NoureldinYosri
commented
4 months ago hi, this is exactly as the error says. the qubits don't exist on the device. the realsitic noise model represent the noise for the device, that's noise is keyed by qubits and qubit pairs. you can list the qubits on the device by calling
>> noise_props.qubits
[cirq.GridQubit(3, 2),
cirq.GridQubit(4, 1),
cirq.GridQubit(4, 2),
cirq.GridQubit(4, 3),
cirq.GridQubit(5, 0),
cirq.GridQubit(5, 1),
cirq.GridQubit(5, 2),
cirq.GridQubit(5, 3),
cirq.GridQubit(5, 4),
cirq.GridQubit(6, 1),
cirq.GridQubit(6, 2),
cirq.GridQubit(6, 3),
cirq.GridQubit(6, 4),
cirq.GridQubit(6, 5),
cirq.GridQubit(7, 2),
cirq.GridQubit(7, 3),
cirq.GridQubit(7, 4),
cirq.GridQubit(7, 5),
cirq.GridQubit(7, 6),
cirq.GridQubit(8, 3),
cirq.GridQubit(8, 4),
cirq.GridQubit(8, 5),
cirq.GridQubit(9, 4)]for example I reran you circuit using cirq.GridQubit(4, 1), cirq.GridQubit(4, 2) which exist on the device
>> q0, q1 = cirq.q(4, 1), cirq.q(4, 2)
>> circuit = cirq.Circuit(cirq.CZ.on(q0, q1))
>> cirq.DensityMatrixSimulator(noise=noise_model).simulate(circuit)
measurements: (no measurements)
qubits: (cirq.GridQubit(4, 1), cirq.GridQubit(4, 2))
final density matrix:
[[1.+0.j 0.+0.j 0.+0.j 0.+0.j]
[0.+0.j 0.+0.j 0.+0.j 0.+0.j]
[0.+0.j 0.+0.j 0.+0.j 0.+0.j]
[0.+0.j 0.+0.j 0.+0.j 0.+0.j]]
phase:
final density matrix:
[[1.+0.j]]you may also want to call noise_props.expected_gates() to see which gates are supported by the device and if your circuit contains an unsupported gate then you can compile your circuit to the target gateset using cirq.optimize_for_target_gateset
cosenal
Description of the issue
I wanted to use the noise model described in https://quantumai.google/cirq/simulate/noisy_simulation#simulation_with_realistic_noise in the simulation of a very simple circuit (one C-Z gate, nothing else), but it throws a KeyError (see traceback below).
How to reproduce the issue
The same snippet works if I set
noise=None, or if the circuit has a CNOT instead of a CZ gate.Traceback:
Cirq version 1.3.0