Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1705.10169 · Physical Review A

Time-reversal-invariant topological superfluids in Bose-Fermi mixtures

Jonatan Melkær Midtgaard, Zhigang Wu, Georg M. Bruun

Published Sep 5, 2017• 19 citations
arXivHTMLPDF

Abstract

A mixed dimensional system of fermions in two layers immersed in a Bose-Einstein condensate (BEC) is shown to be a promising setup to realize topological superfluids with time-reversal symmetry (TRS). The induced interaction between the fermions mediated by the BEC gives rise to a competition between $p$-wave pairing within each layer and $s$-wave pairing between the layers. When the layers are far apart, intralayer pairing dominates and the system forms a topological superfluid either with or without TRS. With decreasing layer separation or increasing BEC coherence length, interlayer pairing sets in. We show that this leads either to a second-order transition breaking TRS where the edge modes gradually become gapped or to a first-order transition to a topologically trivial $s$-wave superfluid. Our results provide a realistic road map for experimentally realizing a topological superfluid with TRS in a cold atomic system.

DOI
10.1103/physreva.96.033605

Related papers

Time-reversal-invariant spin-orbit-coupled bilayer Bose-Einstein condensates

Matthew Maisberger, Lincheng Wang, Kuei Sun +2 more

Time-reversal invariance plays a crucial role for many exotic quantum phases, particularly for topologically nontrivial states, in spin-orbit coupled electronic systems. Recently realized spin-orbit coupled cold-atom systems, however, lack the time-reversal symmetry due to the inevitable presence of an effective transverse Zeeman field. We address this issue by analyzing a realistic scheme to preserve time-reversal symmetry in spin-orbit-coupled ultracold atoms, with the use of Hermite-Gaussian-laser-induced Raman transitions that preserve spin-layer time-reversal symmetry. We find that the system's quantum states form Kramers pairs, resulting in symmetry-protected gap closing of the lowest two bands at arbitrarily large Raman coupling. We also show that Bose gases in this setup exhibit interaction-induced layer-stripe and uniform phases as well as intriguing spin-layer symmetry and spin-layer correlation.

arXiv:1710.08323•Physical Review A•May 29, 2018•2 citations

Two-dimensional paired topological superfluids of Rydberg Fermi gases

Ching-Yu Huang, Jiapei Zhuang, Po-Yao Chang +1 more

We systematically investigate the topological properties of spin polarized Rydberg-dressed fermionic atoms loaded in a bilayer optical lattice. Through tuning the Rydberg coupling strength and the interlayer tunneling amplitude, we identify different types of topological superfluid states generated from the interlayer pairing and relative pairing phase modulation of the coupled two-dimensional $p$-wave superfluids. These phases include gapped/gapless with/without time-reversal symmetry. One of the most interesting states is a gapless paired topological superfluid with both the time-reversal symmetry and particle-hole symmetry, which is a realization of a DIII gapless topological superconductor. The flexibility of experimental manipulation in such Rydberg-dressed fermionic systems therefore becomes a promising system for realizing interesting topological superfluids.

arXiv:2112.14027•Physical review. B./Physical review. B•Jul 6, 2022•4 citations

Emergent force in a bilayer superfluid Bose-Fermi mixture

Mehmet Günay

We investigate a system of two-atomic species in mixed dimensions, in which one species is spread in a three-dimensional space and the other species is confined in two parallel layers. The presence of atoms in 3-dimensions creates an induced potential for the ones confined in layers. Depending on the effective scattering length and the layer separation, the formation of p-wave pairing within the same layer or s-wave pairing between different layers has been suggested. It is shown that these pairs cannot coexist when time-reversal symmetry (TRS) is on, and there appears a transition from p-wave to s-wave as the ratio of the layer separation and the effective scattering length decreases. With the formation of the inter-layer pairing, we find an emergent force to be present at the critical point and show that it can be derived from the thermodynamic potential. This result offers a tool for experimentally realizing such transitions, and can find notable potential in the field of quantum-thermodynamics.

