Triangle Seminars
Monday, 3 Jun 2019
Bimetric theory of fractional quantum Hall states
Andrey Gromov
(Brown U.)
Abstract:
Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the Girvin-MacDonald-Platzman (GMP) mode. Certain features of this mode are independent of the microscopic details. The objective of the talk is to construct an effective theory includes both topological properties and the massive GMP mode. The theory reproduces the universal properties of chiral lowest Landau level (LLL) FQH states which lie beyond the TQFT data, such as the projected static structure factor and the GMP algebra of area-preserving diffeomorphisms. The dynamics of the mode is described by a fluctuating rank-2 symmetric, positive-definite tensor, which leads to a natural geometric (or gravitational) interpretation of the GMP mode.
Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the Girvin-MacDonald-Platzman (GMP) mode. Certain features of this mode are independent of the microscopic details. The objective of the talk is to construct an effective theory includes both topological properties and the massive GMP mode. The theory reproduces the universal properties of chiral lowest Landau level (LLL) FQH states which lie beyond the TQFT data, such as the projected static structure factor and the GMP algebra of area-preserving diffeomorphisms. The dynamics of the mode is described by a fluctuating rank-2 symmetric, positive-definite tensor, which leads to a natural geometric (or gravitational) interpretation of the GMP mode.
Posted by: QMW
Tuesday, 4 Jun 2019
Bimetric theory of fractional quantum Hall states
Andrey Gromov
(Brown)
Abstract:
Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the Girvin-MacDonald-Platzman (GMP) mode. Certain features of this mode are independent of the microscopic details. The objective of the talk is to construct an effective theory includes both topological properties and the massive GMP mode. The theory reproduces the universal properties of chiral lowest Landau level (LLL) FQH states which lie beyond the TQFT data, such as the projected static structure factor and the GMP algebra of area-preserving diffeomorphisms. The dynamics of the mode is described by a fluctuating rank-2 symmetric, positive-definite tensor, which leads to a natural geometric (or gravitational) interpretation of the GMP mode.
Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the Girvin-MacDonald-Platzman (GMP) mode. Certain features of this mode are independent of the microscopic details. The objective of the talk is to construct an effective theory includes both topological properties and the massive GMP mode. The theory reproduces the universal properties of chiral lowest Landau level (LLL) FQH states which lie beyond the TQFT data, such as the projected static structure factor and the GMP algebra of area-preserving diffeomorphisms. The dynamics of the mode is described by a fluctuating rank-2 symmetric, positive-definite tensor, which leads to a natural geometric (or gravitational) interpretation of the GMP mode.
Posted by: IC
Wednesday, 5 Jun 2019
Black holes in N=4 Super-Yang-Mills
Francesco Benini
(SISSA)
Abstract:
AdS/CFT provides a consistent non-perturbative definition of quantum
gravity in asymptotically AdS space. Black holes should correspond to
ensembles of states in the boundary field theory. By analyzing the
superconformal index of 4d N=4 SU(N) Super-Yang-Mills, with the help
of a new Bethe Ansatz type formula, we are able to exactly reproduce
the Bekenstein-Hawking entropy of BPS black holes in AdS5 x S5. The
large N limit exhibits many competing contributions and Stokes
phenomena, hinting at new physics.
AdS/CFT provides a consistent non-perturbative definition of quantum
gravity in asymptotically AdS space. Black holes should correspond to
ensembles of states in the boundary field theory. By analyzing the
superconformal index of 4d N=4 SU(N) Super-Yang-Mills, with the help
of a new Bethe Ansatz type formula, we are able to exactly reproduce
the Bekenstein-Hawking entropy of BPS black holes in AdS5 x S5. The
large N limit exhibits many competing contributions and Stokes
phenomena, hinting at new physics.
Posted by: IC
Thursday, 6 Jun 2019
From the convergence and resummation of all-order hydrodynamics to quantum chaos
Saso Grozdanov
(MIT)
Abstract:
Hydrodynamic excitations corresponding to sound and diffusive modes in fluids are characterised by gapless dispersion relations. In the hydrodynamic gradient expansion, their frequencies are represented by infinite power series in spatial momenta. I will discuss how the introduction of a new concept of the hydrodynamic complex spectral curve in the space of complexified frequency and spatial momentum—the concept otherwise known from algebraic geometry–-can be used to prove general properties about hydrodynamics, including its finite radius of convergence. When the infinite series are resummed, they exhibit a fascinating, recently-discovered phenomenon of pole-skipping, which enables us to analyse the underlying, microscopic quantum many-body chaos in the system. Throughout my talk, I will use gauge-gravity duality as a tool to explicitly show these phenomena in holographic systems and discuss what their implications are for the dual gravity theory.
Hydrodynamic excitations corresponding to sound and diffusive modes in fluids are characterised by gapless dispersion relations. In the hydrodynamic gradient expansion, their frequencies are represented by infinite power series in spatial momenta. I will discuss how the introduction of a new concept of the hydrodynamic complex spectral curve in the space of complexified frequency and spatial momentum—the concept otherwise known from algebraic geometry–-can be used to prove general properties about hydrodynamics, including its finite radius of convergence. When the infinite series are resummed, they exhibit a fascinating, recently-discovered phenomenon of pole-skipping, which enables us to analyse the underlying, microscopic quantum many-body chaos in the system. Throughout my talk, I will use gauge-gravity duality as a tool to explicitly show these phenomena in holographic systems and discuss what their implications are for the dual gravity theory.
Posted by: QMW