The simple tunability of the current-biased Josephson junction in its zero voltage state is one of the key advantages the phase qubit has over some other qubit implementations, although it also limits the performance of this device, as fluctuations in current generate fluctuations in the plasma frequency, which causes dephasing of the quantum states.
42.
Is the plasma frequency, e is the magnitude of the electron charge, m is the electron mass, T _ e is the electron temperature ( Boltzmann's constant equal to one ), and \ gamma \ left ( \ omega \ right ) is a factor that varies with frequency from one to three.
43.
This formula is valid away from strong atomic or molecular resonances ( where \ epsilon would have a large imaginary part ) and at frequencies which are much below both the material's plasma frequency ( dependent on the density of free electrons in the material ) and the reciprocal of the mean time between collisions involving the conduction electrons.
44.
Where \ omega _ p \ equiv ( n _ ee ^ 2 / \ epsilon _ 0m _ e ) ^ { 1 / 2 } is the electron plasma frequency, \ omega is the photon frequency, n _ e, n _ i is the number density of electrons and ions, and other symbols are physical constants.
45.
Most military airborne and air defense radars, however, operate in VHF, UHF, and microwave band, which have frequencies higher than the characteristic plasma frequency of ionosphere, therefore microwave can penetrate the ionosphere and communication between the ground and communication satellites demonstrates is possible . ( " Some " frequencies can penetrate the ionosphere ).
46.
The Delft read-out scheme is based on a SQUID loop that is inductively coupled to the qubit, the qubit's state influences the critical current of the SQUID . The critical current can then be read-out using ramped measurement currents through the SQUID . Recently the group has used the plasma frequency of the SQUID as the read-out variable.
47.
The use of plasmas to control the reflected electromagnetic radiation from an object ( Plasma stealth ) is feasible at suitable frequency where the conductivity of the plasma allows it to interact strongly with the incoming radio wave, and the wave can either be absorbed and converted into thermal energy, or reflected, or transmitted depending on the relationship between the radio wave frequency and the characteristic plasma frequency.
48.
On length scales shorter than the ion inertial length c / \ omega _ { pi } ( where \ omega _ { pi } \ equiv \ sqrt { \ frac { n _ iZ ^ 2e ^ 2 } { \ epsilon _ 0m _ i } } is the ion plasma frequency ), ions decouple from electrons and the magnetic field becomes frozen into the electron fluid rather than the bulk plasma.
