1
$\begingroup$

This code worked in a previous version of ibmq_simulator and, I think, it works with qiskit_aer, but it doesn't work here and I don't understand the error message. The issue is there is no "path" from the input gates to the target basis, apparently. I don't know why - the input gates are only x with a condition.

Here's the code

import numpy as np
import matplotlib.pyplot as plt
import random
from qiskit import QuantumCircuit, QuantumRegister,  ClassicalRegister, execute
import qiskit
from qiskit_ibm_provider import IBMProvider

def create_registers():
    alice_q = QuantumRegister(1, 'alice (q)')
    peter_alice_q =         QuantumRegister(1, 'peter/alice (q)')
    peter_bob_q = QuantumRegister(1, 'peter/bob (q)')
    bob_c = ClassicalRegister(3, 'bob (c)')
    circ = QuantumCircuit(alice_q, peter_alice_q,
                          peter_bob_q, bob_c)
    return circ

circ = create_registers()
circ.x(2).c_if(1, 1) 
circ.measure(2, 2)

provider = IBMProvider()
device = provider.get_backend('ibmq_qasm_simulator')
shots = 1000
circ=qiskit.compiler.transpile(circ, basis_gates=['x', 'if_else'])
job = execute(circ, backend=device, shots=shots)

and here's the error message: raise TranspilerError( qiskit.transpiler.exceptions.TranspilerError: "Unable to translate the operations in the circuit: ['x', 'if_else', 'measure'] to the backend's (or manually specified) target basis: ['cu2', 'mcp', 'ry', 'rz', 'measure', 'rzz', 'ryy', 'tdg', 'mcz', 'mcswap', 'cz', 'rxx', 'cp', 'kraus', 'cx', 't', 'z', 'h', 'rx', 'u3', 'sdg', 'mcry', 'multiplexer', 'delay', 'u1', 'roerror', 'u', 'mcsx', 'mcy', 'diagonal', 'x', 'mcrz', 'ccx', 'mcrx', 'p', 'cswap', 'initialize', 'r', 'sx', 'mcr', 'mcu1', 'y', 'mcu3', 'rzx', 'csx', 's', 'id', 'mcx', 'barrier', 'swap', 'u2', 'cy', 'cu3', 'unitary', 'snapshot', 'mcu2', 'cu1']. This likely means the target basis is not universal or there are additional equivalence rules needed in the EquivalenceLibrary being used. For more details on this error see: https://qiskit.org/documentation/stubs/qiskit.transpiler.passes.BasisTranslator.html#translation_errors"

So either the target basis is not universal - and that seems unlikely - or there are equivalence rules needed. I don't know why an equivalence rule would be needed for such a simple circuit.

Furthermore, I see that the backed that works - aer - and the one that doesn't work, seem to use different equivalence libraries. How do I control which equivalence library I'm using?

$\endgroup$

1 Answer 1

0
$\begingroup$

The backend ibmq_qasm_simulator does not support dynamic circuits.

You can transpile your circuit as follows:

circ=qiskit.compiler.transpile(circ, backend=device, optimization_level=2)

note that, you should transpile the circuit with optimization_level greater than or equal to 2 to avoid the error you are facing. However, when you try to run the circuit:

job = device.run(circ, shots=shots)

you will get

UserWarning: The backend ibmq_qasm_simulator does not support dynamic circuits.
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.