class ControlEnvironment(ctrl_qubits, ctrl_state=- 1, ctrl_method=None, invert=False)[source]#

This class behaves similarly to ConditionEnvironment but instead of a function calculating a truth value, we supply a list of qubits. The environment’s content is then controlled on these qubits.

An alias for this QuantumEnvironment is “control”.


A list of qubits on which to control the environment’s content.

ctrl_stateint/str, optional

The computational basis state which is supposed to activate the environment. Can be supplied as a bitstring or integer. The default is “1111..”.


We create a QuantumVariable and control on some of it’s qubits using the control alias

from qrisp import QuantumVariable, QuantumString, multi_measurement, control, h

qv = QuantumVariable(3)
q_str = QuantumString()

qv[:] = "011"

with control(qv[:2], "11"):
    q_str += "hello world"
>>> print(multi_measurement([qv, q_str]))
{('011', 'aaaaaaaaaaa'): 0.5, ('111', 'hello world'): 0.5}