Global Alliance in Management Education

About: Global Alliance in Management Education is a based out in . It is known for research contribution in the topics: Magnetic field & Skyrmion. The organization has 577 authors who have published 2057 publications receiving 72848 citations. The organization is also known as: CEMS & The Global Alliance in Management Education.

Learning robust pulses for generating universal quantum gates.

Abstract: Constructing a set of universal quantum gates is a fundamental task for quantum computation. The existence of noises, disturbances and fluctuations is unavoidable during the process of implementing quantum gates for most practical quantum systems. This paper employs a sampling-based learning method to find robust control pulses for generating a set of universal quantum gates. Numerical results show that the learned robust control fields are insensitive to disturbances, uncertainties and fluctuations during the process of realizing universal quantum gates.

Boltzmann sampling from the Ising model using quantum heating of coupled nonlinear oscillators.

Abstract: A network of Kerr-nonlinear parametric oscillators without dissipation has recently been proposed for solving combinatorial optimization problems via quantum adiabatic evolution through its bifurcation point. Here we investigate the behavior of the quantum bifurcation machine (QbM) in the presence of dissipation. Our numerical study suggests that the output probability distribution of the dissipative QbM is Boltzmann-like, where the energy in the Boltzmann distribution corresponds to the cost function of the optimization problem. We explain the Boltzmann distribution by generalizing the concept of quantum heating in a single nonlinear oscillator to the case of multiple coupled nonlinear oscillators. The present result also suggests that such driven dissipative nonlinear oscillator networks can be applied to Boltzmann sampling, which is used, e.g., for Boltzmann machine learning in the field of artificial intelligence.

Cavity QED in the Ultrastrong Coupling Regime: Photon Bunching from the Emission of Individual Dressed Qubits

Abstract: Photon antibunching in the light scattered by single quantum emitters is one of the hallmarks of quantum optics, providing an unequivocal demonstration of the quantized nature of the electromagnetic field. Antibunching can be intuitively understood by the need for a two-level system lying in its lower state after emitting a photon to be re-excited into the upper one before a second emission can take place. Here we show that such a picture breaks down in the ultrastrong light–matter coupling regime, when the coupling strength becomes comparable to the bare emitter frequency. Specializing to the cases of both a natural and an artificial atom, we thus show that a single emitter coupled to a photonic resonator can emit bunched light. The result presented herein is clear evidence of how the ultrastrong coupling regime is able to change the nature of individual atoms.

Dynamical sign reversal of magnetic correlations in dissipative Hubbard models

Abstract: In quantum magnetism, the virtual exchange of particles mediates an interaction between spins. Here, we show that an inelastic Hubbard interaction fundamentally alters the magnetism of the Hubbard model due to dissipation in spin-exchange processes, leading to sign reversal of magnetic correlations in dissipative quantum dynamics. This mechanism is applicable to both fermionic and bosonic Mott insulators, and can naturally be realized with ultracold atoms undergoing two-body inelastic collisions. The dynamical reversal of magnetic correlations can be detected by using a double-well optical lattice or quantum-gas microscopy, the latter of which facilitates the detection of the magnetic correlations in one-dimensional systems because of spin-charge separation. Our results open a new avenue toward controlling quantum magnetism by dissipation.

Phononic Weyl points and one-way topologically protected nontrivial phononic surface arc states in noncentrosymmetric WC-type materials

Abstract: By means of first-principles calculations, we have predicted the existence of phononic Weyl points (WPs) along the high-symmetric K($\frac{1}{3},\frac{1}{3},0$)-H($\frac{1}{3},\frac{1}{3},\frac{1}{2}$) line in the Brillouin zone for a series of noncentrosymmetric hexagonal WC-type materials (HfS, HfSe, IrB, MoC, MoN, MoP, NbN, NbS, TaN, TaS, TiO, TiS, WN, ZrS, ZrSe, and ZrTe) and these WPs carry nonzero topological charges. In terms of symmetry analysis, we have further derived two-band $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ models to describe these WPs. For most WPs a first-order theory is sufficient to reproduce well the phonon spectra around these WPs. However, for some WPs a second-order theory has to be required. Particularly, when the second-order term plays a leading role, a topological charge $\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.16em}{0ex}}\mathrm{WP}$ on the K-H line is accompanied by three nearby WPs with the opposite charges ($\ensuremath{\mp}1$) off the K-H line. These four spatially close (in the reciprocal space) WPs have a total topological charge of $\ensuremath{\mp}2$. On the crystal ($10\overline{1}0$) and ($01\overline{1}0$) surfaces, we have observed clear one-way topologically protected nontrivial phononic surface arc states connecting two WPs with opposite chirality. Our results pave the way for future experimental studies of the topological phonons for those WC-type materials.