1,396 research outputs found
Quantum Zeno effect with a superconducting qubit
Detailed schemes are investigated for experimental verification of Quantum
Zeno effect with a superconducting qubit. A superconducting qubit is affected
by a dephasing noise whose spectrum is 1/f, and so the decay process of a
superconducting qubit shows a naturally non-exponential behavior due to an
infinite correlation time of 1/f noise. Since projective measurements can
easily influence the decay dynamics having such non-exponential feature, a
superconducting qubit is a promising system to observe Quantum Zeno effect. We
have studied how a sequence of projective measurements can change the dephasing
process and also we have suggested experimental ways to observe Quantum Zeno
effect with a superconducting qubit. It would be possible to demonstrate our
prediction in the current technology
Influence of deflocculant on the isoelectric point of refractory powders: Considerations on the action of deflocculant
Isoelectric point changes in suspensions of refractory materials vis-a-vis the role of deflocculants used in monolithic refractories were investigated by considering the mineral compositions and adsorbed ions in four kinds of clay. Three types of curves represented the relation between the isoelectric point and the deflocculant. The surface charge of clay particles in the suspensions became negative as a result of the deflocculant, since the isoelectric point of suspensions decreased as the deflocculant was added. The isoelectric point changes of calcined alumina were also compared with those of the clays, and a similar phenomenon was observed, except that the deflocculant dispersed the calcined alumina better than it did the clays. A simple model was used to analyze the results
Dephasing of a superconducting flux qubit
In order to gain a better understanding of the origin of decoherence in
superconducting flux qubits, we have measured the magnetic field dependence of
the characteristic energy relaxation time () and echo phase relaxation
time () near the optimal operating point of a flux qubit. We
have measured by means of the phase cycling method. At the
optimal point, we found the relation . This means
that the echo decay time is {\it limited by the energy relaxation} (
process). Moving away from the optimal point, we observe a {\it linear}
increase of the phase relaxation rate () with the applied
external magnetic flux. This behavior can be well explained by the influence of
magnetic flux noise with a spectrum on the qubit
Dephasing of a superconducting flux qubit
In order to gain a better understanding of the origin of decoherence in
superconducting flux qubits, we have measured the magnetic field dependence of
the characteristic energy relaxation time () and echo phase relaxation
time () near the optimal operating point of a flux qubit. We
have measured by means of the phase cycling method. At the
optimal point, we found the relation . This means
that the echo decay time is {\it limited by the energy relaxation} (
process). Moving away from the optimal point, we observe a {\it linear}
increase of the phase relaxation rate () with the applied
external magnetic flux. This behavior can be well explained by the influence of
magnetic flux noise with a spectrum on the qubit
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