Mecánica Estadística Avanzada: introduction to superconductivity & superfluidity

Francesca Maria Marchetti


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Profesora


Francesca Maria Marchetti
Tel. 91 497 5590
e-mail: francesca.marchetti (at) uam.es

Departamento de Fisica Teorica de la Materia Condensada
6a planta
despacho 606

SC levitation
vortices BEC


[from Wikimedia Commons]
[from Alkali&Quantum Gases MIT]

Calendario y aula


Material complemen.


Bibliography





Calendario y aula

VOLVER ARRIBA

Classes are on
Monday    at  11.30
Tuesday   at  9.30
Thursday at  11.30


JANUARY



Mon 21
Tue 22
Thu 24
Part I
Mon 28
Tue 29
Thu 31

FEBRUARY



Mon 4
Tue 5
Thu 7

Mon 11
Tue 12
Thu 14

Mon 18
Tue 19
Thu 21

Mon 25
Tue 26
Thu 28

MARCH


Mon 4
Tue 5
Thu 7

Mon 11
Tue 12
Thu 14

Mon 18
Tue 19 N.B. at 11.30!!
Thu 21
Part II
Mon 25
Tue 26
Thu 28
Semana santa
APRIL



Mon 1
Tue 2
Thu 4

Mon 8
Tue 9
Thu 11

Mon 15
Tue 16
Thu 18 2 hours
Mon 22
Tue 25
Thu 25 2 hours
Mon 29
Tue 30


MAY





Thu 2
last week
Mon 6
Tue 7






Mon 20
Tue 21

exams






Aula: 402 del modulo 03 (Ciencias)


Material complem.


Part I: superfluidity (bosons)
Part II: superconductivity (fermions)




VOLVER ARRIBA


Lecture 1
Lecture 2&3&4
Lecture 5

Lecture 6&7
Lecture 8&9
&10
Lecture 11&
12&13
Lecture 14&15&16
Lecture 17&18

Lecture 19
Lecture 20

Lecture 21&22
Lecture 23&24
Lecture 25&26
Lecture 27&28&29
Lecture 30&31
Lecture 32&33
Lecture 34&35
Lecture 36&37
Lecture 38
Lecture 39&40

Problem set 1
Solutions
Problem set 2
Problem set 3
Problem set 4
Problem set 5
Problem set 6
Problem set 7
Problem set 8
Problem set 9



































































VOLVER ARRIBA


























N.B. The supplementary materials underlined in yellow are (advanced) research articles among which you can choose one or two articles for the presentation (20 minutes) at the end of the course. **Presentations are an essential part of the evaluation together with the Problem  sets**

Lecture 0
Presentation of the course

Part I: superfluidity (bosons)


Lecture 1
Historical introduction to Bose-Einstein condensation (BEC) and sperfluidity

Lecture 2&3&4
The ideal Bose gas
Gas in a 3D box
Thermodynamic limit
Problem set 1
Solutions: Mathematica scritpt
Solutions: Matlab script: numerics_example.m, int_num.m, fun_zero.m
Plots
Lecture 5
Trapped ideal gases (Tc for BEC, condensate fraction)
BEC in ideal Bose gases: statistical saturation of the excited states

Lecture 6&7
One-body density matrix & off-diagonal long range order
Formalism of second quantisation
Order parameter
Problem set 2
Lecture 8&9&10
The weakly-interacting Bose gas
Excitation spectrum
The Bogoliubov transformation
Sound velocity
Healing length








Lecture 11&12&13
BEC and superfluidity:
Landau criterion
Defect moving through a superfluid
Condensate depletion due to interactions
One-body density matrix in weakly interacting Bose  gases
Problem set 3
Lecture 14&15&16
Zero temperature: The time dependent Gross-Pitaevskii equation
Conservation laws: continuity equation
Stationary solutions
Landau free energy, order parameter, 2nd order phase transition
Small amplitude oscillations: Bogoliubov-de Gennes equations

Bogoliubov spectrum of excitations



Lecture 17&18 --- Application
Superfluid velocity & quantisation of circulation

Vortex line solutions
Healing length
Rotation of superfluids
Energy of a vortex solution
Problem set 4
Lecture 19
Trapped condensates
Thomas-Fermi limit
Problem set 5
Lecture 20 --- Applications
Time of flights measurements: expansion of a BEC
Interference between two condensates
Problem set 6
Lecture 21&22
Towards understanding the experiments:
Alkali atoms
Density and momentum distributions

Short introduction to experiments in cold gases
Cooling, trapping & imaging techniques

Experiments on:
*expanding condensates
*interference between  two condensates
*determining the Bogoliubov spectrum
*rotating gases (vortices)
*...



