If I have two independent (unentangled) qubits, let's say one in state |1> and the other one in some superposition state with equal amplitudes and arbitrary phases. If I measure the qubit that is in the superposition state (and let's say get 0), it seems that the remaining phase is kicked back to the first (non-measured) qubit. So the state of the first (non-measured) qubit changes as a result of the measurement of the second qubit. But the qubits are independent and are not supposed to know about each other and impact each other. So why is the phase transferred to the first qubit?
# some arbitrary state: theta = [np.pi/3,np.pi/4] a = 1/np.sqrt(2)*np.array([np.exp(1j*theta),np.exp(1j*theta)]) qc = QuantumCircuit(2,1) qc.x(0) qc.initialize(a,1) # set q to a qc.measure(1,0) execute(qc,svsim).result().get_statevector() # get the post-measurement state