Download ppt - Harvard Condensed Matter Theory group

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
• Feshbach resonances
• Optical lattices
• 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 with
strong electron correlations
High temperature superconductivity
Quantum magnetism
?
=
Electron fractionalization
electron
+
charge
spin
Applications of quantum materials:
High Tc superconductors
Applications of quantum materials:
Ferroelectric RAM
+ + + + + + + +
V
_ _ _ _ _ _ _ _
FeRAM in Smart Cards
Non-Volatile Memory
High Speed Processing
Modeling in physics
Modeling quantum systems
Analogue quantum computer. Simulation of
R. Feynman (1982)
one quantum system by another.
Fermionic atoms in optical lattices
Tc 93 K
U
t
t
Strongly correlated systems
Electrons in Solids
Atoms in optical lattices
Simple metals
Perturbation theory in Coulomb interaction applies.
Band structure methods wotk
Strongly Correlated Electron Systems
Band 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?
Antiferomagnetic order
Do we have d-wave pairing?
U
t
t
Vortices in fermionic superfluids
Vortices in high-Tc cuprates
Vortices in ultracold fermionic atoms
Experiments with fermionic superfluids
of cold atoms will help us understand
important basic properties of vortices
Pairing in systems with imbalanced
spin population
Pairing in polarized Fermi gas
Possible FFLO phase in CeCoIn5
New Era in Cold Atoms Research
Focus 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)