Three-dimensional Quantum Electrodynamics Research Articles

Critical Properties of Three-Dimensional Many-Flavor QEDs

We review several variants of three-dimensional quantum electrodynamics (QED3) with Nf fermion (or boson) flavors, including fermionic (or spinorial) QED3, bosonic (or scalar) QED3, N=1 supersymmetric QED and also models of reduced QED (supersymmetric or not). We begin with an introduction to these models and their flow to a stable infra-red fixed point in the large-Nf limit. We then present detailed state-of-the-art computations of the critical exponents of these models within the dimensional regularization (and reduction) scheme(s), at the next-to-leading order in the 1/Nf expansion and in an arbitrary covariant gauge. We finally discuss dynamical (matter) mass generation and the current status of our understanding of the phase structure of these models.

Quasimonoenergetic Proton Acceleration via Quantum Radiative Compression

Dense high-energy monoenergetic proton beams are vital for wide applications, thus modern laser-plasma-based ion-acceleration methods are aiming to obtain high-energy proton beams with energy spread as low as possible. In this work, we put forward a quantum radiative compression method to postcompress a highly accelerated proton beam and convert it to a dense quasimonoenergetic one. We find that when the relativistic plasma produced by radiation-pressure acceleration collides head on with an ultraintense laser beam, large-amplitude plasma oscillations are excited due to quantum radiation reaction and the ponderomotive force, which induce compression of the phase space of protons located in its acceleration phase with negative gradient. Our three-dimensional spin-resolved quantum electrodynamics (QED) particle-in-cell simulations show that hollow-structure proton beams with a peak energy approximately $\mathrm{GeV}$, relative energy spread of few percents, and number ${N}_{p}\ensuremath{\sim}{10}^{10}$ (or ${N}_{p}\ensuremath{\sim}{10}^{9}$ with a $1\mathrm{%}$ energy spread) can be produced in near-future laser facilities, which may fulfill the requirements of alternative applications, such as, for radiography of ultrathick dense materials, or as injectors of hadron colliders.

Gamma-ray flash generation in irradiating a thin foil target by a single-cycle tightly focused extreme power laser pulse.

We present a regime where an ultraintense laser pulse interacting with a foil target results in high γ-photon conversion efficiency, obtained via three-dimensional quantum-electrodynamics particle-in-cell simulations. A single-cycle laser pulse is used under the tight-focusing condition for obtaining the λ^{3} regime. The simulations employ a radially polarized laser as it results in higher γ-photon conversion efficiency compared to both azimuthal and linear polarizations. A significant fraction of the laser energy is transferred to positrons, while a part of the electromagnetic wave escapes the target as attosecond single-cycle pulses.

Confinement transition in the QED3 -Gross-Neveu-XY universality class

The coupling between fermionic matter and gauge fields plays a fundamental role in our understanding of nature, while at the same time posing a challenging problem for theoretical modeling. In this situation, controlled information can be gained by combining different complementary approaches. Here, we study a confinement transition in a system of $N_f$ flavors of interacting Dirac fermions charged under a U(1) gauge field in 2+1 dimensions. Using Quantum Monte Carlo simulations, we investigate a lattice model that exhibits a continuous transition at zero temperature between a gapless deconfined phase, described by three-dimensional quantum electrodynamics, and a gapped confined phase, in which the system develops valence-bond-solid order. We argue that the quantum critical point is in the universality class of the QED$_3$-Gross-Neveu-XY model. We study this field theory within a $1/N_f$ expansion in fixed dimension as well as a renormalization group analysis in $4-\epsilon$ space-time dimensions. The consistency between numerical and analytical results is revealed from large to intermediate flavor number.

