Symmetries and invariants for non-Hermitian Hamiltonians

Autor: Miguel Ángel Simón, Álvaro Buendía, J. G. Muga
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Mathematics, Vol 6, Iss 7, p 111 (2018)
Druh dokumentu: article
ISSN: 2227-7390
DOI: 10.3390/math6070111
Popis: We discuss Hamiltonian symmetries and invariants for quantum systems driven by non-Hermitian Hamiltonians. For time-independent Hermitian Hamiltonians, a unitary or antiunitary transformation AHA† that leaves the Hamiltonian H unchanged represents a symmetry of the Hamiltonian, which implies the commutativity [H,A]=0 and, if A is linear and time-independent, a conservation law, namely the invariance of expectation values of A. For non-Hermitian Hamiltonians, H† comes into play as a distinct operator that complements H in generalized unitarity relations. The above description of symmetries has to be extended to include also A-pseudohermiticity relations of the form AH=H†A. A superoperator formulation of Hamiltonian symmetries is provided and exemplified for Hamiltonians of a particle moving in one-dimension considering the set of A operators that form Klein’s 4-group: parity, time-reversal, parity&time-reversal, and unity. The link between symmetry and conservation laws is discussed and shown to be richer and subtler for non-Hermitian than for Hermitian Hamiltonians.
Databáze: Directory of Open Access Journals
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