Part II: superconductivity (fermions)


Lecture 23&24
Ideal Fermi gas (Sommerfeld theory of metals)
Fermi-Dirac distribution vs. Maxwell-Boltzmann
Zero temperature: Fermi energy, zero point pressure, compressibility
Thermal properties: Fermi temperature, heat capacity

Problem set 7
Lecture 25&26
Introduction to superconductivity:
Phenomenology
Experimental evidences

Lecture 27&28&29
Microscopic mechanisms behind superconductivity
The one-pair Cooper problem
Cooper pairs
The electron-phonon interaction
Problem set 8
Lecture 30&31
BCS theory at zero temperature
Reduced Hamiltonian
BCS ground state: pair operators

Fock states versus coherent states
(number of particles and phase as conjugate variables)


Lecture 32&33
Variational calculation
Gap and number equations
Condensate energy and spectrum of excitations

Lecture 34&35
Mean-field approximation
Bogoliubov transformation: quasi-particles
BCS theory at finite temperature
Bogoliubov-de Gennes equations
Problem set 9


Lecture 36&37
Introduction to the BEC-BCS crossover
Basic scattering theory
Scattering length

T-matrix formalism
Born approximation



Lecture 38  --- Application
Relevance of the BEC-BCS crossover to cold atoms
Feshbach resonances

Changing the interaction strength

Lecture 39&40
BEC-BCS crossover at zero temperature
T=0 variational calculation
Contact interaction and analytical solutions

BEC-BCS crossover at finite temperature

Problem set 10


The final course presentations will be on Monday the 20th of May 2012 AND Tuesday the 21th of May 2012 (20 min. = 15 min. presentation, 5 min. discussion)
Let us discuss well in advance
(you can contact me at francesca.marchetti (at) uam.es) the choice of a topic

Student's name
date & time
Title
Angel Gabriel Rivas Fonfria
20/05/13 -- 10:00-10:30
Intereference between two condensates:Fock vs. coherent states
Alberto Martin Jimenez
20/05/13 -- 10:30-11:30
Josephson effect in superfluids and superconductors
Javier Galego Pascual 20/05/13 -- 11:30-12:00
Spontaneous symmetry breaking,
Phase transitions, spontaneous symmetry breaking and the Goldstone mode
Alvaro Esteban Prieto
20/05/13 -- 12:00-12:30
Measurements of coherence & ODLRO:  from quantum optics to ultracold gases
David Hernandez Merino 20/05/13 -- 12:30-13:00
Flux quantisation and vortices in superconductors and superfluids



Francisco Romero Ferrero &
Sara Jimenez Puertas
21/05/13 -- 10:00-11:00
Landau criterion, Cherenkov waves and drag force in weakly interacting Bose condensates
Andrea Santamaria Garcia &
Iñigo Alzueta Perez
21/05/13 -- 11:00-12:00 Feshbach resonances &
(Numerical solutions of the gap and number equations in) the BEC-BCS crossover
Manuel Lara Astiaso 21/05/13 -- 12:00-12:30 Polarised Fermi gases
Jose Benito Llorens
21/05/13 -- 12:30-13:00 Deviations from Einstein's picture of an ideal saturated Bose gas


Examples of other presentations from previous year courses
Josephson junctions,
The concept of phase in superfluids and superconductors: interference between two condensates and Josephson effect
From 1 to N Cooper pairs
Measurement of energy and ground-state occupation in ultracold atomic BECs
Fermi liquid description and its breakdown
Majorana fermions: concept and physical realisation


Bibliography


VOLVER ARRIBA

Part I
  1. L. Pitaevskii & S. Stringari, Bose-Einstein Condensation, Clarendon Press, Oxford (2003)
  2. A. J. Leggett, Quantum Liquids --- Bose Condensation and Cooper Pairing in Condensed-Matter Systems, Oxford Graduate Texts, Oxford (2006)
  3. C. J. Pethick & H. Smith, Bose-Einstein Condensation in Dilute Gases, Cambridge University Press, Cambridge (2002)
  4. Bose Einstein Condensation, ed. A. Griffin, D. W. Snoke & S. Stringari, Cambridge University Press, Cambridge (1995)
  5. My lecture course notes on superfluidity (to appear towards the end of the course)
Part II
  1. Ashcroft & Mermin, Solid State Physics
  2. C. Kittel, Introduction to Solid State Physics
  3. P. G. de Gennes, Superconductivity of Metals and Alloys, Westview Press, Oxford (1966)
  4. M. Tinkham, Introduction to Superconductivity, Dover Publications, New York (1996)
  5. P. Phillips, Advanced Solid State Physics, Westview Press, Oxford (2003)
  6. J. R. Schrieffer, Theory of Superconductivity, Westview Press, Oxford (1964)
  7. Lecture notes on Superconductivity from Alfredo Levy Yeyati




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