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Transcript
Current “Hot” Areas of Research
in Physics
Mature Physics
and
Hot Physics
•
•
•
•
•
•
•
•
•
•
Cold atom physics (Bose-Einstein condensation
and degenerate Fermi gases),
Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
Biophysics
Soft condensed matter,
Hydrogen storage—the energy problem
Astrophysics: dark matter and dark energy
Quantum computing,
Neutrino physics,
String theory
Particle physics, the Large Hadron Collider, the
Higgs particle, Supersymmetric particles
•
•
•
•
•
•
•
•
•
•
Cold atom physics (Bose-Einstein condensation
and degenerate Fermi gases),
Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
Biophysics
Soft condensed matter,
Hydrogen storage—the energy problem
Astrophysics: dark matter and dark energy
Quantum computing,
Neutrino physics,
String theory
Particle physics, the Large Hadron Collider, the
Higgs particle, Supersymmetric particles
Bose-Einstein Condensation (BEC)
In 1924 Einstein predicted that a gas of bosons
(identical integral spin particles) would have a
phase transition: below a finite critical
temperature the ground energy state or zero
momentum state would be macroscopically
occupied by particles.
It was believed that superfluid helium was a
demonstration of BEC but this was
controversial and difficult to demonstrate
experimentally.
In 1979 the first confined gas of bosons, spinpolarized atomic hydrogen was stabilized, but
the conditions for BEC were difficult to achieve.
In the 1980s atomic physicists learned how to
cool alkali atoms (sodium, rubidium,etc.) to
microkelvin temperatures
Alkali gases (metastable) were confined in
magnetic traps that isolated them from walls and
prevented condensation. They were cooled by
evaporative cooling--removal of hot atoms,
allowing the remaining atoms to thermalize to a
lower temperature-- and finally BEC at
nanokelvin Temperature!
Vertical: the probability the an energy state is
occupied
Horizontal: energy increasing radially.
Cornell and Weiman (U. of Colorado) and
Ketterle (MIT) received Nobel Prize
Almost every Physics department has a cold
atom group.
Atomic physicists have become condensed
matter physicists.
5-10 new publications/week: BEC atoms are
superfluids; superfluid vortices, atom laser, cold
fermions; superfluid fermions, etc.
•
•
•
•
•
•
•
•
•
•
Cold atom physics (Bose-Einstein condensation
and degenerate Fermi gases),
Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
Biophysics
Soft condensed matter,
Hydrogen storage—the energy problem
Astrophysics: dark matter and dark energy
Quantum computing,
Neutrino physics,
String theory
Particle physics, the Large Hadron Collider, the
Higgs particle, Supersymmetric particles
High Q torsional
oscillator for
detecting non
classical moment
of inertia, or
superfluidity, I.
Be-Cu
Torsion Rod
Torsion Bob
containing
helium
Drive
Detection
I
 o  2
K
Supersolid
Response.
Solid helium
exhibits
superflow.
Nanophysics and Lower dimensional physics.
In the late 1980s physicists at IBM Watson
Research laboratories found that small high
purity samples did not obey Ohm’s Law: V=iR
i
Electron quantum
mechanical amplitude could
move on the upper or lower
path and get quantum
interference.--if there was no
inelastic scattering and the
electrons maintained there
phase over the path length.
This led to rapid development of the study of
materials on a microscopic-nanoscopic-scale and
the study of materials in lower dimensions. What
developed:
•Integral and fractional quantum Hall effect-2-dimensional electron
gases.
•Single electron transistor
•Quantum dots; Coulomb blockade; artificial atoms
•Bucky balls
•Carbon nanotubes
•Etc.
Quantum dot and circuit
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
A carbon nanotube suspended between two conductors.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Raman scattering
spectrum
Of vibrational
modes in the
Single walled
carbon NT
Fracture of nanoscopic 2d organosilicate glass
•
•
•
•
•
•
•
•
•
•
Cold atom physics (Bose-Einstein condensation
and degenerate Fermi gases),
Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
Biophysics
Soft condensed matter,
Hydrogen storage—the energy problem
Astrophysics: dark matter and dark energy
Quantum computing,
Neutrino physics,
String theory
Particle physics, the Large Hadron Collider, the
Higgs particle, Supersymmetric particles
The Wigner-Huntington Transition
to Atomic Metallic Hydrogen
(1935)
Predicted transition pressure:
250 Kbar (0.25 megabar or 25 Gigapascal (GPa)
Pressure
Pressure
Molecular solid
insulat or
molecular
met al
at omic
met al
IMPORTANT DEVELOPMENTS
 Predicted Metal Insulator Transition in Solid Hydrogen
Wigner-Huntington, 1935
 Predicted High Temperature Superconductivity in Metallic
Hydrogen Ashcroft, 1968
 Metastability of metallic hydrogen, liquid at T=0 K
Russia (Kolos, Kagan), 1972
 New Megabar Phases in the High Pressure Solid Hydrogens
~1980-2005
BSP Amsterdam 1981, Harvard 1990
A-Phase (III) Geophys. Lab, Harvard, 1989-1990, 2005
Known High Pressure Phases of Solid Deuterium
1 megabar
Superconducting electrons
Superconducting protons
Superfluidity of both together
Metallic
superfluid
Normal fluid
superconducting
superfluid
Electronic superconductor
E. Babaev, A. Sudbe, and N. W. Ashcroft,
Nature, 431, 666, 2004.
"A superconductor to superfluid transition in
liquid metallic hydrogen,"
Diamonds and Gasket
The heart of a
diamond anvil cell
(DAC). Pressures
higher than 3 million
bars can be achieved
on samples inside the
gasket hole.
• Cold atom physics (Bose-Einstein condensation and
degenerate Fermi gases),
• Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
• Biophysics
• Soft condensed matter,
• Hydrogen storage—the energy problem
• Astrophysics: dark matter and dark energy
• Quantum computing,
• Neutrino physics,
• String theory
• Particle physics, the Large Hadron Collider, the Higgs
particle, Supersymmetric particles
A method for rapid sequencing of DNA
Sequencing of DNA: a different conductance for
Each base (C,G, A, T). In principle the DNA code
Could be read in one millisecond.
• Cold atom physics (Bose-Einstein condensation
and degenerate Fermi gases),
• Condensed matter:
supersolids, correlated electrons, nanophysics
metallic hydrogen, etc,
• Biophysics
• Soft condensed matter,
• Hydrogen storage—the energy problem
• Astrophysics: dark matter and dark energy
• Quantum computing,
• Neutrino physics,
• String theory
• Particle physics, the Large Hadron Collider, the
Higgs particle, Supersymmetric particles