Soft modes in $ \mathcal{N} $ = 2 SYK model
We study various properties of the soft modes in the $ \mathcal{N} $ = 2 supersymmetric SYK model.
1/N expansion↗
Engineering topics
Peng, Cheng
Publications and source records attributed to Peng, Cheng.
Anatomy of deconfinement
In the weak coupling limit of ${\rm SU}(N)$ Yang-Mills theory and the ${\rm O}(N)$ vector model, explicit state counting allows us to demonstrate the existence of a partially deconfined phase: $M$ of $N$ colors deconfine, and $\frac{M}{N}$ gradually grows from zero (confinement) to one (complete deconfinement). We point out that the mechanism admits a simple interpretation in the form of spontaneous breaking of gauge symmetry. In terms of the dual gravity theory, such breaking occurs during the formation of a black hole. We speculate whether the breaking and restoration of gauge symmetry can serve as an alternative definition of the deconfinement transition in theories without center symmetry, such as QCD. We also discuss the role of the color degrees of freedom in the emergence of the bulk geometry in holographic duality.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Chiral algebras of two-dimensional SYK models
We study chiral algebras in the $\bar{Q}$-cohomology of two dimensional SYK models with extended supersymmetry. In a special limit discovered in [1], we are able to construct explicitly a “vertical” single-particle higher-spin algebra that is bilinear in the fundamental fields. This algebra can be regarded as the counterpart, when going away from criticality, of the infrared emergent higher-spin symmetry of the N=(0,2) SYK model. Moreover, a second “horizontal” single-particle higher-spin algebra appears in this limit. Together with the vertical algebra they generate a stringy algebra with a “higher spin square” structure that is believed to appear in the tensionless limit of string theory. On the other hand, we do not find single-particle higher-spin algebra away from the special limit, which is consistent with the result in [1]. Our analysis is carried out for each individual realization of the random couplings and for finite N (and M), which in particular indicates that the conclusion in [1] is robust to 1/N corrections.
1/N expansion↗
Thermal radiation control from hot graphene electrons coupled to a photonic crystal nanocavity
Controlling thermal radiation is central in a range of applications including sensing, energy harvesting, and lighting. The thermal emission spectrum can be strongly modified through the electromagnetic local density of states (EM LDOS) in nanoscale-patterned metals and semiconductors. However, these materials become unstable at high temperature, preventing improvements in radiative efficiency and applications such as thermophotovoltaics. Here, we report stable high-temperature thermal emission based on hot electrons (>2000 K) in graphene coupled to a photonic crystal nanocavity, which strongly modifies the EM LDOS. The electron bath in graphene is highly decoupled from lattice phonons, allowing a comparatively cool temperature (700 K) of the photonic crystal nanocavity. This thermal decoupling of hot electrons from the LDOS-engineered substrate opens a broad design space for thermal emission control that would be challenging or impossible with heated nanoscale-patterned metals or semiconductor materials.
14 SOLAR ENERGY↗
$\mathcal{N}=\left(0, 2\right)$ SYK, chaos and higher-spins
We study a 2-dimensional SYK-like model with \( \mathcal{N}=\left(0,\ 2\right) \) supersymmetry. The model describes N chiral supermultiplets and M Fermi supermultiplets with a ( q + 1)- field interaction. We solve the model analytically and numerically in the N $\gg$ 1, M $\gg$ 1 limit with \( \mu \equiv \frac{M}{N} \) being a free parameter. Two distinct higher-spin symmetries emerge when the μ parameter approaches the two ends of its range. This is verified by the appearance of conserved higher-spin operators and the vanishing of chaotic behaviors in the two limits. Therefore this model provides a manifest realization of the widely believed connection between SYK-like models and higher-spin theories. In addition, as the parameter μ varies we find the largest Lyapunov exponent of this model to be slightly larger than that in models with non-chiral supersymmetry.
1/N Expansion↗
Twin-plane-partitions and $\mathcal{N}$ = 2 affine Yangian
The universal enveloping algebra of W 1+∞ is isomorphic to the affine Yangian of $\mathfrak{g}{\mathfrak{l}}_1$. We study the N = 2 supersymmetric version of this correspondence, and identify the full set of defining relations of the supersymmetric affine Yangian. These relations can be deduced by demanding that the algebra has a representation on twin-plane-partitions, which we construct by gluing pairs of plane partitions. We define the action of the algebra on these twin-plane-partitions explicitly
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Fast thermal relaxation in cavity-coupled graphene bolometers with a Johnson noise read-out
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solar (photovoltaic), solid state lighting, photos↗
The supersymmetric affine Yangian
The affine Yangian of gl 1 is known to be isomorphic to W 1+∞ , the W-algebra that characterizes the bosonic higher spin — CFT duality. In this paper we propose some of the defining relations of the Yangian that are relevant for the N = 2 superconformal version of W 1+∞ . Our construction is based on the observation that the N = 2 superconformal W 1+∞ algebra contains two commuting bosonic W 1+∞ algebras, and that the additional generators transform in bi-minimal representations with respect to these two algebras. As a result, the corresponding affine Yangian can therefore be built up from two affine Yangians of gl 1 by adding in generators that transform appropriately.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Probing the ultimate plasmon confinement limits with a van der Waals heterostructure
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solar (photovoltaic), solid state lighting, photos↗
Correlators in the $ \mathcal{N}=2 $ supersymmetric SYK model
We study correlation functions in the one-dimensional $ \mathcal{N}=2 $ supersymmetric SYK model. The leading order 4-point correlation functions are computed by summing over ladder diagrams expanded in a suitable basis of conformal eigenfunctions. A novelty of the $ \mathcal{N}=2 $ model is that both symmetric and antisymmetric eigenfunctions are required. Although we use a component formalism, we verify that the operator spectrum and 4-point functions are consistent with $ \mathcal{N}=2 $ supersymmetry. Here, we also confirm the maximally chaotic behavior of this model and comment briefly on its 6-point functions.
