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We analyze the spectrum of a discrete Schrödinger operator with a potential given by a periodic variant of the Anderson model. In order to do so, we study the uniform hyperbolicity of a Schrödinger cocycle generated by the SL(2,R) transfer matrices. In the specific case of the potential generated by an alternating sequence of random values, we show that the almost sure spectrum consists of at most 4 intervals.
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On the number of closed gaps of discrete periodic one-dimensional operators
From the general inverse theory of periodic Jacobi matrices, it is known that a periodic Jacobi matrix of minimal period p≥2 may have at most p−2 closed spectral gaps. We discuss the maximal number of closed gaps for one-dimensional periodic discrete Schrödinger operators of period p. We prove nontrivial upper and lower bounds on this quantity for large p and compute it exactly for p≤6. Among our results, we show that a discrete Schrödinger operator of period four or five may have at most a single closed gap, and we characterize exactly which potentials may exhibit a closed gap. For period six, we show that at most two gaps may close. In all cases in which the maximal number of closed gaps is computed, it is seen to be strictly smaller than p−2, the bound guaranteed by the inverse theory. We also discuss similar results for purely off-diagonal Jacobi matrices.
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- Award ID(s):
- 2213196
- PAR ID:
- 10601318
- Publisher / Repository:
- AIP Publishing
- Date Published:
- Journal Name:
- Journal of Mathematical Physics
- Volume:
- 65
- Issue:
- 5
- ISSN:
- 0022-2488
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0175428
