Revolution in Physics PHYS 342 Modern Physics Revolution in Physics must unifies seemingly unrelated phenomena. Ultracold Atoms and Trappe Ions Mechanical Revolution: EM Revolution: Relativity Revolution: Unified falling apples on Unified electricity, Unified space, time and earth and the planets magnetism, and light gravity Today and Mar.23 Contents: motions in sky a) Revolution in physics –2nd Quantum revolution b) Quantum simulation, measurement, and information c) Atomic ensemble and quantum statistical (refer to Charpter10) d) Cooling and trapping of 6Li fermions e) Quantum simulation with ultracold atoms f) Quantum measurement with ultracold atoms Quantum Revolution: Unified particle and wave g) Quantum Information Basis h) Cooling and Trapping Charged Particles i) Preparation, Manipulation and Detection of 171Yb+ What is the second j) Trapped Ion Quantum Computers quantum revolution? k) Quantum Network Think different from Particle-Wave Duality Simulation of Nature using Quantum Software and Hardware (original ideas from Richard Feynman) “wave-like” : flying in the ” Nature isn’t classical, if you want to make a simulation of nature, space, messenger of the you’d better make it quantum mechanical.” world------ Information Software from quantum principles (quantum information) “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) “particle-like” : localized in the space, elements for Second Quantum Revolution the world------ Matter unifies Matter and Information at Quantum Level ! Particle-Wave duality Matter – Information duality Need Quantum Computer! Toys for Second Quantum Revolution My Favorite Toys : Trapped Atoms and Ions “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 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) Trapped Atoms and Ions 1989 Nobel Prize: 1997 Nobel Prize: Ion trap isolating Laser cooling and single quantum trapping atoms. particle. Steven Chu Hans Dehmelt Claude Cohen-Tannoudji Wolfgang Paul William Daniel Phillips 2001 Nobel Prize: 2012 Nobel Prize: Bose-Einstein condensation in dilute gases Manipulation of individual quantum systems Degenerate Fermi Gas Hybrid Atom-photon Ion Trap Quantum Computer Eric Cornell, Carl Wieman, Wolfgang Ketterle Serge Haroche and David J. Wineland and Condensation Interferometer And Network 7 US Physicists (4 from NIST/JILA), 2 France, 1 Germany Pauli Exclusion Principle Today and Mar.23 Contents: Fundamental principle -- Pauli Exclusion Principle a) Revolution in physics –2nd Quantum revolution Any fundamental particles with Odd/2 spin can not have the b) Quantum simulation, measurement, and information same set of quantum numbers in a quantum system. c) Atomic ensemble and quantum statistical (refer to Charpter10) d) Cooling and trapping of 6Li fermions e) Quantum simulation with ultracold atoms f) Quantum measurement with ultracold atoms g) Quantum Information Basis h) Cooling and Trapping Charged Particles spin=0,1,2,3,4.. i) Preparation, Manipulation and Detection of 171Yb+ j) Trapped Ion Quantum Computers k) Quantum Network spin=1/2,3/2,5/2... How to Label an Atomic State Mixture of Spin Up/Down 6Li Atoms Now we have seven quantum numbers for a certain atomic state. ( n, l , ml, s , ms, j, mj,I , mI, F, m F) Hyperfine Structure in a Magnetic Field e‐orbital e‐spin e‐total nuclei‐spin total 2p B 0 6 # 5 (for all electrons):1 2 670 nm 4 E 3 2 (for the outer electrons): 2 / 2s 1 2 1 1 Ground State(1s 2s ):J=1/2 Level 1 Spin ½ Up 1 = ,1 Now I =1, what is F, m ? 2 F Nuclear Spin: I=1 1 Level 2 Spin ½ Down 2 = ,0 2 1,2 States High B-Field Seeking----Requires Optical Trap 6Li Atoms for Fermionic Condensation Strong Interacting Systems in Nature Black Holes in String Theory High-Tc Neutron Supercond uctor Stars Universal Properties Ultracold Quark- Fermi Gas Gluon Plasma No Interaction (idea gas) Strong Interaction Scaling Invariance All fundamental material particles are fermions: Universal Properties ?? Fermionic condensation plays more significant roles in many-body physics Trivial Universality (PV=nRT) Many-body Strong Interaction From103 K to 10-7 K George Bertsch’s Problem L MOT Beam ( a problem for neutron star) T=700 K R -V 0 T=150 μK Slowing Zeeman Slower N=500 Million | a | L R 0 MOT Beam R -V0 The only length scale is the interparticle spacing L (n,T). Free and Forced Optical Trap Evaporative U = 0.7mK Cooling I =2MW/cm2 All thermodynamic and L T < 1 μK Size ~ 50 μm dynamic properties are N=200,000 Two spin component interacting only determined by density via s-wave quantum collisions. and temperature Optical Dipole Trapped Fermi Gas S-wave scattering Feshbach Resonance 1 g 3 3 3 u u agnet coils u B B B 1 1 = ,1 = ,0 2 2 electron spin, nuclear spin Optical Trap Loading Forced Evaporation Force Evaporative Cooling Weakly Interacting Regime cooling@ 330 G for weakly interacting Fermi Gas Strongly Interacting Regime cooling@ 834 G for strongly interacting Fermi Gas High-Field Imaging Phase Diagram for 6Li Ultracold Fermi Gas BEC Unitary BCS Strongly Interacting Degenerate Fermi Gases 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 Ballistic Expansion – Gas dynamics Hydrodynamic Expansion- Fluid Dynamics Noninteracting Fermi Gas Fermi Condensation or Strongly interacting Fermi gas.