arXiv:1912.04598•Dec 10, 2019•0 citations

Topological superfluidity of lattice fermions inside a Bose-Einstein condensate

Jonatan Melkær Midtgaard, Zhigang Wu, Georg M. Bruun

We calculate the phase diagram of identical fermions in a two-dimensional lattice immersed in a three-dimensional Bose-Einstein condensate (BEC). The fermions exchange density fluctuations in the BEC, which gives rise to an attractive induced interaction. The resulting zero-temperature phase diagram exhibits topological ${p}_{x}+i{p}_{y}$ superfluid phases as well as a phase separation region. We show how to use the flexibility of the Bose-Fermi mixture to tune the induced interaction, so that it maximizes the pairing between nearest-neighbor sites, whereas phase separation originating from long-range interactions is suppressed. Finally, we calculate the Berezinskii-Kosterlitz-Thouless critical temperature of the topological superfluid in the lattice and discuss experimental realizations.

arXiv:1610.03352•Physical Review A•Dec 22, 2016•20 citations

Topological Superfluid in a Fermi-Bose Mixture with a High Critical Temperature

Zhigang Wu, Georg M. Bruun

We show that a 2D spin-polarized Fermi gas immersed in a 3D Bose-Einstein condensate constitutes a very promising system for realizing a p_{x}+ip_{y} superfluid. The fermions attract each other via an induced interaction mediated by the bosons, and the resulting pairing is analyzed with retardation effects fully taken into account. This is further combined with Berezinskii-Kosterlitz-Thouless (BKT) theory to obtain reliable results for the superfluid critical temperature. We show that both the strength and the range of the induced interaction can be tuned experimentally, which can be used to make the critical temperature approach the maximum value allowed by general BKT theory. Moreover, this is achieved while keeping the Fermi-Bose interaction weak so that three-body losses are small. Our results show that realizing a topological superfluid with atomic Fermi-Bose mixtures is within experimental reach.

arXiv:1609.09138•Physical Review Letters•Dec 9, 2016•55 citations

Mirror-symmetry-protected topological superfluid and second-order topological superfluid in bilayer fermionic gases with spin-orbit coupling

Beibing Huang, Gaixia Luo, Ning Xu

The experimental realizations of spin-orbit coupling (SOC) in cold atom gases put topological superfluids (TSs) under the spotlight. The topological protection of suggested superfluid models comes from the local antiunitary symmetries of ten Altland-Zirnbauer symmetry classes. In this paper we theoretically study a two-dimensional BDI model describing spin-orbit-coupled bilayer fermionic gases with $s$-wave interaction to realize mirror-symmetry- (nonlocal and unitary) protected gapped TS, beyond the paradigms suggested before. This gapped phase not only shows linearly dispersive Majorana zero modes on mirror invariant one-dimensional boundaries, but also shows Majorana corner states to realize the second-order TS (TS2) with $s$-wave pairing, which is explicitly different from the nonconventional pairings in the suggested systems to realize TS2. Generally, engineering the single-particle band structures should be easier than directly engineering the complicated pairings. Considering the tremendous progress in manipulating cold atom systems, our work provides a possible route (by engineering the single-particle physics, such as SOC) to realize mirror-symmetry-protected gapped TS and TS2 in cold fermionic systems in the future.

