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Feedback Control of a Solid-State Qubit Using High-Fidelity Projective Measurement

Mon, 2013-02-11 18:25 - Daniel Rudolph
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Date: 
2012-12-10
Author(s): 

D. Ristè, C. C. Bultink, K. W. Lehnert, and L. DiCarlo

Reference: 

Phys. Rev. Lett. 109, 240502 (2012)

URL: 

http://link.aps.org/doi/10.1103/PhysRevLett.109.240502

We demonstrate feedback control of a superconducting transmon qubit using discrete, projective measurement and conditional coherent driving. Feedback realizes a fast and deterministic qubit reset to a target state with 2.4% error averaged over input superposition states, and allows concatenating experiments more than 10 times faster than by passive initialization. This closed-loop qubit control is necessary for measurement-based protocols such as quantum error correction and teleportation.