Stochastic-master-equation analysis of optimized three-qubit nondemolition parity measurements
Journal article, 2014

We analyzea direct parity measurement of the state of three superconducting qubits in circuit quantum electrodynamics. The parity is inferred from a homodyne measurement of the reflected and transmitted microwave radiation, and the measurement is direct in the sense that the parity is measured without the need for any quantum circuit operations or for ancilla qubits. Qubits are coupled to two resonant-cavity modes, allowing the steady state of the emitted radiation to satisfy the necessary conditions to act as a pointer state for the parity. However, the transient dynamics violates these conditions, and we analyze this detrimental effect and show that it can be overcome in the limit of a weak measurement signal. Our analysis shows that, with a moderate degree of postselection, it is possible to achieve postmeasurement states with fidelity of order 95%. We believe that this type of measurement could serve as a benchmark for future error correction protocols in a scalable architecture.

Author

Lars Tornberg

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

S. Barzanjeh

D. P. DiVincenzo

Physical Review A - Atomic, Molecular, and Optical Physics

1050-2947 (ISSN) 1094-1622 (eISSN)

Vol. 89 3 11-

Subject Categories

Physical Sciences

DOI

10.1103/PhysRevA.89.032314

More information

Created

10/6/2017