1/N Expansion↗
Vector models and generalized SYK models
Here, we consider the relation between SYK-like models and vector models by studying a toy model where a tensor field is coupled with a vector field. By integrating out the tensor field, the toy model reduces to the Gross-Neveu model in 1 dimension. On the other hand, a certain perturbation can be turned on and the toy model flows to an SYK-like model at low energy. Furthermore, a chaotic-nonchaotic phase transition occurs as the sign of the perturbation is altered. We further study similar models that possess chaos and enhanced reparameterization symmetries.
1/N Expansion↗
A supersymmetric SYK-like tensor model
We consider a supersymmetric SYK-like model without quenched disorder that is built by coupling two kinds of fermionic Ν = 1 tensor-valued superfields, ''quarks'' and ''mesons''. We prove that the model has a well-defined large-N limit in which the (s)quark 2-point functions are dominated by mesonic ''melon'' diagrams. We sum these diagrams to obtain the Schwinger-Dyson equations and show that in the IR, the solution agrees with that of the supersymmetric SYK model.
1/N Expansion↗
Higher spins and Yangian symmetries
The relation between the bosonic higher spin W∞[λ]W∞[λ] algebra, the affine Yangian of gl 1 , and the SH c algebra is established in detail. For generic λ we find explicit expressions for the low-lying W∞[λ] modes in terms of the affine Yangian generators, and deduce from this the precise identification between λ and the parameters of the affine Yangian. Furthermore, for the free field cases corresponding to λ = 0 and λ = 1 we give closed-form expressions for the affine Yangian generators in terms of the free fields. Interestingly, the relation between the W∞ modes and those of the affine Yangian is a non-local one, in general. We also establish the explicit dictionary between the affine Yangian and the SH c generators. Lastly, given that Yangian algebras are the hallmark of integrability, these identifications should pave the way towards uncovering the relation between the integrable and the higher spin symmetries.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Active 2D materials for on-chip nanophotonics and quantum optics
Two-dimensional materials have emerged as promising candidates to augment existing optical networks for metrology, sensing, and telecommunication, both in the classical and quantum mechanical regimes. Here, we review the development of several on-chip photonic components ranging from electro-optic modulators, photodetectors, bolometers, and light sources that are essential building blocks for a fully integrated nanophotonic and quantum photonic circuit.
2D materials↗
Self-Aligned Local Electrolyte Gating of 2D Materials for Mid-Infrared Photodetection
We present a new gating concept based on a self-aligned electrolyte technique that can enable spatially modulating charges with nanometer resolution. We use this technique to demonstrate a graphene mid-infrared thermopile photodetector with novel geometry.
36 MATERIALS SCIENCE↗
Direction-Controlled Light-Driven Movement of Microribbons
Novel direction-controlled movements of microribbons self-assembled from perylene diimide molecules are reported on various hydrophobic surfaces under scanning laser irradiation. A “dynamic exciton charge model” is developed to elucidate the underlying mechanism. The findings provide an innovative strategy for the design of microscale systems capable of continuous and directional movement driven by light.
36 MATERIALS SCIENCE↗
Higgsing the stringy higher spin symmetry
It has recently been argued that the symmetric orbifold theory of T 4 is dual to string theory on AdS 3 × S 3 × T 4 at the tensionless point. At this point in moduli space, the theory possesses a very large symmetry algebra that includes, in particular, a W ∞ algebra capturing the gauge fields of a dual higher spin theory. Using conformal perturbation theory, we study the behaviour of the symmetry generators of the symmetric orbifold theory under the deformation that corresponds to switching on the string tension. We show that the generators fall nicely into Regge trajectories, with the higher spin fields corresponding to the leading Regge trajectory. We also estimate the form of the Regge trajectories for large spin, and find evidence for the familiar logarithmic behaviour, thereby suggesting that the symmetric orbifold theory is dual to an AdS background with pure RR flux.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