Optimal feedback control for the rapid preparation of a single qubit

Abstract

We consider the use of feedback control during a measurement to increase the rate at which a single qubit is purified, and more generally the rate at which near-pure states may be prepared. We derive the optimal bang-bang algorithm for rapid state preparation from an initially completely mixed state when the measurement basis is unrestricted, and evaluate its performance numerically. We also consider briefly the case in which the measurement basis is fixed with respect to the state to be prepared, and describe the qualitative structure of the optimal bang-bang algorithm.

8 pages, revtex4-1, 3 pdf figures. v2: corrects an error in Eqs (12) and (13)

Cited by in corpus (12)

• Quantum control theory and applications: A survey
• Rapid State-Reduction of Quantum Systems Using Feedback Control
• Qubit feedback and control with kicked quantum nondemolition measurements: A quantum Bayesian analysis
• Reconsidering Rapid Qubit Purification by Feedback
• Quantum feedback for rapid state preparation in the presence of control imperfections
• Rapid state purification protocols for a Cooper pair box
• Weak measurement and rapid state reduction in bipartite quantum systems
• Method for quantum-jump continuous-time quantum error correction
• Maximum information gain in weak or continuous measurements of qudits: complementarity is not enough
• Optimality of qubit purification protocols in the presence of imperfections
• Hitting statistics from quantum jumps
• Paradigms for Quantum Feedback Control