Cold Quantum Fluids (CQF)

Sam Carr

Quantum fluids are those many-particle systems in whose behaviour the effects of both the quantum mechanics and quantum statistics are important. They range from atoms and molecules, such as liquid Helium 4He and 3He and dilute atomic alkali gases, photons interacting via coupling to some matter component to electrons in metals and other solid state quasiparticles such as excitons, polaritons and magnons. In these lectures we explore collective properties of such systems. We begin by discussing the principal quantum collective phenomenon, which lies at the heart of many related concepts, that of a Bose-Einstein condensation in bosonic systems. We then progress to look at how fermions can cooperate to also “bose-condense” and how it is possible to cross from “fermionic” to “bosonic” condensates by changing particle density and/or interaction strength – the BCS-BEC crossover. We then discuss one of the most exciting manifestations of many particle quantum collective behaviour that of superfluidity. We also review physical experimental systems focusing on ultra-cold atomic gases, excitons and polaritons, and interacting photons in various settings. We closes the course with a short discussion of strongly interacting quantum systems such as atoms in optical lattices and coupled cavity lattices.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.

Cold Quantum Fluids (CQF)

Sam Carr

Quantum fluids are those many-particle systems in whose behaviour the effects of both the quantum mechanics and quantum statistics are important. They range from atoms and molecules, such as liquid Helium 4He and 3He and dilute atomic alkali gases, photons interacting via coupling to some matter component to electrons in metals and other solid state quasiparticles such as excitons, polaritons and magnons. In these lectures we explore collective properties of such systems. We begin by discussing the principal quantum collective phenomenon, which lies at the heart of many related concepts, that of a Bose-Einstein condensation in bosonic systems. We then progress to look at how fermions can cooperate to also “bose-condense” and how it is possible to cross from “fermionic” to “bosonic” condensates by changing particle density and/or interaction strength – the BCS-BEC crossover. We then discuss one of the most exciting manifestations of many particle quantum collective behaviour that of superfluidity. We also review physical experimental systems focusing on ultra-cold atomic gases, excitons and polaritons, and interacting photons in various settings. We closes the course with a short discussion of strongly interacting quantum systems such as atoms in optical lattices and coupled cavity lattices.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.

Topological Phases of Matter (TOP)

Sam Carr

The well-known Landau theory of phase transitions classifies phases of matter according to broken symmetries and local order parameters, such as solids that break translational symmetry, or magnets that break magnetic rotation symmetry.  It has been long known that there are phases of matter that defy this classification — the quantum Hall state being the most obvious (but by no means only) example.  With the discovery of topological insulators about 10 years ago, interest in this field has exploded, and we now know of many distinct phases of matter with no local order parameter, but instead characterised by a topological invariant.  This short lecture course will focus mostly on non-interacting band theory, and introduce topological invariants, boundary states, and the bulk-boundary correspondence necessary to understand the modern topic of topological insulators.  Other manifestations of topology in modern condensed matter physics will also be exposed, although not discussed in detail.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.

Topological Phases of Matter (TOP)

Sam Carr

The well-known Landau theory of phase transitions classifies phases of matter according to broken symmetries and local order parameters, such as solids that break translational symmetry, or magnets that break magnetic rotation symmetry.  It has been long known that there are phases of matter that defy this classification — the quantum Hall state being the most obvious (but by no means only) example.  With the discovery of topological insulators about 10 years ago, interest in this field has exploded, and we now know of many distinct phases of matter with no local order parameter, but instead characterised by a topological invariant.  This short lecture course will focus mostly on non-interacting band theory, and introduce topological invariants, boundary states, and the bulk-boundary correspondence necessary to understand the modern topic of topological insulators.  Other manifestations of topology in modern condensed matter physics will also be exposed, although not discussed in detail.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.

Topological Phases of Matter (TOP)

Sam Carr

The well-known Landau theory of phase transitions classifies phases of matter according to broken symmetries and local order parameters, such as solids that break translational symmetry, or magnets that break magnetic rotation symmetry.  It has been long known that there are phases of matter that defy this classification — the quantum Hall state being the most obvious (but by no means only) example.  With the discovery of topological insulators about 10 years ago, interest in this field has exploded, and we now know of many distinct phases of matter with no local order parameter, but instead characterised by a topological invariant.  This short lecture course will focus mostly on non-interacting band theory, and introduce topological invariants, boundary states, and the bulk-boundary correspondence necessary to understand the modern topic of topological insulators.  Other manifestations of topology in modern condensed matter physics will also be exposed, although not discussed in detail.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.

Topological Phases of Matter (TOP)

Sam Carr

The well-known Landau theory of phase transitions classifies phases of matter according to broken symmetries and local order parameters, such as solids that break translational symmetry, or magnets that break magnetic rotation symmetry.  It has been long known that there are phases of matter that defy this classification — the quantum Hall state being the most obvious (but by no means only) example.  With the discovery of topological insulators about 10 years ago, interest in this field has exploded, and we now know of many distinct phases of matter with no local order parameter, but instead characterised by a topological invariant.  This short lecture course will focus mostly on non-interacting band theory, and introduce topological invariants, boundary states, and the bulk-boundary correspondence necessary to understand the modern topic of topological insulators.  Other manifestations of topology in modern condensed matter physics will also be exposed, although not discussed in detail.

Sam works on the theory of strongly correlated systems, specialising in low-dimensional systems both in and out of equilibrium. He has worked in groups in the US, Italy and Germany, and since 2013 has been a lecturer at the University of Kent in Canterbury.