Vol. 224, No. 1, 2006

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On the nullcone of representations of reductive groups

Hanspeter Kraft and Nolan R. Wallach

Vol. 224 (2006), No. 1, 119–139
Abstract

We study the geometry of the nullcone N = NV k for several copies of a representation V of a reductive group G and its behavior for different k. We show that for large k there is a certain “stability” with respect to the irreducible components. In the case of the so-called 𝜃-representations, this can be made more precise by using the combinatorics of the weight system as a subset of the root system. All this finally allows us to calculate explicitly and in detail a number of important examples, such as the cases of 3- and 4-qubits, which play a fundamental rôle in quantum computing.

Keywords
nullcone, invariant, qubit, 𝜃-representation
Mathematical Subject Classification 2000
Primary: 20G20, 20G05, 14L24
Milestones
Received: 21 February 2005
Accepted: 25 September 2005
Published: 1 March 2006
Authors
Hanspeter Kraft
Mathematisches Institut der Universität Basel
Rheinsprung 21
CH-4051 Basel
Switzerland
Nolan R. Wallach
Department of Mathematics
University of California, San Diego
9500 Gilman Drive
La Jolla, CA 92093-0112
United States