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, spin-polarized 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

Be-Cu Torsion Rod

Torsion Bobcontaining helium

Drive

Detection

K

Io πτ 2=

High Q torsional oscillator for detecting non classical moment of inertia, or superfluidity, I.

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 aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

A carbon nanotube suspended between two conductors.

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

Pressure

Molecular solidinsulator

molecularmetal

Pressure

atomicmetal

The Wigner-Huntington Transition to Atomic Metallic Hydrogen (1935)

Predicted transition pressure:250 Kbar (0.25 megabar or 25 Gigapascal (GPa)

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 1990A-Phase (III) Geophys. Lab, Harvard, 1989-1990, 2005

Known High Pressure Phases of Solid Deuterium

1 megabar

E. Babaev, A. Sudbe, and N. W. Ashcroft, Nature, 431, 666, 2004.

"A superconductor to superfluid transition in liquid metallic hydrogen,"

Metallic superfluid

superconducting superfluid

Normal fluid

Electronic superconductor

Superconducting electronsSuperconducting protonsSuperfluidity of both together

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 forEach 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