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

Magnetic cooling of ultracold two-component fermions using high-spin Fermi gases

Carsten Klempt, Luis Santos, T. Vekua

Published Sep 14, 2010• 0 citations
OpenAlex

Abstract

Institut fu¨r Quantenoptik, Leibniz Universita¨t Hannover, 30167 Hannover, Germany(Dated: September 15, 2010)We propose a cooling scheme for two-component fermions in optical lattices that employs theinternal structure of high-spin Fermi gases. Adiabatically changing the quadratic Zeeman couplingfrom a uniform distribution to a space dependent one allows for the creation of an inner spin-1/2 coresurrounded by spin-S wings. We show that, due to frustration, spin-S regions act via spin-changingcollisions as effective entropy absorbers for the spin-1/2 core with increasing efficiency at lowertemperatures and higher dimensions. We illustrate our scheme explicitly on 1D spin-3/2 fermions,showing that the entropy of the spin-1/2 Mott region can be significantly reduced. Our findingssuggest that the proposed method can be highly efficient, opening a feasible path for accessinganti-ferromagnetic order under current experimental conditions.

Related papers

Adiabatic spin cooling using high-spin Fermi gases

Maria Colomé‐Tatché, Carsten Klempt, Luis Santos +1 more

Spatial entropy redistribution plays a key role in adiabatic cooling of ultra-cold lattice gases. We show that high-spin fermions with a spatially variable quadratic Zeeman coupling may allow for the creation of an inner spin-1/2 core surrounded by high-spin wings. The latter are always more entropic than the core at high temperatures and, remarkably, at all temperatures in the presence of frustration. Combining thermodynamic Bethe Ansatz with local density approximation, we study the spatial entropy distribution for the particular case of one-dimensional spin-3/2 lattice fermions in the Mott phase. Interestingly, this spatially dependent entropy opens a possible path for an adiabatic cooling technique that, in contrast to previous proposals, would specifically target the spin degree of freedom. We discuss a possible realization of this adiabatic cooling, which may allow for a highly efficient entropy decrease in the spin-1/2 core and help access antiferromagnetic order in experiments on ultracold spinor fermions.

arXiv:1009.2606•New Journal of Physics•Nov 17, 2011•7 citations

Cooling schemes for two-component fermions in layered optical lattices

Shimpei Goto, Ippei Danshita

Recently, a cooling scheme for ultracold atoms in a bilayer optical lattice has been proposed (A. Kantian et al., arXiv:1609.03579). In their scheme, the energy offset between the two layers is increased dynamically such that the entropy of one layer is transferred to the other layer. Using the full-Hilbert-space approach, we compute cooling dynamics subjected to the scheme in order to show that their scheme fails to cool down two-component fermions. We develop an alternative cooling scheme for two-component fermions, in which the spin-exchange interaction of one layer is significantly reduced. Using both full-Hilbert-space and matrix-product-state approaches, we find that our scheme can decrease the temperature of the other layer by roughly half.

arXiv:1710.00521•Physical Review A•Dec 1, 2017•9 citations

Getting into Shape: Efficient Cooling Scheme for Fermionic Atoms in Optical Lattices

Jean-Sébastien Bernier, Corinna Kollath, Antoine Georges +4 more

We propose an experimental procedure to cool fermionic atoms loaded into an optical lattice. The central idea is to spatially divide the system into entropy-rich and -poor regions by shaping the confining potential profile. Atoms in regions of high entropy per particle are subsequently isolated from the system. We discuss how to experimentally carry out this proposal, and perform a quantitative study of its efficiency. We find that the entropy per particle, $s$, can typically be reduced by a factor of 10 such that entropies lower than $s/k_B \sim 0.2$ can be reached. Cooling into highly sought-after quantum phases (such as an antiferromagnet) can thus be achieved. We show that this procedure is robust against variations of the experimental conditions.

arXiv:0902.0005•Feb 2, 2009•0 citations

Mott-Insulator Phases of Spin- 3/2 Fermions in the Presence of Quadratic Zeeman Coupling

Karen Rodríguez, Arturo Argüelles, Maria Colomé‐Tatché +2 more

We study the influence of the quadratic Zeeman effect on the Mott-insulator phases of hard-core 1D spin-3/2 fermions. We show that, contrary to spinor bosons, the quadratic Zeeman coupling preserves an SU(2)⊗SU(2) symmetry, leading for large-enough quadratic Zeeman coupling to an isotropic pseudo-spin-1/2 Heisenberg antiferromagnet. Decreasing the quadratic Zeeman coupling, this phase undergoes, depending on the scattering lengths, either a Kosterlitz-Thouless transition into a gapped dimerized phase or a commensurate-incommensurate transition into a gapless spin liquid. This rich phase diagram can be observed experimentally in four-component fermions in optical lattices under similar entropy constraints to those needed for Néel order in spin-1/2 gases.

arXiv:1002.0287•Physical Review Letters•Jul 27, 2010•22 citations

Orbital magnetism of ultracold fermionic gases in a lattice: Dynamical mean-field approach

Agnieszka Cichy, Andrii Sotnikov

We study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-metal-like atoms in optical lattices that can be effectively described by the two-band spin-$1/2$ Hubbard model including Hund's exchange coupling term. Our main goal is to investigate the effect of exchange interactions on finite-temperature magnetic phases for a wide range of lattice fillings. We use the dynamical mean-field theory approach and its real-space generalization to obtain finite-temperature phase diagrams including transitions to magnetically ordered phases. It allows to determine optimal experimental regimes for approaching long-range ferromagnetic ordering in ultracold gases. We also calculate the entropy in the vicinity of magnetically ordered phases, which provides quantitative predictions for ongoing and future experiments aiming at approaching and studying long-range ordered states in optical lattices.

