Abstract
My contribution to this collection of articles in honor of David Lee and John Reppy on their 90th birthdays is a reflection on the remarkable phenomenology of the excitation spectra of superfluid 3He, in particular the B-phase which was identified by NMR and acoustic spectroscopy as the Balian–Werthamer state shown in 1963 to be the ground state of a spin-triplet, p-wave superconductor within weak-coupling BCS theory. The superfluid phases of 3He provide paradigms for electronic superconductors with broken space-time symmetries and non-trivial ground-state topology. Indeed, broken spin- and orbital rotation symmetries lead to a rich spectrum of collective modes of the order parameter that can be detected using NMR, acoustic and microwave spectroscopies. The topology of the BW state implies its low-temperature, low-energy transport properties are dominated by gapless Majorana modes confined on boundaries or interfaces. Given the central role the BW state played I discuss the acoustic and electromagnetic signatures of the BW state, the latter being relevant if an electronic analog of superfluid 3He-B is realized.
Original language | English (US) |
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Pages (from-to) | 87-118 |
Number of pages | 32 |
Journal | Journal of Low Temperature Physics |
Volume | 208 |
Issue number | 1-2 |
DOIs | |
State | Published - Jul 2022 |
Keywords
- Anderson–Higgs mechanism
- Bulk-edge correspondence
- Collective modes
- Higgs Boson
- Majorana modes
- Nambu–Goldstone modes
- Spontaneous symmetry breaking
- Superfluid He
- Topological superconductor
- Unconventional superconductivity
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- General Materials Science
- Condensed Matter Physics