Overview: Superfluid helium-three is a known topological quantum condensed system that that is a model for understanding more complex quantum materials, such as putative, odd-parity chiral superconductors; a subject of interest to researchers in the burgeoning field of quantum information science. The proposal, Quantum Coherent Applications of Superfluid 3He, is a platform for both basic research and instrumentation development. Using anisotropic aerogels in which the helium is imbibed, we can control the direction of the angular momentum in the superfluid state and test recent theory relevant to its application to topological superconductors. In a second application of quantum sensing, this proposal will develop a long-lived, quantum spin coherent state of superfluid 3He as a detector for light dark matter. This is a step forward in sensing sensitivity and its application will establish new limits on galactic axion production, an existential problem in modern physics. Undergraduate and high school students will develop aerogel growth protocols, a spin-off from the present NSF supported superfluid 3He program. These films are of technological importance promising applications to be realized in collaboration with the Facility for Rare Isotope Beams at Michigan State University to improve gas electron multiplier detectors. Intellectual Merit: The proposal, Quantum Coherent Applications of Superfluid 3He, will stabilize new types of helium-three superfluid phases exhibiting different spontaneously-broken symmetries by engineering anisotropy through confinement of the superfluid in highly porous, anisotropic, aerogels. Each superfluid phase has its specific type of orbital and/or spin topological singularities including vortices and superfluid textures that affect the quantization directions of orbital and spin angular momenta determined with nuclear magnetic resonance (NMR). A first project focuses on the superfluid A-phase, a chiral phase of interest to researchers in quantum information science. Chirality, in this context, is the combination of loss of mirror symmetry in conjunction with broken time reversal symmetry, a key property of topological superconductivity. In the proposal, anisotropic phases of superfluid helium-three are stabilized in globally-uniform positively-strained silica aerogel. Based on recent studies of superfluid 3He in anisotropic aerogel, it was found that the orbital quantization axis abruptly switches through 90° at a well-defined temperature dependent on pressure. This control can be harnessed as a quantum coherent sensing tool. The “flop” transition in positively strained aerogel will be used to switch the chiral axis and turn on/off the transverse thermal Hall effect, as according by recent theory. Testing this prediction will open up its application to putative chiral, odd-parity superconductors. A second project, builds on recent success in the PI’s laboratory; the capability to hold temperatures below 0.001 K for as long as one month at a time. These extremely efficient refrigerators allow maintenance of quantum coherence of nuclear spin precession measured with NMR. The homogeneous precession domain, lasts over time scales of many seconds in the superfluid 3He B-phase. It is proposed as a quantum sensing medium for dark matter detection, taking advantage of improvement in spin coherence after elimination of magnetic quasiparticle scattering from surfaces. The partnership from theoretical physicists in both the fields of superfluid 3He and dark matter, together with cryogenic achievements at No
|Effective start/end date
|7/1/22 → 6/30/25
- National Science Foundation (DMR-2210112 002)
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