PHYS 342 Modern Physics Ultracold Atoms and Trappe Ions

Today and Mar.23 Contents:a) Revolution in physics – 2nd Quantum revolutionb) Quantum simulation, measurement,  and informationc)  Atomic ensemble and quantum statistical (refer to Charpter10)d) Cooling and trapping of 6Li fermionse) Quantum simulation with ultracold atomsf)  Quantum measurement with ultracold atomsg) Quantum Information Basish) Cooling and Trapping Charged Particlesi) Preparation, Manipulation and Detection of 171Yb+ j) Trapped Ion Quantum Computers k) Quantum Network

Revolution in Physics must unifies seemingly unrelated phenomena.

Revolution in Physics

Mechanical Revolution:Unified falling apples on earth and the planets motions in sky

EM Revolution: Unified electricity, magnetism, and light

Relativity Revolution: Unified space, time and gravity

Quantum Revolution: Unified particle and wave

What is the second quantum revolution?

Think different from Particle-Wave Duality

“wave-like” : flying in the space, messenger of the world------ Information

“particle-like” : localized in the space, elements for the world------ Matter

Particle-Wave duality Matter – Information duality

Simulation of Nature using Quantum Software and Hardware

Second Quantum Revolution unifies Matter and Informationat Quantum Level !

” Nature isn’t classical, if you want to make a simulation of nature,you’d better make it quantum mechanical.”

Software from quantum principles (quantum information)

(original ideas from Richard Feynman)

“How can we simulate the quantum mechanics?….Can you do it with a new kind of computer - a quantum computer? “

Hardware from quantum devices (quantum matter)

Need Quantum Computer!

Toys for Second Quantum Revolution

“We can create states of quantum coherent or entangled matter and energy that likely existed nowhere else in the Universe. These new man-made quantum states have wide application to the development of computers, communications systems, sensors and compact metrological devices.“

---- by J.P.Dowling and G.J.Milburn

My Favorite Toys : Trapped Atoms and Ions

6Li Atom: Fermi Condensation 40Ca+ Ion: Ground State

Interaction, Spin, Dimensionality, Filling, Impurity, Coherence …All Tunable !

Developed to: Atomic Matter Physics, Quantum Simulator,Quantum Sensors, Atomtronics …

Trapped Quantum Particles (Historical) 1989 Nobel Prize: Ion trap isolating single quantum particle.Hans DehmeltWolfgang Paul

1997 Nobel Prize: Laser cooling and trapping atoms.Steven ChuClaude Cohen-TannoudjiWilliam Daniel Phillips

2001 Nobel Prize: Bose-Einstein condensation in dilute gasesEric Cornell, Carl Wieman, Wolfgang Ketterle

7 US Physicists (4 from NIST/JILA), 2 France, 1 Germany

2012 Nobel Prize: Manipulation of individual quantum systems Serge Haroche and David J. Wineland

Trapped Atoms and Ions

Degenerate Fermi Gasand Condensation Ion Trap Quantum Computer

And NetworkHybrid Atom-photonInterferometer

Today and Mar.23 Contents:a) Revolution in physics – 2nd Quantum revolutionb) Quantum simulation, measurement,  and informationc)  Atomic ensemble and quantum statistical (refer to Charpter10)d) Cooling and trapping of 6Li fermionse) Quantum simulation with ultracold atomsf)  Quantum measurement with ultracold atomsg) Quantum Information Basish) Cooling and Trapping Charged Particlesi) Preparation, Manipulation and Detection of 171Yb+ j) Trapped Ion Quantum Computers k) Quantum Network

Pauli Exclusion Principle

Fundamental principle -- Pauli Exclusion PrincipleAny fundamental particles with Odd/2 spin can not have the same set of quantum numbers in a quantum system.

spin=0,1,2,3,4..

spin=1/2,3/2,5/2...

How to Label an Atomic StateNow we have seven quantum numbers for a certain atomic state.

( n, l , ml, s , ms, j, mj , I , mI, F, mF)e‐orbital e‐spin nuclei‐spine‐total total

(for the outer electrons): 2 /

Now I =1, what is F, mF ?

#(for all electrons):1 2

Mixture of Spin Up/Down 6Li Atoms

Hyperfine Structure in a Magnetic Field

Level 1 Spin ½ Up 1 1,21

=

Level 2 Spin ½ Down 0,21

2 =

670 nm

2s

2p

Ground State(1s22s1):J=1/2

Nuclear Spin: I=1

1,2 States High B-Field Seeking----Requires Optical Trap

12

34

56

E

B 0

All fundamental material particles are fermions:Fermionic condensation plays more significant roles in many-body physics

6Li Atoms for Fermionic Condensation

UniversalProperties

Black Holes in String Theory Neutron

Stars

Quark-Gluon Plasma

UltracoldFermi Gas

High-TcSupercond

uctor

Strong Interacting Systems in Nature

Strong Interaction Universal Properties ??

No Interaction (idea gas) Scaling InvarianceTrivial Universality (PV=nRT)

Many-body Strong Interaction

L

-V0

R

George Bertsch’s Problem ( a problem for neutron star)

0|| RLa

-V0

R

L

Two spin component interacting via s-wave quantum collisions.

The only length scale is the interparticle spacing L (n,T).

All thermodynamic and dynamic properties are only determined by density and temperature

T=700 K

Slowing BeamMOT

Zeeman Slower

MOT Beam

Free and ForcedEvaporative

CoolingT < 1 μK

N=200,000

Optical TrapU = 0.7mKI =2MW/cm2

Size ~ 50 μm

T=150 μKN=500 Million

From103 K to 10-7 K

Optical Dipole Trapped Fermi Gas

agnet coils

1,21

= 0,21

=

spinnuclear spin,electron

S-wave scattering Feshbach Resonance

g1

B

u3

B

u3

B

u3

Optical Trap Loading

Forced Evaporation

Weakly Interacting Regime cooling@ 330 G for weakly interacting Fermi Gas

Strongly Interacting Regime cooling@ 834 G for strongly interacting Fermi Gas

Force Evaporative Cooling

High-Field Imaging Phase Diagram for 6Li Ultracold Fermi Gas

UnitaryBEC BCS

BEC-BCS crossover: A pure theoretical problem in condensed matter physics before 2002.Become real experiments in atomic physic after 2002 0.01 U0， T/TF = 0.45 0.001 U0， T/TF = 0.18

Strongly Interacting Degenerate Fermi Gases

Ballistic Expansion – Gas dynamics

Noninteracting Fermi Gas

Hydrodynamic Expansion- Fluid Dynamics

Fermi Condensation or Strongly interacting Fermi gas