Modeling strongly correlated electron systems using cold atoms Eugene Demler Physics Department Harvard University.

Modeling strongly correlated electron systems using cold atoms

Eugene Demler

Physics Department

Harvard University

Bose-Einstein condensation

Scattering length is much smaller than characteristic interparticle distances. Interactions are weak

New Era in Cold Atoms Research

Focus on Systems with Strong Interactions

• Optical lattices

• Feshbach resonances

• Low dimensional systems

Why are we interested in quantum systems with strong interactions?

Strongly correlated electron systems in novel quantum materials

Transition metals and their oxides (including cuprates, manganites), actinides, lanthanides, heavy fermion compounds, organic materials, …

Unusual properties of materials withstrong electron correlations

High temperature superconductivity

Quantum magnetism

Electron fractionalization

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= +electron charge spin

Applications of quantum materials:High Tc superconductors

Applications of quantum materials: Ferroelectric RAM

Non-Volatile Memory

High Speed Processing

FeRAM in Smart Cards

V+ + + + + + + +

_ _ _ _ _ _ _ _

Modeling in physics

Modeling quantum systems

R. Feynman (1982)

Analogue quantum computer. Simulation of one quantum system by another.

Tc 93 K

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Fermionic atoms in optical lattices

Strongly correlated systemsAtoms in optical latticesElectrons in Solids

Simple metalsPerturbation theory in Coulomb interaction applies. Band structure methods wotk

Strongly Correlated Electron SystemsBand structure methods fail.

Novel phenomena in strongly correlated electron systems:

Quantum magnetism, phase separation, unconventional superconductivity,high temperature superconductivity, fractionalization of electrons …

Examples of questions that can be addressed in experiments with cold atoms

Can we understand high Tc cuprates using the fermionic Hubbard model?

t

U

t

Antiferomagnetic order

Do we have d-wave pairing?

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Vortices in fermionic superfluids

Experiments with fermionic superfluids of cold atoms will help us understand important basic properties of vortices

Vortices in ultracold fermionic atomsVortices in high-Tc cuprates

Pairing in systems with imbalanced spin population

Possible FFLO phase in CeCoIn5

Pairing in polarized Fermi gas

New Era in Cold Atoms ResearchFocus on Systems with Strong Interactions

Goals

• Resolve long standing questions in condensed matter physics (e.g. origin of high temperature superconductivity)

• Resolve matter of principle questions (e.g. existence of FFLO phase)

• Study new phenomena in strongly correlated systems (e.g. coherent far from equilibrium dynamics)