Superhot Among the Ultracool.

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Superhot Among the Ultracool.
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Deborah S. Jin

• Works at Joint Institute for Laboratory
  Astrophysics
• Collaborates with National Institute of Standards
  and Technology and University of Colorado in
  Boulder
• Work began in 1995, when two other JILA
  colleagues produced first Bose-Einstein
  condensate (Eric A. Cornell and Carl E. Wieman,
  who later won 2001 Nobel Prize along with
  Wolfgang Ketterle of MIT)
• Worked to discover the Fermionic condensate

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Two Types of Particles

• Bosons
• Have integer spins
• Bosons includes photons
• Also includes atoms with even number of protons,
  neutrons, and electrons
• Fermions
• Have half-integer spins
• Are the basic building blocks of ordinary matter
• Include electrons, protons, and neutrons
  individually
• Also includes atoms with odd number of those
  three constituents
• Hard to get them to act in single quantum state
  due to Pauli exclusion principle

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Difference between Bosons and Fermions
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Superfluids

• Type of matter that can flow endlessly without
  viscosity
• Occurs only at low temperatures in cold condensed
  atomic gases
• Needs certain quanta of energy to be rotated
• When rotated, circulates around quantized vortex
  lines (Thuneberg)

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Superconductors

• Have no resistance to electrical flow
• Occurs at extremely low temperatures
• Electrons with opposite spins form pairs
• Lack interior magnetic field, called Meissner
  effect
• Meissner effect looks like levitation

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Feshbach Resonance

• Found in systems with more than one degree of
  freedom (examples position and momentum)
• System could turn into bound state between
  certain degrees of freedom
• Scattering of particles away from each other is
  enhanced
• Particles have quantum coherence with each other
  though
• Means that they have fixed relationship with each
  other
• System has approximately energy needed to create
  bound state (Kleppner)

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Bose-Einstein Condensate

• Millions of boson atoms enter identical quantum
  state
• Also share same quantum wave therefore
• Happens near absolute zero
• Act like a single super-atom
• Proven by observing vortex structure (Cho)

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Making Condensates

• Jin was able to figure out how to consistently
  produce Bose-Einstein condensates
• Used systems of lasers and magnetic fields to
  trap atoms
• Hotter atoms expelled from trap, removing energy
• Cooling continues until condensate forms, near
  absolute zero
• Used fewer lasers and simpler setup than others

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Fermi Gas

• In 1999 made degenerate Fermi gas
• Persuaded fermions to stack up in the lowest
  quantum states, one per state
• Used one type of atom (potassium-40) and put it
  into two different spin states
• Spin state relates atoms behavior in magnetic
  fields
• Different spin states mean fermions could collide
  and exchange energy, and just have to get rid of
  high energy ones until only cool ones remained

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Fermionic Condensate

• Next goal was to get fermions strongly attracted
  to each other
• Fiddled with magnetic fields to induce Feshbach
  resonances
• Control interactions between potassium-40 atoms
• Make them attracted to each other
• In 2003 able to make molecules of fermions,
  creating Cooper pairs
• Two fermions together can form bosons
• Then formed their condensation (Seife)

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Velocity-Distribution Graph for BEC and FC
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Conclusions

• Proved the existence of the Fermionic condensate
• Her research showed that fermions didnt exist as
  molecules
• Not chemically bound together
• Instead existed as interacting pairs
• Still form a strong connection though
• Further research of Fermi condensate could be
  used to find room-temperature superconductors,
  since both have particles forming pairs

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The End