Measuring the Parity of an N -Qubit State
Bei Zeng, Dong Zhou, Lixing You · Physical Review Letters · 2005
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.