Julian Sonner

Holographic superconductivity in M theory.

Using seven-dimensional Sasaki-Einstein spaces we construct solutions of D=11 supergravity that are holographically dual to superconductors in three spacetime dimensions. Our numerical results indicate a new zero temperature solution dual to a quantum critical point.

Quantum criticality and holographic superconductors in M-theory

We present a consistent Kaluza-Klein truncation of D = 11 supergravity on an arbitrary seven-dimensional Sasaki-Einstein space (SE7) to a D = 4 theory containing a metric, a gauge-field, a complex scalar field and a real scalar field. We use this D = 4 theory to construct various black hole solutions that describe the thermodynamics of the d = 3 CFTs dual to skew-whiffed AdS4 × SE7 solutions. We show that these CFTs have a rich phase diagram, including holographic superconductivity with, generically, broken parity and time reversal invariance. At zero temperature the superconducting solutions are charged domain walls with a universal emergent conformal symmetry in the far infrared.

Rotating holographic superconductor

In this paper we initiate the study of spontaneous symmetry breaking in 3+1 dimensional rotating, charged, asymptotically AdS black holes. The theory living on their boundary, RxS{sup 2}, has the interpretation of a 2+1 dimensional rotating holographic superconductor. We study the appearance of a marginal mode of the condensate as the temperature is decreased. We find that the transition temperature depends on the rotation. At temperatures just below T{sub c}, the transition temperature at zero rotation, there exists a critical value of the rotation, which destroys the superconducting order. This behavior is analogous to the emergence of a critical applied magnetic field and we show that the superconductor in fact produces the expected London field in the planar limit.

Holographic superfluids and the dynamics of symmetry breaking.

We explore the far-from-equilibrium response of a holographic superfluid using the AdS/CFT correspondence. We establish the dynamical phase diagram corresponding to quantum quenches of the order parameter source field. We find three distinct regimes of behavior that are related to the spectrum of black hole quasinormal modes. These correspond to damped oscillations of the order parameter and to overdamped approaches to the superfluid and normal states. The presence of three regimes, which includes an emergent dynamical temperature scale, is argued to occur more generally in time-reversal-invariant systems that display continuous symmetry breaking.

Gravity derivation of the Tisza-Landau model in AdS/CFT

We derive the fully backreacted bulk solution dual to a boundary superfluid with finite supercurrent density in AdS/CFT. The nonlinear boundary hydrodynamical description of this solution is shown to be governed by a relativistic version of the Tisza-Landau two-fluid model to nondissipative order. As previously noted, the phase transition can be both first order and second order, but in the strongly backreacted regime at low charge q we find that the transition remains second order for all allowed fractions of superfluid density.

Black Hole Collapse in the 1/c Expansion

A bstractWe present a first-principles CFT calculation corresponding to the spherical collapse of a shell of matter in three dimensional quantum gravity. In field theory terms, we describe the equilibration process, from early times to thermalization, of a CFT following a sudden injection of energy at time t = 0. By formulating a continuum version of Zamolodchikov’s monodromy method to calculate conformal blocks at large central charge c, we give a framework to compute a general class of probe observables in the collapse state, incorporating the full backreaction of matter fields on the dual geometry. This is illustrated by calculating a scalar field two-point function at time-like separation and the time-dependent entanglement entropy of an interval, both showing thermalization at late times. The results are in perfect agreement with previous gravity calculations in the AdS3-Vaidya geometry. Information loss appears in the CFT as an explicit violation of unitarity in the 1/c expansion, restored by nonperturbative corrections.

Holographic Schwinger effect and the geometry of entanglement.

We show that the recently proposed bulk dual of an entangled pair of a quark and an antiquark corresponds to the Lorentzian continuation of the tunneling instanton describing Schwinger pair creation in the dual field theory. This observation supports and further explains the claim by Jensen and Karch that the bulk dual of an Einstein-Podolsky-Rosen pair is a string with a wormhole on its world sheet. We suggest that this constitutes a holographically dual realization of the creation of a Wheeler wormhole.

Competing orders in M-theory: superfluids, stripes and metamagnetism

A bstractWe analyse the infinite class of d = 3 CFTs dual to skew-whiffed AdS4 × SE7 solutions of D = 11 supergravity at finite temperature and charge density and in the presence of a magnetic field. We construct black hole solutions corresponding to the unbroken phase, and at zero temperature some of these become dyonic domain walls of an Einstein-Maxwell-pseudo-scalar theory interpolating between AdS4 in the UV and new families of dyonic

Spectral function of the supersymmetry current

Ad{S_2}\times {{\mathbb{R}}^2}

Universal fermionic spectral functions from string theory.

solutions in the IR. The black holes exhibit both diamagnetic and paramagnetic behaviour. We analyse superfluid and striped instabilities and show that for large enough values of the magnetic field the superfluid instability disappears while the striped instability remains. For larger values of the magnetic field there is also a first-order metamagnetic phase transition and at zero temperature these black hole solutions exhibit hyperscaling violation in the IR with dynamical exponent z = 3/2 and θ = −2.