from qlazy import QState, DensOp
qs_pure = QState(1).h(0) # (|0> + |1>) / sqrt(2.0)
de_pure = DensOp(qstate=[qs_pure], prob=[1.0])
qs_pure_1 = QState(1) # |0>
qs_pure_2 = QState(1).x(0) # |1>
de_mixed = DensOp(qstate=[qs_pure_1, qs_pure_2], prob=[0.5, 0.5])
print("== pure state ==")
de_pure.show()
print("* trace =", de_pure.trace())
print("* square trace =", de_pure.sqtrace())
print("")
print("== pure state (only non-zero) ==")
de_pure.show(nonzero=True)
print("* trace =", de_pure.trace())
print("* square trace =", de_pure.sqtrace())
print("")
print("== mixed state ==")
de_mixed.show()
print("* trace =", de_mixed.trace())
print("* square trace =", de_mixed.sqtrace())
print("== mixed state (only non-zero) ==")
de_mixed.show(nonzero=True)
print("* trace =", de_mixed.trace())
print("* square trace =", de_mixed.sqtrace())
print("== parameter ==")
gamma = 0.5
H = make_hamiltonian()
print("gamma =", gamma)
print("== initial density operator ==")
u_1 = math.sqrt(1 / 3)
u_2 = math.sqrt(1 / 3)
u_3 = math.sqrt(1 / 3)
D = make_densop_matrix(u_1, u_2, u_3)
de = DensOp(matrix=D)
de.show()
print("square trace =", de.sqtrace())
print("(u_1,u_2,u_3) = ({0:.3f},{1:.3f},{2:.3f})".format(u_1, u_2, u_3))
print("expect value of energy =", de.expect(matrix=H))
[M_0, M_1] = make_kraus(gamma=gamma)
print("== finail density operator ==")
de.instrument(kraus=[M_0, M_1])
de.show()
print("square trace =", de.sqtrace())
(u_1, u_2, u_3) = get_coordinate(densop=de)
print("(u_1,u_2,u_3) = ({0:.3f},{1:.3f},{2:.3f})".format(u_1, u_2, u_3))
print("expect value of energy =", de.expect(matrix=H))
de_tmp.mul(prob[i])
densop_est = de_tmp.clone()
else:
de_tmp.mul(prob[i])
densop_est.add(de_tmp)
return densop_est
if __name__ == '__main__':
# settings
qubit_num = 1
mixed_num = 2
shots = 100
# quantum state ensemble (original)
qstate, prob = random_qstate_ensemble(qubit_num, mixed_num)
# density operator (original)
densop_ori = DensOp(qstate=qstate, prob=prob)
# density operator estimation only from quantum state ensemble
# (quantum state tomography)
densop_est = estimate_densop(prob,qstate,shots)
print("** density operator (original)")
densop_ori.show()
print("** density operator (estimated)")
densop_est.show()
print("** fidelity =",densop_ori.fidelity(densop_est))