scholarly journals Topological phases of quantized light

2020 ◽  
Author(s):  
Han Cai ◽  
Da-Wei Wang
Keyword(s):  
Annihilation Operator ◽  
Research Area ◽  
Honeycomb Structure ◽  
Two Dimensions ◽  
Topological Phases ◽  
Fock States ◽  
Haldane Model ◽  
Fock State ◽  
Topological States ◽  
Coupling Strengths

Abstract Topological photonics is an emerging research area that focuses on the topological states of classical light. Here we reveal the topological phases that are intrinsic to the quantum nature of light, i.e., solely related to the quantized Fock states and the inhomogeneous coupling strengths between them. The Hamiltonian of two cavities coupled with a two-level atom is an intrinsic one-dimensional Su-Schriefer-Heeger model of Fock states. By adding another cavity, the Fock-state lattice is extended to two dimensions with a honeycomb structure, where the strain due to the inhomogeneous coupling strengths of the annihilation operator induces a Lifshitz topological phase transition between a semimetal and three band insulators within the lattice. In the semimetallic phase, the strain is equivalent to a pseudomagnetic field, which results in the quantization of the Landau levels and the valley Hall effect. We further construct an inhomogeneous Fock-state Haldane model where the topological phases can be characterized by the topological markers. With d cavities being coupled to the atom, the lattice is extended to d − 1 dimensions without an upper limit. This study demonstrates a fundamental distinction between the topological phases in quantum and classical optics and provides a novel platform for studying topological physics in dimensions higher than three.

scholarly journals Electrically tunable low-density superconductivity in a monolayer topological insulator

Science ◽  
2018 ◽  
Vol 362 (6417) ◽  
pp. 926-929 ◽  
Author(s):  
Valla Fatemi ◽  
Sanfeng Wu ◽  
Yuan Cao ◽  
Landry Bretheau ◽  
Quinn D. Gibson ◽  
...  
Keyword(s):  
Ground State ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Quantum Spin ◽  
Topological Phases ◽  
Critical Temperatures ◽  
Topological States ◽  
Effect Transistor ◽  
Topological Phases Of Matter

Turning on superconductivity in a topologically nontrivial insulator may provide a route to search for non-Abelian topological states. However, existing demonstrations of superconductor-insulator switches have involved only topologically trivial systems. Here we report reversible, in situ electrostatic on-off switching of superconductivity in the recently established quantum spin Hall insulator monolayer tungsten ditelluride (WTe2). Fabricated into a van der Waals field-effect transistor, the monolayer’s ground state can be continuously gate-tuned from the topological insulating to the superconducting state, with critical temperaturesTcup to ~1 kelvin. Our results establish monolayer WTe2as a material platform for engineering nanodevices that combine superconducting and topological phases of matter.

Comparing Consumer Purchase Behavior on the Internet and in Brick-and-Mortar Stores

2001 ◽  
pp. 218-230
Author(s):  
Jie Zhang
Keyword(s):  
Research Area ◽  
Two Dimensions ◽  
Marketing Strategies ◽  
Purchase Behavior ◽  
Future Research ◽  
The Internet ◽  
Behavioral Differences ◽  
Shopping Environments ◽  
Brick And Mortar ◽  
Recent Developments

A research area that has gained interest of marketing researchers in recent years is the comparison of consumer behavior on the Internet and traditional brick-and-mortar stores. We offer an overview of the recent developments in this research area and summarize the key findings along two dimensions: 1) factors that may cause behavioral differences in the two types of shopping environments; and 2) patterns of behavioral differences identified in the literature. We also outline our own recent work as an example to illustrate how this stream of research can help improve marketing strategies and tactics on the Internet. Directions for future research are discussed in the last section.

scholarly journals Multipolar lasing modes from topological corner states

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ha-Reem Kim ◽  
Min-Soo Hwang ◽  
Daria Smirnova ◽  
Kwang-Yong Jeong ◽  
Yuri Kivshar ◽  
...  
Keyword(s):  
Domain Walls ◽  
Optical Gain ◽  
Topological Phases ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Finite Systems ◽  
Large Size ◽  
Topological States ◽  
Lasing Modes ◽  
Directional Transport

AbstractTopological photonics provides a fundamental framework for robust manipulation of light, including directional transport and localization with built-in immunity to disorder. Combined with an optical gain, active topological cavities hold special promise for a design of light-emitting devices. Most studies to date have focused on lasing at topological edges of finite systems or domain walls. Recently discovered higher-order topological phases enable strong high-quality confinement of light at the corners. Here, we demonstrate lasing action of corner states in nanophotonic topological structures. We identify several multipole corner modes with distinct emission profiles via hyperspectral imaging and discern signatures of non-Hermitian radiative coupling of leaky topological states. In addition, depending on the pump position in a large-size cavity, we generate selectively lasing from either edge or corner states within the topological bandgap. Our studies provide the direct observation of multipolar lasing and engineered collective resonances in active topological nanostructures.

