Transfer radio-frequency energy

The detector system is used to note that energy is being transferred from the radiofrequency beam to the nucleus radio frequency. 

The RWA in Eq. (4.183) breaks down if the transfer time is similar to or less than the inverse energy separation of the qubit, t < This is a common case for qubits whose resonance frequency is in the microwave (GHz) or radio frequency (RE MHz) range. In such cases, the optimization process must take into account both the dephasing due to the bath as in Eqs. (4.189)-(4.191) and the error due to the non-RWA terms when minimizing the infidelity. 

In the probe area, where the sample is placed, resonance is obtained by superimposing a weak oscillating field B on the field B0 generated by a coil that is fed by an AC radiofrequency. In order for B to have the proper space orientation, the propagation axis of the radiofrequency has to be perpendicular to the Oz axis (Fig. 9.8). The transfer of energy from the source to the nuclei occurs when the radio-frequency of the source and the frequency of precession are the same. When this occurs, nuclei in energy state E can pass to energy state E2 the relative populations become modified. 

The cross-sectional view of an inductively coupled plasma burner in Figure 21-12 shows two turns of a 27- or 41-MHz induction coil wrapped around the upper opening of the quartz apparatus. High-purity Ar gas is fed through the plasma gas inlet. After a spark from a Tesla coil ionizes Ar, free electrons are accelerated by the radio-frequency field. Electrons collide with atoms and transfer their energy to the entire gas. maintaining a temperature of 6 000 to 10 000 K. The quartz torch is protected from overheating by Ar coolant gas. 

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