New State of Matter Revealed: Bose-Einstein Condensation

The Noble Prize in Physics 2001

by Zheng Zhao

Suranaree University of TechnologyM5810024

The Nobel Prize in Physics for 2001 was awarded jointly to:

—-“for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates.”

Eric CornellPrize share 1/3

Wolfgang KetterlePrize share 1/3

Carl WiemanPrize share 1/3

Source: https://www.nobelprize.org/nobel_prizes/physics/laureates/2001/

Biography [Wolfgang Ketterle]

Outline

Introduction of Bose-Einstein Condensation

BEC achieving in MIT

Summary

In 1957, born in Heidelberg, Germany. In 1976, University of Heidelberg In 1982, M.S Technical University in Munich In 1986, Ph.D Max Planck Institute

Wolfgang KetterlePrize share 1/3

In 1990, joined the group of David E. Pritchard in the Research Laboratory of Electronics at MIT (RLE)

In 1995, achieving BEC in sodium

Biography [Wolfgang Ketterle]

Introduction of Bose-Einstein Condensation

Biography [Wolfgang Ketterle]

Outline

BEC achieving in MIT

Summary

Introduction of Bose-Einstein Condensation

De Broglie (1929 Nobel Prize winner) proposed that all matter is composed of waves. Their wavelength are given by,

Q1: What is the Bose-Einstein Condensation

λ = hmv

= de Broglie wavelength h = Planck’s constant m = mass v = velocity

λ

Thermal De Broglie wavelength was given by,

λ = h2πmkBT

Introduction of Bose-Einstein CondensationQ1: What is the Bose-Einstein Condensation

= de Broglie wavelength h = Planck’s constant m = mass = Boltzmann constant T = temperaturekB

λ

Introduction of Bose-Einstein CondensationQ1: What is the Bose-Einstein Condensation

classical gas: T>>Tc “billiard balls”

T>Tc, λdB = h/mv ∝T1/2

“wave packets”T=Tcrit, λdB = d“Mater wave overlap”

, BECT=0, Pure Bose condensate “Giant matter wave”

Source: https://www.youtube.com/watch?v=shdLjIkRaS8

Introduction of Bose-Einstein CondensationQ1:What is Bose-Einstein Condensation (BEC)?

In brief, creating a BEC is thus simple in principle:

“make a gas extremely cold until the atomic wave packets start to overlap.”

But, It takes 70 years to accomplish =

BEC achieving in MIT

Biography [Wolfgang Ketterle]

Outline

Introduction of Bose-Einstein Condensation

Summary

BEC achieving in MIT

Q2: How is BEC made?

• Laser Cooling — precool the gas atoms

• Magneto-optical Trap (MOT) — trap gas atoms

• Evaporative Cooling — second cooling stage

The Nobel Prize in Physics for 1997 was awarded jointly to:

—-“for development of method to cool and trap atoms with laser light.”

Steven Chu Claude Cohen-Tannoudji William D.PhillipsPrize share 1/3 Prize share 1/3 Prize share 1/3

• Laser Cooling — precool the gas atoms

BEC achieving in MIT Q2: How is BEC made?

Source: https://www.nobelprize.org/nobel_prizes/physics/laureates/1997/

BEC achieving in MIT

• Photons — particles carrying momenta like Ping-Pong Balls

• Slowing the motion of an atom —- bouncing laser light off the atomsPhotons

“ping-pong Balls”an atom

“bowling ball”

1. “Bowling ball” and “Ping-Pong balls”

• Laser Cooling — precool the gas atomsQ2: How is BEC made?

BEC achieving in MIT

2. Tuning the laser

• Only laser light with the correct color (frequency) can be absorbed by the atoms

• If the color is wrong, the atoms cannot absorb the photons

• Doppler Effect — avoid accelerating the atoms (blast off atoms)

• Laser Cooling — precool the gas atomsQ2: How is BEC made?

BEC achieving in MIT

• right color laser — photons to be absorbed by an approaching atom — the atom will be slowed down.

• wrong color laser — photons can not be be absorbed by the receding atom — Doppler effect.

1. laser trapping

approaching atom slow down

receding atom do not change

Q2: How is BEC made?

