Simple PhaseE

 IBM Learn Lesson 7

The circuit below allows one to take phase into account, thanks to phase kickback.

                                                               

In effect, qubit(1) needs to be on for phase to show up at all. The model is

more general, with a circuit with any number of qubits producing phase movement.

                                                                          

At theta =.7, we are at 252 degrees. (divide by2; theta is on pi. Thus we have 126°).

Making sure we have degrees on the left!

sin^2(126°) = 0.345491...

cos^2(126°) = 0.654508...

                                                                       *     *     *

PHASE KICKBACK: In a classical context, an if... then clause means that the target

changes to match the control. With respect to phase, a change in the phase alters the 

control.

                                                                              

*     *     *

ON THE UNIT CIRCLE: Because the hypothenuse is always 1, sin^2(x) + cos^2(y)

are equal to 1^2. 

                                                                               

Interactive Unit Circle (mathsisfun.com)