Lorentz symmetry breaking in supersymmetric quantum electrodynamics

Lorentz symmetry is one of the fundamental symmetries of nature; however, it can be broken by several proposals such as quantum gravity effects, low energy approximations in string theory and dark matter. In this paper, Lorentz symmetry is broken in supersymmetric quantum electrodynamics using aether superspace formalism without breaking any supersymmetry. To break the Lorentz symmetry in three-dimensional quantum electrodynamics, we must use the [Formula: see text] aether superspace. A new constant vector field is introduced and used to deform the deformed generator of supersymmetry. This formalism is required to fix the unphysical degrees of freedom that arise from the quantum gauge transformation required to quantize this theory. By using Yokoyama’s gaugeon formalism, it is possible to study these gaugeon transformations. As a result of the quantum gauge transformation, the supersymmetric algebra gets modified and the theory is invariant under BRST symmetry. These results could aid in the construction of the Gravity’s Rainbow theory and in the study of superconformal field theory. Furthermore, it is demonstrated that different gauges in this deformed supersymmetric quantum electrodynamics can be related to each other using the gaugeon formalism.

Laser-driven vacuum breakdown waves

It is demonstrated by three-dimensional quantum electrodynamics — particle-in-cell (QED-PIC) simulations that vacuum breakdown wave in the form of QED cascade front can propagate in an extremely intense plane electromagnetic wave. The result disproves the statement that the self-sustained cascading is not possible in a plane wave configuration. In the simulations the cascade is initiated during laser-foil interaction in the light sail regime. As a result, a constantly growing electron-positron plasma cushion is formed between the foil and laser radiation. The cushion plasma efficiently absorbs the laser energy and decouples the radiation from the moving foil thereby interrupting the ion acceleration. The models describing propagation of the cascade front and electrodynamics of the cushion plasma are presented and their predictions are in a qualitative agreement with the results of numerical simulations.

Effects of random potentials in three-dimensional quantum electrodynamics

Three-dimensional quantum electrodynamics exhibits a number of interesting properties, such as dynamical chiral symmetry breaking, weak confinement, and non-Fermi liquid behavior, and also has wide applications in condensed matter physics. We study the effects of random potentials, which exist in almost all realistic condensed-matter systems, on the low-energy behaviors of massless Dirac fermions by means of renormalization group method, and show that the role of random mass is significantly enhanced by the gauge interaction, whereas random scalar and vector potentials are insusceptible to the gauge interaction at the one-loop order. The static random potential breaks the Lorentz invariance, and as such induces unusual renormalization of fermion velocity. We then consider the case in which three types of random potentials coexist in the system. The random scalar potential is found to play a dominant role in the low-energy region, and drives the system to undergo a quantum phase transition.

Monopole operators from the 4 − ϵ expansion

Three-dimensional quantum electrodynamics with $N$ charged fermions contains monopole operators that have been studied perturbatively at large $N$. Here, we initiate the study of these monopole operators in the $4-\epsilon$ expansion by generalizing them to codimension-3 defect operators in $d = 4-\epsilon$ spacetime dimensions. Assuming the infrared dynamics is described by an interacting CFT, we define the "conformal weight" of these operators in terms of the free energy density on $S^2 \times \mathbb{H}^{2-\epsilon}$ in the presence of magnetic flux through the $S^2$, and calculate this quantity to next-to-leading order in $\epsilon$. Extrapolating the conformal weight to $\epsilon = 1$ gives an estimate of the scaling dimension of the monopole operators in $d=3$ that does not rely on the $1/N$ expansion. We also perform the computation of the conformal weight in the large $N$ expansion for any $d$ and find agreement between the large $N$ and the small $\epsilon$ expansions in their overlapping regime of validity.

Generation of gamma-ray beam with orbital angular momentum in the QED regime

We propose a scheme to generate high-energy gamma-ray photons with an orbital angular momentum (OAM) from laser-plasma interactions by irradiating a circularly polarized Laguerre–Gaussian laser on a thin plasma target. The spin angular momentum and OAM are first transferred to electrons from the driving laser, and then the OAM is transferred to the gamma-ray photons from the electrons through quantum radiation. This scheme has been demonstrated by using three-dimensional quantum electrodynamics particle-in-cell simulations. The topological charge, chirality, and carrier-envelope phase of the short ultra-intense vortex laser can be revealed according to the energy distribution of gamma-ray emission.

