24 research outputs found
The Plane-Wave/Super Yang-Mills Duality
We present a self-contained review of the Plane-wave/super-Yang-Mills
duality, which states that strings on a plane-wave background are dual to a
particular large R-charge sector of N=4, D=4 superconformal U(N) gauge theory.
This duality is a specification of the usual AdS/CFT correspondence in the
"Penrose limit''. The Penrose limit of AdS_5 S^5 leads to the maximally
supersymmetric ten dimensional plane-wave (henceforth "the'' plane-wave) and
corresponds to restricting to the large R-charge sector, the BMN sector, of the
dual superconformal field theory. After assembling the necessary background
knowledge, we state the duality and review some of its supporting evidence. We
review the suggestion by 't Hooft that Yang-Mills theories with gauge groups of
large rank might be dual to string theories and the realization of this
conjecture in the form of the AdS/CFT duality. We discuss plane-waves as exact
solutions of supergravity and their appearance as Penrose limits of other
backgrounds, then present an overview of string theory on the plane-wave
background, discussing the symmetries and spectrum. We then make precise the
statement of the proposed duality, classify the BMN operators, and mention some
extensions of the proposal. We move on to study the gauge theory side of the
duality, studying both quantum and non-planar corrections to correlation
functions of BMN operators, and their operator product expansion. The important
issue of operator mixing and the resultant need for re-diagonalization is
stressed. Finally, we study strings on the plane-wave via light-cone string
field theory, and demonstrate agreement on the one-loop correction to the
string mass spectrum and the corresponding quantity in the gauge theory. A new
presentation of the relevant superalgebra is given.Comment: RevTeX 4 format; 91 pages; 7 figures. Prepared for Reviews of Modern
Physics. Please send comments to darius, jabbari @ itp.stanford.edu. v3:
Minor typos fixe
Stochastic Differential Equations for Quantum Dynamics of Spin-Boson Networks
The quantum dynamics of open many-body systems poses a challenge for
computational approaches. Here we develop a stochastic scheme based on the
positive P phase-space representation to study the nonequilibrium dynamics of
coupled spin-boson networks that are driven and dissipative. Such problems are
at the forefront of experimental research in cavity and solid state
realizations of quantum optics, as well as cold atom physics, trapped ions and
superconducting circuits. We demonstrate and test our method on a driven,
dissipative two-site system, each site involving a spin coupled to a photonic
mode, with photons hopping between the sites, where we find good agreement with
Monte Carlo Wavefunction simulations. In addition to numerically reproducing
features recently observed in an experiment [Phys. Rev. X 4, 031043 (2014)], we
also predict a novel steady state quantum dynamical phase transition for an
asymmetric configuration of drive and dissipation.Comment: 15 pages, 8 figure
Beyond Strong Coupling in a Massively Multimode Cavity
The study of light-matter interaction has seen a resurgence in recent years,
stimulated by highly controllable, precise, and modular experiments in cavity
quantum electrodynamics (QED). The achievement of strong coupling, where the
coupling between a single atom and fundamental cavity mode exceeds the decay
rates, was a major milestone that opened the doors to a multitude of new
investigations. Here we introduce multimode strong coupling (MMSC), where the
coupling is comparable to the free spectral range (FSR) of the cavity, i.e. the
rate at which a qubit can absorb a photon from the cavity is comparable to the
round trip transit rate of a photon in the cavity. We realize, via the circuit
QED architecture, the first experiment accessing the MMSC regime, and report
remarkably widespread and structured resonance fluorescence, whose origin
extends beyond cavity enhancement of sidebands. Our results capture complex
multimode, multiphoton processes, and the emergence of ultranarrow linewidths.
Beyond the novel phenomena presented here, MMSC opens a major new direction in
the exploration of light-matter interactions.Comment: 14 pages, 11 figures. References added, typos correcte
Statistics, Condensation and the Anderson-Higgs Mechanism: The Worldline Path Integral View
We explain, in the first quantized path integral formalism, the mechanism
behind the Anderson-Higgs effect for a gas of charged bosons in a background
magnetic field, and then use the method to prove the absence of the effect for
a gas of fermions. The exchange statistics are encoded via the inclusion of
additional Grassmann coordinates in a manner that leads to a manifest worldline
supersymmetry. This extra symmetry is key in demonstrating the absence of the
effect for charged fermions.Comment: 10 pages, no figures; typos correcte