Chiral twodimensional p-wave superfluid from s-wave pairing in the BEC regime

Abstract

Twodimensional spin-orbit-coupled Fermi gases subject to s-wave pairing can be driven into a topological phase by increasing the Zeeman spin splitting beyond a critical value. In the topological phase, the system exhibits the hallmarks of chiral p-wave superfluidity, including exotic Majorana excitations. Previous theoretical studies of this realization of a twodimensional topological Fermi superfluid have focused on the BCS regime where the s-wave Cooper pairs are only weakly bound and, hence, the induced chiral p-wave order parameter has a small magnitude. Motivated by the goal to identify potential new ways for the experimental realization of robust topological superfluids in ultra-cold atom gases, we study the BCS-to-BEC crossover driven by increasing the Cooper-pair binding energy for this system. In particular, we obtain phase diagrams in the parameter space of two-particle bound-state energy and Zeeman spin-splitting energy. Ordinary characteristics of the BCS-to-BEC crossover, in particular the shrinking and eventual disappearance of the Fermi surface, are observed in the nontopological phase. In contrast, the topological phase retains all features of chiral p-wave superfluidity, including a well-defined underlying Fermi surface, even for large s-wave pair-binding energies. Compared to the BCS limit, the topological superfluid in the BEC regime turns out to be better realizable even for only moderate magnitude of spin-orbit coupling because the chiral p-wave order parameter is generally larger and remnants of s-wave pairing are suppressed. We identify optimal parameter ranges that can aid further experimental investigations and elucidate the underlying physical reason for the persistence of the chiral p-wave superfluid.

arXiv comment12 pages, 11 figures, RevTex4.1, v2: extended discussion and more results, to appear in PRA

References in corpus (54)

• Many-Body Physics with Ultracold Gases
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries, and the fractional quantum Hall effect
• A generic new platform for topological quantum computation using semiconductor heterostructures
• Non-abelian statistics of half-quantum vortices in p-wave superconductors
• Topological superconductors: a review
• Majorana fermions in a tunable semiconductor device
• Majorana Zero Modes and Topological Quantum Computation
• Spin-orbit coupling in quantum gases
• BCS-BEC Crossover: From High Temperature Superconductors to Ultracold Superfluids
• Degenerate Quantum Gases with Spin-Orbit Coupling
• Fermion zero modes on vortices in chiral superconductors
• Tuning spin-orbit coupling and superconductivity at the SrTiO3/LaAlO3 interface: a magneto-transport study
• $p_x+i{p}_y$ superfluid from s-wave interactions of fermionic cold atoms
• Chiral Superconductors
• Two-dimensional epitaxial superconductor-semiconductor heterostructures: A platform for topological superconducting networks
• BEC-BCS crossover in "magnetized" Feshbach-resonantly paired superfluids
• Phase separation in asymmetrical fermion superfluids
• Non-Abelian Topological Orders and Majorana Fermions in Spin-Singlet Superconductors
• Asymmetric Two-component Fermion Systems in Strong Coupling
• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Imbalanced Feshbach-resonant Fermi gases
• Finite temperature phase diagram of a polarised Fermi condensate
• BEC-BCS crossover, phase transitions and phase separation in polarized resonantly-paired superfluids
• BCS-BEC crossover in a two-dimensional Fermi gas
• Experimental observation of a topological band gap opening in ultracold Fermi gases with two-dimensional spin-orbit coupling
• Phase diagram of a cold polarized Fermi gas
• Momentum distribution and condensate fraction of a Fermi gas in the BCS-BEC crossover
• Zero modes of two-dimensional chiral p-wave superconductors
• An Index Theorem for the Majorana Zero Modes in Chiral P-Wave Superconductors
• Exact Numerical Results on the Ground State of Strongly Interacting Fermi Gases in Two Dimensions
• Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases
• Momentum distribution of a Fermi gas of atoms in the BCS-BEC crossover
• Topological superfluid in a trapped two-dimensional polarized Fermi gas with spin-orbit coupling
• Phase separation in a polarized Fermi gas with spin-orbit coupling
• Topological phase transitions in ultra-cold Fermi superfluids: the evolution from BCS to BEC under artificial spin-orbit fields
• Phase Diagram of Cold Polarized Fermi Gas in Two Dimensions
• Route to Topological Superconductivity via Magnetic Field Rotation
• Phase diagram of a polarized Fermi gas across a Feshbach resonance in a potential trap
• Fermi-to-Bose crossover in a trapped quasi-2D gas of fermionic atoms
• The $s$-wave scattering length of a Gaussian potential
• Composite bosons in the 2D BCS-BEC crossover from Gaussian fluctuations
• Can one determine the underlying Fermi surface in the superconducting state of strongly correlated superconductors?
• Superfluidity and collective modes in Rashba spin-orbit coupled Fermi gases
• Detecting the breached pair phase in a polarized ultracold Fermi gas
• Rashba spin-orbit coupling, strong interactions, and the BCS-BEC crossover in the ground state of the two-dimensional Fermi Gas
• Comment on "Superfluid stability in the BEC-BCS crossover"
• Stable Sarma State in Two-band Fermi Systems
• The BCS-BEC Crossover
• BCS-BEC crossover in a quasi-two-dimensional Fermi gas
• Spinodal decomposition in polarised Fermi superfluids
• Many Body Correlation Corrections to Superconducting Pairing in Two Dimensions.
• Accurate projective two-band description of topological superfluidity in spin-orbit-coupled Fermi gases
• Quantum fluctuations of a resonantly interacting $p$-wave Fermi superfluid in two dimensions

Cited by in corpus (5)

• Two types of dark solitons in a spin-orbit-coupled Fermi gas
• Coexistence of topological and nontopological Fermi-superfluid phases
• Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting
• Andreev bound states at boundaries of polarized 2D Fermi superfluids with s-wave pairing and spin-orbit coupling
• s- and p-superfluidity of Fermi atoms in Bose-Fermi mixtures