Chiral symmetry breaking in three-dimensional quantum electrodynamics as fixed point annihilation

Spontaneous chiral symmetry breaking in three dimensional ($d=3$) quantum electrodynamics is understood as annihilation of an infrared-stable fixed point that describes the large-N conformal phase by another unstable fixed point at a critical number of fermions $N=N_c$. We discuss the root of universality of $N_c$ in this picture, together with some features of the phase boundary in the $(d,N)$ plane. In particular, it is shown that as $d\rightarrow 4$, $N_c\rightarrow 0$ with a constant slope, our best estimate of which suggests that $N_c = 2.89$ in $d=3$.

Multilayer microwave integrated quantum circuits for scalable quantum computing

AbstractAs experimental quantum information processing (QIP) rapidly advances, an emerging challenge is to design a scalable architecture that combines various quantum elements into a complex device without compromising their performance. In particular, superconducting quantum circuits have successfully demonstrated many of the requirements for quantum computing, including coherence levels that approach the thresholds for scaling. However, it remains challenging to couple a large number of circuit components through controllable channels while suppressing any other interactions. We propose a hardware platform intended to address these challenges, which combines the advantages of integrated circuit fabrication and the long coherence times achievable in three-dimensional circuit quantum electrodynamics. This multilayer microwave integrated quantum circuit platform provides a path towards the realisation of increasingly complex superconducting devices in pursuit of a scalable quantum computer.

Renormalization of fermion velocity in finite temperatureQED3

At zero temperature, the Lorentz invariance is strictly preserved in three-dimensional quantum electrodynamics. This property ensures that the velocity of massless fermions is not renormalized by the gauge interaction. At finite temperature, however, the Lorentz invariance is explicitly broken by the thermal fluctuation. The longitudinal component of gauge interaction becomes short-ranged due to thermal screening, whereas the transverse component remains long-ranged because of local gauge invariance. The transverse gauge interaction leads to singular corrections to the fermion self-energy and thus results in an unusual renormalization of the fermion velocity. We calculate the renormalized fermion velocity $v^R(p_0,\mathbf{p},T)$ by employing a renormalization group analysis, and discuss the influence of the anomalous dimension $\eta_n$ on the fermion specific heat.

The effect of nonlinear quantum electrodynamics on relativistic transparency and laser absorption in ultra-relativistic plasmas

With the aid of large-scale three-dimensional quantum electrodynamics (QED)-particle-in-cell simulations, we describe a potential experimental configuration to measure collective effects that couple strong field QED to plasma kinetics and develop a simple analytic model that describes the absorption due to radiation emission. For two counter propagating lasers interacting with a foil at intensities exceeding W cm−2, a near-binary result occurs; when quantum effects are included, a foil that classically would effectively transmit the laser pulse becomes opaque. This is a dramatic change in plasma behavior, directly as a consequence of the coupling of radiation reaction and pair production to plasma dynamics.

Determine the critical fermion flavor in three-dimensional QED using nonlocal gauge

We determine the critical fermion flavor for dynamical chiral symmetry breaking in three-dimensional quantum electrodynamics using nonlocal gauge (gauge parameter depends on the momentum or coordinate). The coupled Dyson–Schwinger equations of the fermion and gauge boson propagators are considered in the vicinity of the critical point. Illustrated by using the transverse vertex proposed by Bashir et al., we show that: for a variety of the transverse vertex, the critical flavor is still 128/3π2, the same as using the bare vertex.

Three-dimensional cavity quantum electrodynamics with a rare-earth spin ensemble

We present cavity QED experiments with an Er:YSO crystal magnetically coupled to a 3D cylindrical sapphire loaded copper resonator. Such waveguide cavities are promising for the realization of a superconducting quantum processor. Here, we demonstrate the coherent integration of a rare-earth spin ensemble with the 3D architecture. The collective coupling strength of the Er$^{3+}$ spins to the 3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to explore the anisotropic collective coupling between the rare-earth doped crystal and the cavity. This work shows the potential of spin doped solids in 3D quantum circuits for application as microwave quantum memories as well as for prospective microwave to optical interfaces.

