Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement

Details Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement

2007-01-04

arxiv.org/abs/cond-mat/0701078v2

Phys. Rev. A 76, 012325 (2007)

Physics

Condensed Matter

Mesoscale and Nanoscale Physics

12 pages, 6 figures

Scientific paper

10.1103/PhysRevA.76.012325

We study how the spontaneous relaxation of a qubit affects a continuous quantum non-demolition measurement of the initial state of the qubit. Given some noisy measurement record $\Psi$, we seek an estimate of whether the qubit was initially in the ground or excited state. We investigate four different measurement protocols, three of which use a linear filter (with different weighting factors) and a fourth which uses a full non-linear filter that gives the theoretically optimal estimate of the initial state of the qubit. We find that relaxation of the qubit at rate $1/T_1$ strongly influences the fidelity of any measurement protocol. To avoid errors due to this decay, the measurement must be completed in a time that decrease linearly with the desired fidelity while maintaining an adequate signal to noise ratio. We find that for the non-linear filter the predicted fidelity, as expected, is always better than the linear filters and that the fidelity is a monotone increasing function of the measurement time. For example, to achieve a fidelity of 90%, the box car linear filter requires a signal to noise ratio of $\sim 30$ in a time $T_1$ whereas the non-linear filter only requires a signal to noise ratio of $\sim 18$.

Affiliated with

Also associated with

No associations

Rating

Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protocols for optimal readout of qubits using a continuous quantum nondemolition measurement will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-309949