• Magneto-optical Trap (MOT) — trap gas atoms

• lasers are sent in from all the different directions, the atoms can get cold very quickly.

1. laser trapping

BEC achieving in MIT Q2: How is BEC made?

• Magneto-optical Trap (MOT) — trap gas atoms

• Problem: 1. Laser cooling — atoms — 1/10000K— This is still too hot for BEC.

• Solution: Evaporative cooling

BEC achieving in MIT

thermos bottle

2. Magnetic trapping

Q2: How is BEC made?

• Magneto-optical Trap (MOT) — trap gas atoms

=

• The atoms — tiny compasses (or magnet) — can be pulled by magnetic fields.

• A magnetic field — push the atoms inwards — magnetic trap.

• http://www.colorado.edu/physics/2000/bec/mag_trap.html

BEC achieving in MIT

2. Magnetic trapping

Q2: How is BEC made?

• Magneto-optical Trap (MOT) — trap gas atoms

BEC achieving in MIT

thermos bottle

2. Magnetic trapping

Magneto-optical Trap (MOT)

=

Q2: How is BEC made?

• Magneto-optical Trap (MOT) — trap gas atoms

BEC achieving in MIT

• Evaporation takes heat.

• eg. A cup of coffee — steam escapes — faster atoms escape — leaving slower ones

• http://www.colorado.edu/physics/2000/bec/evap_cool.html

• Evaporative Cooling — second cooling stageQ2: How is BEC made?

BEC achieving in MIT

Biography [Wolfgang Ketterle]

Outline

Introduction of Bose-Einstein Condensation

Summary

Time-of-flight absorption images of BEC with sodium in MIT

BEC achieving in MIT

Source: (http://cua.mit.edu/ketterle_group/animations.htm)

Observation of BEC with sodium by Time of flight absorption images (MIT)

BEC achieving in MIT

Source: (http://cua.mit.edu/ketterle_group/animations.htm)

BEC achieving in MIT

Observation of Bose-Einstein condensation by absorption images. Shown — absorption vs. two spatial dimensions. left: above the transition point; middle: just after the condensate appeared; right: after further evaporative cooling — left an almost pure condensate.

Source: (http://cua.mit.edu/ketterle_group/animations.htm)

Biography [Wolfgang Ketterle]

Outline

Introduction of Bose-Einstein Condensation

BEC achieving in MIT

Summary

Summary

• BEC shares the same "specialness" with laser light.

• Outlook: When atoms behave as wave

• The fifth state of matter — BEC.

Summary

(http://cua.mit.edu/ketterle_group/animations.htm)

• atom optics (studying the optical properties of atoms)

• precision atomic clocks

• other measurements of fundamental standards

• communications and computation.

• Fundamental understanding of quantum mechanics.

• This is a completely new area. Applications are too early to predict. The atom laser can be used in:

• Outlook: When atoms behave as wave

• W. Ketterle, When Atoms Behave as Wave: Bose-Einstein Condensation and The Atom Laser, Nobel lecture, Dec 2001

• D. E. Pritchard, Bose-Einstein Condensation: A Double Pot of Gold. (http://web.mit.edu/physics/news/physicsatmit/physicsatmit_02_bec.pdf)

• Homepage of the Nobel e-Museum. (https://www.nobelprize.org/nobel_prizes/physics/laureates/2001/)

• BEC Homepage at the University of Colorado. (http://www.colorado.edu/physics/2000/bec/index.html)

• Ketterle Group Homepage. (http://www.cua.mit/ketterle_group/).

Reference

Thank you for your attention

Welcome questions

BEC achieving in MIT

• Using the Doppler Effect to avoid accelerating the atoms (blast off atoms)

• Laser Cooling — precool the gas atomsQ2: How is BEC made?

3. Using the Doppler Effect

approaching

chasing

BEC achieving in MIT

3. Using the Doppler Effect

• The atom — receding from the laser source — the wavelength — longer — redshift

• The atom — approaching the laser source — the wavelength — shorter — blueshift

• The electron — do not absorb redshift photon — the photon will go through the atom

• Laser Cooling — precool the gas atomsQ2: How is BEC made?