Make fsim, rz, and w_1_2 gates work

[benjaminvillalonga]

Correctly implement reading and loading fsim, rz, and w_1_2 gates.

[benjaminvillalonga]

w_1_2 being hz_1_2

[alexandrupaler]

Is the line fsim(0.48112498558227507, 0.15642764309600338) equivalent to the cirq fsim gate where the floats are radians theta, phi and (from documentation of Cirq)

theta: Swap angle on the span(|01⟩, |10⟩) subspace, in radians.
                Determined by the strength and duration of the XX+YY
                interaction. Note: uses opposite sign convention to the
                iSWAP gate.
phi: Controlled phase angle, in radians. Determines how much the
                |11⟩ state is phased. Note: uses opposite sign convention to
                the CZPowGate.

[alexandrupaler]

Another two questions:

• for rz in the qflex circuits, is the parameter in radians?
• what is the hz_1_2 gate as Cirq gates?

If this and the above comment make sense, I could try and include fsim and rz

[benjaminvillalonga]

• fsim angles are given in units of pi, so the 0.48 above is almost pi/2 radians.
• I'm not familiar with Cirq, but hz_1_2 is the W_1_2 from supremacy circuits: sqrt(X+Y) / sqrt(2).

[alexandrupaler]

I see, this means W isops.PhasedXPowGate(phase_exponent=0.25, exponent=0.5) where

phase_exponent: The exponent on the Z gates conjugating the X gate.
exponent: The exponent on the X gate conjugated by Zs.

Please correct me if I am wrong.

[benjaminvillalonga]

See #155 for continued discussion. Implementation will happen there.

[benjaminvillalonga]

This PR was solved in #155