1 / 1

Localization and antiresonance in disordered qubit chains

localized excitation. e 1 +( g 2 +J 2 ) 1/2. one magnon. e 1. 2J. doublet. 2 e 1 +g+J D. J/ D. BP. 2 e 1 +J D. n 0 n 0 +1. 2J. 2 e 1 +g. LDP. n 0 +1 n 0 +2. 2e 1. 4J. n 0 n. …. Localization and antiresonance in disordered qubit chains.

violet-mcintosh
Download Presentation

Localization and antiresonance in disordered qubit chains

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. localized excitation e1 +(g2+J2)1/2 one magnon e1 2J doublet 2e1+g+JD J/D BP 2e1+JD n0 n0+1 2J 2e1+g LDP n0 +1n0+2 2e1 4J n0 n … Localization and antiresonance in disordered qubit chains PRB 68, 214410 (03) JPA 36, L561 (03) L. F. Santos and M. I. Dykman Michigan State University • Quantum computer modeled with an anisotropic spin-1/2 chain • A defect in the chain a multiple localized many-excitation states • Many particle antiresonance    THE MODEL QCs with perpetually coupled qubits: Nuclear spins with dipolar coupling Josephson junction systems Electrons on helium ONE EXCITATION THE HAMILTONIAN ELECTRONS HELIUM Energy: CONFINING ELECTRODES Qubit energy difference can becontrolled Localized state on the defect: no threshold in an infinite chain. Localization length: g e0 e0 e0 e0 n0 n0+1 n0+2 n0-1 Stronganisotropy:D>>1 study many-body effects in a disordered spin system    NON-RESONANT DEFECT : g < JD RESONANT DEFECT: g ~ JD TWO EXCITATIONS:IDEAL CHAIN ONE DEFECT AT n0 The bound pair NEXT to the defect becomes strongly hybridized with the LDPs Strong anisotropy D>>1 Localized BOUND PAIRS: one excitation on the defect next to the defect (surface-type) doublet 2e1+g+JD Narrow band of bound pairs bound pairs localized BP J/D 2e1+JD J/D 2e1+JD n0 +1n0+2 LDP + 2J 2e1+g n0 n0+2 two magnons Localized - delocalized pairs Unbound magnons Localization length: 4J 2e1 2e1 4J when JD –g = J/2    TIME EVOLUTION (numerical results - 10 sites) SCATTERING PROBLEM FOR ANTIRESONANCE ANTIRESONANT DECOUPLINGg ~ JD Resonanting bound pairs and states with one excitation on the defectDO NOT mix g=JD/4 g=JD nonoverlapping bands, a pairNEXT to the defect mixes with bound pairs only overlapping bands: a pairNEXT to the defect mixes with localized-delocalized pairsonly The coefficient of reflection of the propagating magnon from the defect R=1 bound pair NEXTto the defect Initial state: (n0 +1, n0 +2) … bound pair + n0 localized delocalized pair Final state: (n0 +2, n0 +3) + (n0 , n0 +3) n0

More Related