title: Measuring the parity of an N-qubit state.
abstract: We present a scheme for a projective measurement of the parity operator Pz = Product(N)i=1 sigma(i)z of N qubits. Our protocol uses a single ancillary qubit, or a probe qubit, and involves manipulations of the total spin of the N qubits without requiring individual addressing. We illustrate our protocol in terms of an experimental implementation with atomic ions in a two-zone linear Paul trap, and further discuss its extensions to several more general cases.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: B
authors.initials: B
authors.lastname: Zeng
authors.forename: D L
authors.initials: DL
authors.lastname: Zhou
authors.forename: L
authors.initials: L
authors.lastname: You