Experimental resources needed to implement photon number splitting attack in quantum cryptography

2022 ◽  
Vol 19 (2) ◽  
pp. 025203
Author(s):  
S P Kulik ◽  
K S Kravtsov ◽  
S N Molotkov
Keyword(s):  
Coherent State ◽  
Quantum Key Distribution ◽  
Distribution Systems ◽  
Communication Channel ◽  
Random Phase ◽  
Photon Number ◽  
Fock States ◽  
Fock State ◽  
Experimental Parameters ◽  
Photon Number Splitting Attack

Abstract The analysis of the security of quantum key distribution systems with respect to an attack with nondemolishing measurement of the number of photons (photon number splitting—PNS attack) is carried out under the assumption that in the communication channel in each parcel there is a pure Fock state with a different number of photons, and the distribution of states by number of photons has Poisson statistics. In reality, in the communication channel in each parcel there are not individual Fock states, but a pure coherent state with a random phase—a superposition of Fock states with different numbers of photons. The paper analyzes the necessary experimental resources necessary to prepare individual Fock states with a certain number of photons from the superposition of Fock states for a PNS attack. Optical schemes for implementing such an attack are given, and estimates of experimental parameters at which a PNS attack is possible are made.

Sequential phonon measurements of atomic motion

2021 ◽  
Author(s):  
Atirach Ritboon ◽  
Lukáš Slodička ◽  
Radim Filip
Keyword(s):  
Cavity Qed ◽  
Quantum Fisher Information ◽  
Atomic Motion ◽  
Circuit Qed ◽  
Fock States ◽  
Fock State ◽  
Atomic Vibrations ◽  
State Generation ◽  
Available Information ◽  
Mechanical Sensing

Abstract The motion of trapped atoms plays an essential role in quantum mechanical sensing, simulations and computing. Small disturbances of atomic vibrations are still challenging to be sensitively detected. It requires a reliable coupling between individual phonons and internal electronic levels that light can readout. As available information in a few electronic levels about the phonons is limited, the coupling needs to be sequentially repeated to further harvest the remaining information. We analyze such phonon measurements on the simplest example of the force and heating sensing using motional Fock states. We prove that two sequential measurements are sufficient to reach sensitivity to force and heating for realistic Fock states and saturate the quantum Fisher information for a small amount of force or heating. It is achieved by the conventionally available Jaynes-Cummings coupling. The achieved sensitivities are found to be better than those obtained from classical states. Further enhancements are expectable when the higher Fock state generation is improved. The result opens additional applications of sequential phonon measurements of atomic motion. This measurement scheme can also be directly applied to other bosonic systems including cavity QED and circuit QED.

scholarly journals Hall viscosity, topological states and effective theories

2014 ◽  
Vol 28 (15) ◽  
pp. 1430007 ◽  
Author(s):  
Carlos Hoyos
Keyword(s):  
Transport Coefficient ◽  
Hall Conductivity ◽  
Topological Phases ◽  
Topological Order ◽  
Topological States ◽  
Effective Theories ◽  
Hall Viscosity ◽  
Galilean Invariant

Hall viscosity is a dissipationless transport coefficient whose value is quantized in units of the density in some topological phases and may be used as a measure of topological order. I give an overview of the Hall viscosity, its relation to Hall conductivity in Galilean invariant theories and its realization in effective theories.

scholarly journals Interacting edge states of fermionic symmetry-protected topological phases in two dimensions

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Joseph Sullivan ◽  
Meng Cheng
Keyword(s):  
Two Dimensions ◽  
Topological Phases ◽  
Edge States ◽  
Exactly Solvable ◽  
Fermionic Systems ◽  
Spatial Dimensions ◽  
Translation Symmetry ◽  
Interacting Systems ◽  
Symmetry Transformations ◽  
Symmetry Protected

Recently, it has been found that there exist symmetry-protected topological phases of fermions, which have no realizations in non-interacting fermionic systems or bosonic models. We study the edge states of such an intrinsically interacting fermionic SPT phase in two spatial dimensions, protected by \mathbb{Z}_4\times\mathbb{Z}_2^\mathsf{T}ℤ4×ℤ2𝖳 symmetry. We model the edge Hilbert space by replacing the internal \mathbb{Z}_4ℤ4 symmetry with a spatial translation symmetry, and design an exactly solvable Hamiltonian for the edge model. We show that at low-energy the edge can be described by a two-component Luttinger liquid, with nontrivial symmetry transformations that can only be realized in strongly interacting systems. We further demonstrate the symmetry-protected gaplessness under various perturbations, and the bulk-edge correspondence in the theory.

Coherent States and Fock States at Very High Average Photon Numbers

1981 ◽  
Vol 34 (4) ◽  
pp. 357
Author(s):  
GJ Troup ◽  
HS Perlman
Keyword(s):  
Coherent State ◽  
Field Intensity ◽  
Laser Field ◽  
Coherent States ◽  
Photon Number ◽  
Constant Field ◽  
Fock States ◽  
Fock State ◽  
Very High ◽  
Average Photon Number

A laser field may be idealized as a coherent state, but it is often more convenient to use Fock states fQr quantum electrodynamical calculations. A Fock state implies fluctuations in the field intensity, aptl a constant field intensity (coherent state) implies fluctuations in the photon number. Both these effects are discussed rigorously. When the average photon number tends to infinity, these different states become asymptotically indistinguishable.

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