A New Spin on Superconductivity

Max Hays, Valla Fatemi, Daniël Bouman +9 more

Superconducting spin qubit To date, the most promising solid-state approaches for developing quantum information-processing systems have been based on the circulating supercurrents of superconducting circuits and manipulating the spin properties of electrons in semiconductor quantum dots. Hays et al. combined the desirable aspects of both approaches, the scalability of the superconducting circuits and the compact footprint of the quantum dots, to design and fabricate a superconducting spin qubit (see the Perspective by Wendin and Shumeiko). This so-called Andreev spin qubit provides the opportunity to develop a new quantum information processing platform. Science , abf0345, this issue p. 430 ; see also abk0929, p. 390

James F. Annett, S. P. Kruchinin

George Kastrinakis

In a previous report (arxiv:0901.2487), we introduced a new fermionic variational wavefunction, suitable for interacting multi-species systems and sustaining superfluidity. This wavefunction contains a new quantum index of ghostly character, which does not appear in any observable quantity. Here we introduce a spin triplet version of this wavefunction, with parallel spin pairs only. Moreover, we present numerical solutions for the spin singlet superconducting state previously introduced.

J. R. Schrieffer

Valentin Crépel, Liang Fu

reaching about 10% of the Fermi temperature. Our work demonstrates a powerful method for studying strong coupling superconductivity with unconventional pairing symmetry. It also offers a realistic new route to realizing finite angular momentum superfluidity of spin-polarized fermions in optical lattice.