Cold atoms Lecture 1. 20. September 2006 Low temperature physics (borrowed from an undergraduate course) Existence absolutní nuly Teploty ve vesmíru Teploty ve vesmíru Nízké teploty v laboratoři (jen výběr !!) Naše hlavní téma Nízké teploty v laboratoři (jen výběr !!) Chlazení jadernou adiabatickou demagnetisací Kryostat, kde byla dosažena rekordní teplota 100 pK Spinová magnetická susceptibilita monokrystalu rhodia Introductory matter on bosons Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Bosons and Fermions (capsule reminder) Examples of bosons Examples of bosons (extension of the table) Digression: How a complex particle, like an atom, can behave as a single whole, a boson Digression: How a complex particle, like an atom, can behave as a single whole, a boson Digression: How a complex particle, like an atom, can behave as a single whole, a boson Plane waves in a cavity Density of states Ideal quantum gases at a finite temperature Ideal quantum gases at a finite temperature Ideal quantum gases at a finite temperature Ideal quantum gases at a finite temperature The Planck formula for black-body radiation Equilibrium radiation in a cavity Planck formula Stephan-Boltzmann law Stephan-Boltzmann law Stephan-Boltzmann law Stephan-Boltzmann law Stephan-Boltzmann law Bose-Einstein condensation: elementary approach Einstein's manuscript with the derivation of BEC What is the nature of BEC? A gas with a fixed average number of atoms A gas with a fixed average number of atoms A gas with a fixed average number of atoms A gas with a fixed average number of atoms A gas with a fixed average number of atoms A gas with a fixed average number of atoms Condensate concentration Condensate concentration Condensate concentration Condensate concentration Condensate concentration Digression: simple interpretation of T[C ]de Broglie wave length for atoms and molekules Ketterle explains BEC to the King of Sweden Condensate concentration Where are the condensate atoms? Where are the condensate atoms? Continuation Where are the condensate atoms? Summary Closer look at BEC Closer look at BEC Closer look at BEC Closer look at BEC Closer look at BEC Off-Diagonal Long Range Order Analysis on the one-particle level Coherence in BEC: ODLRO Coherence in BEC: ODLRO Coherence in BEC: ODLRO Coherence in BEC: ODLRO Coherence in BEC: ODLRO OPDM for homogeneous systems OPDM for homogeneous systems: ODLRO OPDM for homogeneous systems: ODLRO OPDM for homogeneous systems: ODLRO From OPDM towards the macroscopic wave function From OPDM towards the macroscopic wave function From OPDM towards the macroscopic wave function F.Laloë: Do we really understand Quantum mechanics, Am.J.Phys.69, 655 (2001) The end Problems