New Chiral Phases of Superfluid 3He Stabilized by Anisotropic Silica Aerogel

A rich variety of Fermi systems condense by forming bound pairs, including high temperature [1] and heavy fermion [2] superconductors, Sr2RuO4 [3], cold atomic gases [4], and superfluid 3He [5]. Some of these form exotic quantum states having non-zero orbital angular momentum. We have discovered, in the case of 3He, that anisotropic disorder, engineered from highly porous silica aerogel, stabilizes a chiral superfluid state that otherwise would not exist. Additionally, we find that the chiral axis of this state can be uniquely oriented with the application of a magnetic field perpendicular to the aerogel anisotropy axis. At suffciently low temperature we observe a sharp transition from a uniformly oriented chiral state to a disordered structure consistent with locally ordered domains, contrary to expectations for a superfluid glass phase [6].Comment: 6 pages, 4 figure, and Supplementary Informatio

Bose-Einstein Condensation in Magnetic Insulators

The elementary excitations in antiferromagnets are magnons, quasiparticles with integer spin and Bose statistics. In an experiment their density is controlled efficiently by an applied magnetic field and can be made finite to cause the formation of a Bose-Einstein condensate (BEC). Studies of magnon condensation in a growing number of magnetic materials provide a unique window into an exciting world of quantum phase transitions (QPT) and exotic quantum states.Comment: 17 pages, 3 figure

Superfluid He-3 simulation of cosmic string creation in the early universe

We discuss the first experimental observations of a deficit in the thermal energy released after the exothermic neutron-He-3 nuclear reaction in superfluid He-3 at temperatures approaching 100 mu K. We propose that this deficit is associated with the creation of a vortex tangle as the liquid He-3 recrosses the superfluid transition. This process has many similarities with the theory of cosmic string creation during the GUT and electro weak transitions shortly after the Big Bang. Our measurements constitute the first quantitative test of defect creation via the cosmological Kibble mechanism for gauge symmetry breaking phase transitions and agree very well with the predictions of Zurek's scenario

Potential dark matter detector?:the detection of low energy neutrons by superfluid 3He

Using an existing experiment we have demonstrated in a pilot study that superfluid He-3 at 100 mu K can be used as a nuclear recoil detector sensitive to neutron and gamma interactions depositing energies down to a few hundred eV. The deposited energy is converted to He-3 quasiparticles which are detected by their damping effect on a vibrating wire resonator in the liquid. The system can be calibrated independently but a convenient fixed point is provided by the exothermic reaction n + He-3(2) = p + H-3(1) + 764 keV. Given the great potential for improvement we propose that the system might make a sensitive weakly interacting massive particle detector