StateVector in Qibo

[geexie]

does Qibo support some analogy for qiskit StateVector. It's handy to simulate circuits for debugging purpose. Like this in case of Qibo I have to add initialisation, measurement and run the circuit.

for i in ["".join(seq) for seq in itertools.product("01", repeat=4)]:
    # Qiskit
    cu = QuantumCircuit(4)

    # Qibo
    init = Circuit(4)
    for j, c in filter(lambda x: int(x[1]) == 1, enumerate(i)):
        init.add(gates.X(j))

    init = init + xymod4

    cu.ccx(1, 3, 2)
    cu.cx(1, 3)
    cu.cx(0, 2)
    # print (cu)

    sv = Statevector.from_label(i[::-1])
    sv1 = sv.evolve(cu)
    # sv = partial_trace(sv, [2,3])

    # r = list(sv.data.real).index(1.)
    print(i, sv1.data.real,
        #   0 if qubit_state(sv1, [1, 2, 3])[0].real == 1 else 1,
        #   0 if qubit_state(sv1, [0, 2, 3])[0].real == 1 else 1,
          str(0 if qubit_state(sv1, [0, 1, 3])[0].real == 1 else 1)+
          str(0 if qubit_state(sv1, [0, 1, 2])[0].real == 1 else 1))#, "result", r, "expected")

    init.add(gates.M(*range(2,4)))
    # print (init)
    result = init(nshots=4096)
    print(i, result, list(result.frequencies(binary=True).keys())[0])

[renatomello]

@geexie It is hard from this snippet alone to understand exactly what you want to do. Could you go a bit more into detail? Also, this snippet is incomplete. For instance, xymod4 and qubit_state are not defined.

[geexie]

sorry for a messy example. I'm basically trying to run circuit without prologue with initialisation and measurement epilogue. I qiskit I can do for example loading from qasm and then evolve on a specific state vector

circuit = QuantumCircuit.from_qasm_file("4mod5.qasm")
for i in ["".join(seq) for seq in itertools.product("01", repeat=3)]:
    sv = Statevector.from_label(i)
    sv = sv.evolve(circuit)
    # analyse results

in Qibo I need to construct full curcuit

with open('4mod5.qasm', 'r') as file:
    content = file.read()
    c = Circuit.from_qasm(content)
    for i in ["".join(seq) for seq in itertools.product("01", repeat=3)]:
        init = Circuit(3)
        for j, c in filter(lambda x: int(x[1]) == 1, enumerate(i)):
            init.add(gates.X(j))
        init  = init + c
        init.add(gates.M(*range(0,3)))
        result = init(nshots=4096)
        # analyse results

[renatomello]

from qibo.models.encodings import comp_basis_encoder


nqubits = 3
with open('4mod5.qasm', 'r') as file:
    content = file.read()
    qasm_circuit = Circuit.from_qasm(content)
    for string in ["".join(seq) for seq in itertools.product("01", repeat=nqubits)]:
        init = comp_basis_encoder(string)
        init  += qasm_circuit  # this step works if both circuits have the same number of qubits
        init.add(gates.M(*range(nqubits)))
        result = init(nshots=4096)
        # analyse results

When it comes to measurements, adding them or not is a choice. I do not think there is a more concise way than the one you are already doing. If you want the exact statevector, you could just simulate the circuit without adding measurements.

[alecandido]

I wonder whether you want

1. to use the state vector as initial state (which is available in Qibo), or
2. to get it as a result (which is the default result), or
3. just a constructor to create some specific state out of a bit string, or some other information (which can do, but you just need to directly manipulate arrays with NumPy or another array framework, not going through Qibo - but we could introduce convenient constructors, if relevant), or
4. something else

Is it one of the first three?

[geexie]

The 1st ad the 2d I guess, probably I just didn't find it in examples... please see my comment above for a (hopefully) better code snippet

[renatomello]

For 3 there is `qibo.models.encodings.comp_basis_encoder`.

…

On Tue, 22 Jul 2025 at 11:53, Alessandro Candido ***@***.***> wrote: I wonder whether you want 1. to use the state vector as initial state (which is available in Qibo), or 2. to get it as a result (which is the default result), or 3. just a constructor to create some specific state out of a bit string, or some other information (which can do, but you just need to directly manipulate arrays with NumPy or another array framework, not going through Qibo - but we could introduce convenient constructors, if relevant), or 4. something else Is it one of the first three? — Reply to this email directly, view it on GitHub <#1695 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABH5QVRQSQMHVN2SINGFV5D3JXUYLAVCNFSM6AAAAACCBLYGWSVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGOBUGM2TQNQ> . You are receiving this because you commented.Message ID: ***@***.***>