Quantum Theory, Groups and Representations

Masahito Hayashi

正人 林

N. V. Borisov

Kieran Mastel

The n-qubit Pauli group and its normalizer, the n-qubit Clifford group, have applications in quantum error correction and device characterization. Recent applications have used the representation theory of the Clifford group. We apply the tools of (the coincidentally named) Clifford theory to examine the representation theory of the Clifford group using the much simpler representation theory of the Pauli group. We find an unexpected correspondence between irreducible characters of the n-qubit Clifford group and those of the (n+1)-qubit Clifford group.

Casey Blood

The current form of quantum mechanics is very successful and is almost certainly correct. It is remarkable, however, that the entire structure-from the mass, spin and charge labels on particlelike states to antisymmetry to broken internal symmetries to gauge transformations to the equations of motion-is built upon concepts from group representation theory. That is, the theory is constructed exactly as if it were a representational form of an underlying theory. Our proposed form for the underlying theory is that it is based on a linear equation, OF(V)=0. F is a function of some set of independent, currently unknown variables V, with O being a linear, partial differential operator in those variables. The operator is assumed to be invariant under a group of transformations of the Vs, homomorphic to the direct product of the inhomogeneous Lorentz group and the internal symmetry group. In such a theory, a state vector, denoted by a ket with group-theoretic labels, would represent a function of the independent variables. In addition to explaining the group representational structure of quantum mechanics, an underlying theory offers insight into gauge theory.