Basic circuit serialization for tequila

• prototype status
• works with json
• can be used with orquestra

Encode Circuits

Here is one explicit example

# not in tequila namespace yet
from genencoder import CircuitGenEncoder
import tequila as tq

my_tequila_circuit =  tq.gates.H(0)
my_tequila_circuit += tq.gates.X(target=4,control=2)
my_tequila_circuit += tq.gates.Rx(angle="a", target=0) 
my_tequila_circuit += tq.gates.Rx(angle="b", target=2, control=1)

encoder = CircuitGenEncoder()

# encode circuit
circuit_string1 = encoder(my_tequila_circuit)

# encode circuit with explicit variables
# this will determine only variable a, variable b stays a variable after decoding
circuit_string2 = encoder(my_tequila_circuit, variables={"a":2.0})

# deconde circuit
the_same_tequila_circuit = encoder(circuit_string1)

Currently everything is encoded generator-based. For gates like H and controls this might seem odd on first sight.
The CRx gate is for example encoded as: exp(-i b/2 * G) with generator G = NOT(1) * X(2) = 0.5(1-Z)(1) * X(2),
and the Hadamard gate as H = Ry(pi/4)Rz(pi)Ry(-pi/4).

The encoded circuit strings are:

circuit_string1 = @11.7810Y(0)|@3.1416Z(0)|@0.7854Y(0)|@0.5000X(4)|@12.0664Z(2)X(4)|@0.5000Z(2)|[email protected](0)|[email protected](2)|[email protected](1)X(2)| 
circuit_string2 = @11.7810Y(0)|@3.1416Z(0)|@0.7854Y(0)|@0.5000X(4)|@12.0664Z(2)X(4)|@0.5000Z(2)|@2.0000X(0)|[email protected](2)|[email protected](1)X(2)|

Separators @ and | can be can be changed on initialization

encoder = CircuitGenEncoder(angle_separator="@", gate_separator="|")

Create Random circuits

from genencoder import CircuitGenerator

#Some comments:
#connectivity = "local_line" # can be "local_ring" as well, or dictionary defining custom connectiviy: Example 4 qubits all connected to qubit 0 would be connectivity={0:[1,2,3], 1:[0], 2:[0], 3:[0]} (redundancies are not automatically corrected right now)
#fix_angles={"XY":numpy.pi/2} # will fix the angle of all gates with this generator to this value

generator = CircuitGenerator(depth=10, connectivity="local_line", n_qubits=4, generators=["Y", "XY"], fix_angles={"XY":numpy.pi/2})

my_random_circuit = generator()