Physical Review A•Aug 2, 2019•7 citations
A mixed dimensional system of fermions in two layers immersed in a Bose-Einstein condensate (BEC) is shown to be a promising setup to realize topological superfluids with time-reversal symmetry (TRS). The induced interaction between the fermions mediated by the BEC gives rise to a competition between ppp-wave pairing within each layer and sss-wave pairing between the layers. When the layers are far apart, intralayer pairing dominates and the system forms a topological superfluid either with or without TRS. With decreasing layer separation or increasing BEC coherence length, interlayer pairing sets in. We show that this leads either to a second-order transition breaking TRS where the edge modes gradually become gapped or to a first-order transition to a topologically trivial sss-wave superfluid. Our results provide a realistic road map for experimentally realizing a topological superfluid with TRS in a cold atomic system.
Time-reversal invariance plays a crucial role for many exotic quantum phases, particularly for topologically nontrivial states, in spin-orbit coupled electronic systems. Recently realized spin-orbit coupled cold-atom systems, however, lack the time-reversal symmetry due to the inevitable presence of an effective transverse Zeeman field. We address this issue by analyzing a realistic scheme to preserve time-reversal symmetry in spin-orbit-coupled ultracold atoms, with the use of Hermite-Gaussian-laser-induced Raman transitions that preserve spin-layer time-reversal symmetry. We find that the system's quantum states form Kramers pairs, resulting in symmetry-protected gap closing of the lowest two bands at arbitrarily large Raman coupling. We also show that Bose gases in this setup exhibit interaction-induced layer-stripe and uniform phases as well as intriguing spin-layer symmetry and spin-layer correlation.
We systematically investigate the topological properties of spin polarized Rydberg-dressed fermionic atoms loaded in a bilayer optical lattice. Through tuning the Rydberg coupling strength and the interlayer tunneling amplitude, we identify different types of topological superfluid states generated from the interlayer pairing and relative pairing phase modulation of the coupled two-dimensional ppp-wave superfluids. These phases include gapped/gapless with/without time-reversal symmetry. One of the most interesting states is a gapless paired topological superfluid with both the time-reversal symmetry and particle-hole symmetry, which is a realization of a DIII gapless topological superconductor. The flexibility of experimental manipulation in such Rydberg-dressed fermionic systems therefore becomes a promising system for realizing interesting topological superfluids.
We investigate a system of two-atomic species in mixed dimensions, in which one species is spread in a three-dimensional space and the other species is confined in two parallel layers. The presence of atoms in 3-dimensions creates an induced potential for the ones confined in layers. Depending on the effective scattering length and the layer separation, the formation of p-wave pairing within the same layer or s-wave pairing between different layers has been suggested. It is shown that these pairs cannot coexist when time-reversal symmetry (TRS) is on, and there appears a transition from p-wave to s-wave as the ratio of the layer separation and the effective scattering length decreases. With the formation of the inter-layer pairing, we find an emergent force to be present at the critical point and show that it can be derived from the thermodynamic potential. This result offers a tool for experimentally realizing such transitions, and can find notable potential in the field of quantum-thermodynamics.
We calculate the phase diagram of identical fermions in a two-dimensional lattice immersed in a three-dimensional Bose-Einstein condensate (BEC). The fermions exchange density fluctuations in the BEC, which gives rise to an attractive induced interaction. The resulting zero-temperature phase diagram exhibits topological px+ipy{p}_{x}+i{p}_{y}px​+ipy​ superfluid phases as well as a phase separation region. We show how to use the flexibility of the Bose-Fermi mixture to tune the induced interaction, so that it maximizes the pairing between nearest-neighbor sites, whereas phase separation originating from long-range interactions is suppressed. Finally, we calculate the Berezinskii-Kosterlitz-Thouless critical temperature of the topological superfluid in the lattice and discuss experimental realizations.
We show that a 2D spin-polarized Fermi gas immersed in a 3D Bose-Einstein condensate constitutes a very promising system for realizing a p_{x}+ip_{y} superfluid. The fermions attract each other via an induced interaction mediated by the bosons, and the resulting pairing is analyzed with retardation effects fully taken into account. This is further combined with Berezinskii-Kosterlitz-Thouless (BKT) theory to obtain reliable results for the superfluid critical temperature. We show that both the strength and the range of the induced interaction can be tuned experimentally, which can be used to make the critical temperature approach the maximum value allowed by general BKT theory. Moreover, this is achieved while keeping the Fermi-Bose interaction weak so that three-body losses are small. Our results show that realizing a topological superfluid with atomic Fermi-Bose mixtures is within experimental reach.
The experimental realizations of spin-orbit coupling (SOC) in cold atom gases put topological superfluids (TSs) under the spotlight. The topological protection of suggested superfluid models comes from the local antiunitary symmetries of ten Altland-Zirnbauer symmetry classes. In this paper we theoretically study a two-dimensional BDI model describing spin-orbit-coupled bilayer fermionic gases with sss-wave interaction to realize mirror-symmetry- (nonlocal and unitary) protected gapped TS, beyond the paradigms suggested before. This gapped phase not only shows linearly dispersive Majorana zero modes on mirror invariant one-dimensional boundaries, but also shows Majorana corner states to realize the second-order TS (TS2) with sss-wave pairing, which is explicitly different from the nonconventional pairings in the suggested systems to realize TS2. Generally, engineering the single-particle band structures should be easier than directly engineering the complicated pairings. Considering the tremendous progress in manipulating cold atom systems, our work provides a possible route (by engineering the single-particle physics, such as SOC) to realize mirror-symmetry-protected gapped TS and TS2 in cold fermionic systems in the future.