Heisenberg-Weyl Observables: Bloch vectors in phase space

Understand

We introduce a Hermitian generalization of Pauli matrices to higher dimensions which is based on Heisenberg-Weyl operators.

• The complete set of Heisenberg-Weyl observables allows us to identify a real-valued Bloch vector for an arbitrary density operator in discrete phase space, with a smooth transition to infinite dimensions.
• Furthermore, we derive bounds on the sum of expectation values of any set of anti-commuting observables.
• Such bounds can be used in entanglement detection and we show that Heisenberg-Weyl observables provide a first non-trivial example beyond the dichotomic case.