arXiv:1602.08031•Physical Review A•May 23, 2016•7 citations

Ultracold Heteronuclear Fermi-Fermi Molecules

Kai Dieckmann

Department fu¨r Physik der Ludwig-Maximilians-Universit¨at, Schellingstrase4, 80799 Munich, GermanyMax-Planck-Institut fu¨r Quantenoptik, Hans-Kopfermann-Strase 1, 85748 Garching, Germany(Dated: October 7, 2008)We report on the first creation of ultracold bosonic heteronuclear molecules of two fermionicspecies,

Bulletin of the American Physical Society•Mar 18, 2009•0 citations
Institut fu¨r Quantenoptik, Leibniz Universita¨t Hannover, 30167 Hannover, Germany(Dated: September 15, 2010)We propose a cooling scheme for two-component fermions in optical lattices that employs theinternal structure of high-spin Fermi gases. Adiabatically changing the quadratic Zeeman couplingfrom a uniform distribution to a space dependent one allows for the creation of an inner spin-1/2 coresurrounded by spin-S wings. We show that, due to frustration, spin-S regions act via spin-changingcollisions as effective entropy absorbers for the spin-1/2 core with increasing efficiency at lowertemperatures and higher dimensions. We illustrate our scheme explicitly on 1D spin-3/2 fermions,showing that the entropy of the spin-1/2 Mott region can be significantly reduced. Our findingssuggest that the proposed method can be highly efficient, opening a feasible path for accessinganti-ferromagnetic order under current experimental conditions.
Spatial entropy redistribution plays a key role in adiabatic cooling of ultra-cold lattice gases. We show that high-spin fermions with a spatially variable quadratic Zeeman coupling may allow for the creation of an inner spin-1/2 core surrounded by high-spin wings. The latter are always more entropic than the core at high temperatures and, remarkably, at all temperatures in the presence of frustration. Combining thermodynamic Bethe Ansatz with local density approximation, we study the spatial entropy distribution for the particular case of one-dimensional spin-3/2 lattice fermions in the Mott phase. Interestingly, this spatially dependent entropy opens a possible path for an adiabatic cooling technique that, in contrast to previous proposals, would specifically target the spin degree of freedom. We discuss a possible realization of this adiabatic cooling, which may allow for a highly efficient entropy decrease in the spin-1/2 core and help access antiferromagnetic order in experiments on ultracold spinor fermions.
Recently, a cooling scheme for ultracold atoms in a bilayer optical lattice has been proposed (A. Kantian et al., arXiv:1609.03579). In their scheme, the energy offset between the two layers is increased dynamically such that the entropy of one layer is transferred to the other layer. Using the full-Hilbert-space approach, we compute cooling dynamics subjected to the scheme in order to show that their scheme fails to cool down two-component fermions. We develop an alternative cooling scheme for two-component fermions, in which the spin-exchange interaction of one layer is significantly reduced. Using both full-Hilbert-space and matrix-product-state approaches, we find that our scheme can decrease the temperature of the other layer by roughly half.
We propose an experimental procedure to cool fermionic atoms loaded into an optical lattice. The central idea is to spatially divide the system into entropy-rich and -poor regions by shaping the confining potential profile. Atoms in regions of high entropy per particle are subsequently isolated from the system. We discuss how to experimentally carry out this proposal, and perform a quantitative study of its efficiency. We find that the entropy per particle, sss, can typically be reduced by a factor of 10 such that entropies lower than s/kB∼0.2s/k_B \sim 0.2s/kB​∼0.2 can be reached. Cooling into highly sought-after quantum phases (such as an antiferromagnet) can thus be achieved. We show that this procedure is robust against variations of the experimental conditions.
We study the influence of the quadratic Zeeman effect on the Mott-insulator phases of hard-core 1D spin-3/2 fermions. We show that, contrary to spinor bosons, the quadratic Zeeman coupling preserves an SU(2)⊗SU(2) symmetry, leading for large-enough quadratic Zeeman coupling to an isotropic pseudo-spin-1/2 Heisenberg antiferromagnet. Decreasing the quadratic Zeeman coupling, this phase undergoes, depending on the scattering lengths, either a Kosterlitz-Thouless transition into a gapped dimerized phase or a commensurate-incommensurate transition into a gapless spin liquid. This rich phase diagram can be observed experimentally in four-component fermions in optical lattices under similar entropy constraints to those needed for Néel order in spin-1/2 gases.
We study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-metal-like atoms in optical lattices that can be effectively described by the two-band spin-1/21/21/2 Hubbard model including Hund's exchange coupling term. Our main goal is to investigate the effect of exchange interactions on finite-temperature magnetic phases for a wide range of lattice fillings. We use the dynamical mean-field theory approach and its real-space generalization to obtain finite-temperature phase diagrams including transitions to magnetically ordered phases. It allows to determine optimal experimental regimes for approaching long-range ferromagnetic ordering in ultracold gases. We also calculate the entropy in the vicinity of magnetically ordered phases, which provides quantitative predictions for ongoing and future experiments aiming at approaching and studying long-range ordered states in optical lattices.