quantum complexity in condensed matter physics
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Quantum complexity in condensed matter physics. S Julian University of Toronto. Emergent properties Particle behaviour of fluctuating modes Broken symmetry and rigidity Indirect interaction. Condensed Matter Physics. Fundamental Physics. Applied Physics. - PowerPoint PPT PresentationTRANSCRIPT
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Quantum complexity in condensed matter physics
S JulianUniversity of Toronto
•Emergent properties•Particle behaviour of fluctuating modes
•Broken symmetry and rigidity•Indirect interaction
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Condensed Matter Physics
Fundamental Physics Applied Physics-Quantum properties of many body systems-Noise (eg in electronic circuits)-Novel soft matter, elasticity and viscosity-Modeling the universe
-memory devices for computers-processors for computers-corrosion and catalysis-superconducting devices
energy
time
Elementary particle physics
biologyCondensed matter physics
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Combinatorial chemistry vs. emergent properties
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Empty boxes are more interesting than people think!
•At 0K: zero point motion
•At Low T: black-body radiation •At high T: electrons and positrons are created
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Analogy with quantum condensed matter physics:
•At 0K: zero point motion of phonon, electron-hole pairs, etc.
•At Low T: black-body radiation•Real phonons and electrons+holes
•At high T: electrons and positrons are created
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Dispersion relations for (quasi)particles
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How to make a metal
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Conventional phase transition: broken symmetry states
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Conventional phase transition
Spontaneous symmetry breaking The susceptibility diverges
> rigidity
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Mass enhancement
Magnetic pairing
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Indirect interactions:
- One of the central principles of physics
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Unusual “particle-like” excitations are possible in condensed matter systems
Propagating modes
Overdamped modes
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The quantum critical point
At Tc, fluctuations diverge
Fe Cu
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quantum critical superconductivity?
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CePd2Si2 phase diagram
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Methodology of condensed matter physics:
• Crystal growth:– Crystals are to us what stars are to astronomers
• Scattering:– A good way to find out what is inside something is to
throw something at it and see how it bounces off• Nano-physics:
– Scanning tunneling microscopy, point contact spectroscopy, etc.
• Low temperatures and high magnetic fields:– Dilution refrigeration
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Anvil pressure cells
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Phase diagram of Ca2RuO4
Antiferromagetic insulator
Ferromagnetic metal
Pressure / kbar
Tem
pera
ture
/ K
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Structural transitions
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Atomic orbitals in crystals
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Orbital ordering
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Summary
• The fundamental principles of quantum condensed matter physics are:– Emergent properties: new kinds of ‘particles’
emerge as complexity increases– Broken symmetry and rigidity– Indirect interactionsThe methodology focuses on crystal growth,
scattering and low temperatures.