Two-loop fermion self-energy in reduced quantum electrodynamics and application to the ultrarelativistic limit of graphene

We compute the two-loop fermion self-energy in massless reduced quantum electrodynamics for an arbitrary gauge using the method of integration by parts. Focusing on the limit where the photon field is four-dimensional, our formula involves only recursively one-loop integrals and can therefore be evaluated exactly. From this formula, we deduce the anomalous scaling dimension of the fermion field as well as the renormalized fermion propagator up to two loops. The results are then applied to the ultra-relativistic limit of graphene and compared with similar results obtained for four-dimensional and three-dimensional quantum electrodynamics.

Anomalous dimensions of monopole operators in three-dimensional quantum electrodynamics

The space of local operators in three-dimensional quantum electrodynamics contains monopole operators that create $n$ units of gauge flux emanating from the insertion point. This paper uses the state-operator correspondence to calculate the anomalous dimensions of these monopole operators perturbatively to next-to-leading order in the $1/{N}_{f}$ expansion, thus improving on the existing leading-order results in the literature. Here, ${N}_{f}$ is the number of two-component complex fermion flavors. The scaling dimension of the $n=1$ monopole operator is $0.265{N}_{f}\ensuremath{-}0.0383+O(1/{N}_{f})$ at the infrared conformal fixed point.

Topological quantum phase transition in Kane-Mele-Kondo lattice model

We systematically explore the ground-state phase diagram of the Kane-Mele-Kondo lattice model on the honeycomb lattice, in particular, we focus on its magnetic properties which has not been studied in the previous publication[Feng, Dai, Chung, and Si, Phys. Rev. Lett. \textbf{111}, 016402 (2013)]. Beside the Kondo insulator found in that paper, two kinds of antiferromagnetic spin-density-wave phases are identified. One is the normal antiferromagnetic spin-density-wave state and the other is a nontrivial topological antiferromagnetic spin-density-wave state with a quantized spin Hall conductance and a helical edge-state. The quantum spin Hall insulator is found to be absent since it is always unstable to antiferromagnetic spin-density-wave states at least at the mean-field level in our model. Furthermore, the transition between the two spin-density-wave phases are topological quantum phase transition described by the three-dimensional quantum electrodynamics, in which conduction electrons contribute to the low-energy Dirac fermions while the spin-wave fluctuation of local spins gives rise to an effective dynamic U(1) gauge-field. Such nontrivial transition shows radical critical thermodynamic, transport and single-particle behaviors, which provide a fingerprint for this transition. Additionally, the transition of antiferromagnetic spin-density-wave states to the Kondo insulator is found to be first-order. The introduction of two novel magnetic phases and their topological quantum phase transition show rich and intrinsic physics involving in the Kane-Mele-Kondo lattice model.

Chern-Simons terms in Lifshitz-like quantum electrodynamics

In this work the generation of generalized Chern-Simons terms in three-dimensional quantum electrodynamics with high spatial derivatives is studied. We analyze the self-energy corrections to the gauge field propagator by considering an expansion of the corresponding amplitudes up to third order in the external momenta. The divergences of the corrections are determined and explicit forms for the Chern-Simons terms with high derivatives are obtained. Some unusual aspects of the calculation are stressed and the existence of a smooth isotropic limit is proved. The transversality of the anisotropic gauge propagator is also discussed.

Chiral phase diagram inQED3

We study the dynamical chiral symmetry breaking of three-dimensional quantum electrodynamics (${\mathrm{QED}}_{3}$) at finite temperature and chemical potential in the leading order of Dyson-Schwinger equation approach. After considering the chemical potential dependence of the boson propagator, we derive the expression for the boson polarization and then obtain the corresponding chiral phase diagram in the ($T\mathrm{\text{\ensuremath{-}}}\ensuremath{\mu}$) plane. A comparison between the phase diagram obtained above and the one obtained without considering the chemical potential dependence of the boson propagator is made. It is found that in a self-consistent study of the chiral phase diagram of ${\mathrm{QED}}_{3}$, the chemical potential dependence of the boson propagator cannot be neglected.