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
Quantum complexity in condensed matter physics
S JulianUniversity of Toronto
•Emergent properties•Particle behaviour of fluctuating modes
•Broken symmetry and rigidity•Indirect interaction
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
Combinatorial chemistry vs. emergent properties
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
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
Dispersion relations for (quasi)particles
How to make a metal
Conventional phase transition: broken symmetry states
Conventional phase transition
Spontaneous symmetry breaking The susceptibility diverges
> rigidity
Mass enhancement
Magnetic pairing
Indirect interactions:
- One of the central principles of physics
Unusual “particle-like” excitations are possible in condensed matter systems
Propagating modes
Overdamped modes
The quantum critical point
At Tc, fluctuations diverge
Fe Cu
quantum critical superconductivity?
CePd2Si2 phase diagram
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
Anvil pressure cells
Phase diagram of Ca2RuO4
Antiferromagetic insulator
Ferromagnetic metal
Pressure / kbar
Tem
pera
ture
/ K
Structural transitions
Atomic orbitals in crystals
Orbital ordering
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.