scholarly journals Observation of Dirac monopoles in a synthetic magnetic field

Nature ◽  
2014 ◽  
Vol 505 (7485) ◽  
pp. 657-660 ◽  
Author(s):  
M. W. Ray ◽  
E. Ruokokoski ◽  
S. Kandel ◽  
M. Möttönen ◽  
D. S. Hall
2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Omar Jamadi ◽  
Elena Rozas ◽  
Grazia Salerno ◽  
Marijana Milićević ◽  
Tomoki Ozawa ◽  
...  

Abstract We report the realization of a synthetic magnetic field for photons and polaritons in a honeycomb lattice of coupled semiconductor micropillars. A strong synthetic field is induced in both the s and p orbital bands by engineering a uniaxial hopping gradient in the lattice, giving rise to the formation of Landau levels at the Dirac points. We provide direct evidence of the sublattice symmetry breaking of the lowest-order Landau level wavefunction, a distinctive feature of synthetic magnetic fields. Our realization implements helical edge states in the gap between n = 0 and n = ±1 Landau levels, experimentally demonstrating a novel way of engineering propagating edge states in photonic lattices. In light of recent advances in the enhancement of polariton–polariton nonlinearities, the Landau levels reported here are promising for the study of the interplay between pseudomagnetism and interactions in a photonic system.


2008 ◽  
Vol 26 (11) ◽  
pp. 3491-3499 ◽  
Author(s):  
M. Hamrin ◽  
K. Rönnmark ◽  
N. Börlin ◽  
J. Vedin ◽  
A. Vaivads

Abstract. We present a method, GALS (Gradient Analysis by Least Squares) for estimating the gradient of a physical field from multi-spacecraft observations. To obtain the best possible spatial resolution, the gradient is estimated in the frame of reference where structures in the field are essentially locally stationary. The estimates are refined iteratively by a least squares method. We show that GALS is not very sensitive to the spacecraft configuration and resolves structures much smaller than the characteristic size of the spacecraft distribution. Furthermore, GALS requires little user input. GALS has been tested on synthetic magnetic field data and data from the Cluster FGM instrument. GALS will also be useful for other types of data. The results indicate that GALS is robust and superior to the curlometer method for estimating the current from magnetic field measurements.


2019 ◽  
Vol 100 (22) ◽  
Author(s):  
Elvia Colella ◽  
Farokh Mivehvar ◽  
Francesco Piazza ◽  
Helmut Ritsch

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