controlledchanges in condensate conditioning.

Emilio Santos

Nathan Goldman, Tarik Yefsah

Ultracold gases in optical lattices provide control and tunability for the exploration of Weyl semimetal physics