A Mott insulator of fermionic atoms in an optical lattice

By R. Jördens, Niels Strohmaier, Kenneth Günter, H. Moritz, Tilman Esslinger. Nature, 2008

726 citations recorded by the source corpus.

Strong interactions between electrons in a solid material can lead to surprising properties. A prime example is the Mott insulator, in which suppression of conductivity occurs as a result of interactions rather than a filled Bloch band. Proximity to the Mott insulating phase in fermionic systems is the origin of many intriguing phenomena in condensed matter physics, most notably high-temperature superconductivity. The Hubbard model, which encompasses the essential physics of the Mott insulator, also applies to quantum gases trapped in an optical lattice. It is therefore now possible to access this regime with tools developed in atomic physics. However, an atomic Mott insulator has so far been realized only with a gas of bosons, which lack the rich and peculiar nature of fermions. Here we report the formation of a Mott insulator of a repulsively interacting two-component Fermi gas in an optical lattice. It is identified by three features: a drastic suppression of doubly occupied lattice sites, a strong reduction of the compressibility inferred from the response of double occupancy to an increase in atom number, and the appearance of a gapped mode in the excitation spectrum. Direct control of the interaction strength allows us to compare the Mott insulating regime and the non-interacting regime without changing tunnel-coupling or confinement. Our results pave the way for further studies of the Mott insulator, including spin-ordering and ultimately the question of d-wave superfluidity.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/236d4294738424b31def1ba482fd9a4254f1ed25

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Citations in the corpus

Engineered Open Systems and Quantum Simulations with Atoms and Ions (2012, background): “Despite impressive progress in this direction (Hofstetter et al., 2002; Köhl et al., 2005; Chin et al., 2006; Jördens et al., 2008; Schneider et al., 2008; Jördens et al., 2010; Esslinger, 2010), where quantum degeneracy is reached on the lattice, new cooling strategies are needed to achieve…”
Lattice gauge theory simulations in the quantum information era (2016, background): “[115], many paradigmatic system Hamiltonians have been realised in these systems, including SU(2) [116,117] and SU(N) fermionic Hubbardmodels [118–120], long-range interactions [121– 123], and static gauge fields [124–128], just to name a few.”
Quantum trajectories and open many-body quantum systems (2014, background): “A particularly important model that can also be realised in this way is the (fermionic) Hubbard model [77, 78],”
Cooling in strongly correlated optical lattices: prospects and challenges (2010, methodology): “For most experiments to date, the resulting fractional increase in entropy per particle is small, and S/N before the lattice turn-on is used to estimate the temperature in the lattice [74, 75, 116, 170].”
An SU(6) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling (2012, methodology): “If we set the system parameters so that the Mott insulator with n= 1 dominates in the ground state, excitations such as holes and double occupancies reduceWi(1) from unity, and thus the DPR decreases with the temperature, in contrast to the case of no lattice modulation where a higher amount of doub”
Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice (2011, background): “For example, the control of interactions in optical lattices has lead to the observation of Mott insulating phases [14, 15], providing new access to the physics of strongly correlated”
Disordered quantum gases under control (2009, result): “Landmark results have already been reported, including the observation of Mott insulator”
Quantum simulation of the Hubbard model with ultracold fermions in optical lattices (2018, neutral): “The first experiment to reveal the emergence of short-range spin correlations was performed in Zurich [140].”