def test_basic(self, rand_rank):
rho = qu.rand_rho(9)
ln = qu.logneg(rho, [3, 3])
for p in (0.2, 0.5, 0.8, 1.0):
rho_d = qu.dephase(rho, p, rand_rank=rand_rank)
assert qu.logneg(rho_d, [3, 3]) <= ln
assert rho_d.tr() == pytest.approx(1.0)
def test_subsystem(self):
p = qu.singlet_pairs(4)
rhoab = p.ptr([2, 2, 2, 2], [0, 1])
assert qu.logneg(rhoab, [2] * 2) > 1 - 1e-14
rhoab = p.ptr([2, 2, 2, 2], [1, 2])
assert qu.logneg(rhoab, [2] * 2) < 1e-14
rhoab = p.ptr([2, 2, 2, 2], [2, 3])
assert qu.logneg(rhoab, [2] * 2) > 1 - 1e-14
def test_entanglement(self):
rho = qu.rand_seperable([2, 3, 2], 10)
assert_allclose(qu.tr(rho), 1.0)
assert qu.isherm(rho)
assert qu.logneg(rho, [2, 6]) < 1e-12
assert qu.logneg(rho, [6, 2]) < 1e-12
rho_a = qu.ptr(rho, [2, 3, 2], 1)
el = qu.eigvalsh(rho_a)
assert np.all(el < 1 - 1e-12)
assert np.all(el > 1e-12)
def test_entanglement(self):
rho = rand_seperable([2, 3, 2], 10)
assert_almost_equal(tr(rho), 1.0)
assert isherm(rho)
assert logneg(rho, [2, 6]) < 1e-12
assert logneg(rho, [6, 2]) < 1e-12
rho_a = ptr(rho, [2, 3, 2], 1)
el = eigvals(rho_a)
assert np.all(el < 1 - 1e-12)
assert np.all(el > 1e-12)
def test_quevo_multi_compute(self, method, qtype):
ham = ham_heis(2, cyclic=False)
p0 = qu(up() & down(), qtype=qtype)
def some_quantity(t, _):
return t
def some_other_quantity(_, pt):
return logneg(pt)
evo = QuEvo(p0,
ham,
method=method,
compute={
't': some_quantity,
'logneg': some_other_quantity
})
manual_lns = []
for pt in evo.at_times(np.linspace(0, 1, 6)):
manual_lns.append(logneg(pt))
ts = evo.results['t']
lns = evo.results['logneg']
assert len(lns) >= len(manual_lns)
# check a specific value of logneg at t=0.8 was computed automatically
checked = False
for t, ln in zip(ts, lns):
if abs(t - 0.8) < 1e-12:
assert abs(ln - manual_lns[4]) < 1e-12
checked = True
assert checked
def test_logneg_approx_many_body(self, psi_mb_abc, bsz):
sysa = [0, 1, 7, 8]
sysb = [2, 3, 9]
rho_ab = psi_mb_abc.ptr(DIMS_MB, sysa + sysb)
actual_ln = logneg(rho_ab, [2] * 7, sysa=(0, 1, 4, 5))
approx_ln = logneg_subsys_approx(psi_mb_abc, DIMS_MB,
sysa=sysa, sysb=sysb, bsz=bsz)
assert_allclose(actual_ln, approx_ln, rtol=1e-1)
def test_bipartite_schmidt_state(self):
psi = MPS_rand_state(16, 5)
psid = psi.to_dense()
eln = qu.logneg(psid, [2**7, 2**9])
s_d_ket = psi.bipartite_schmidt_state(7, get='ket-dense')
ln_d_ket = qu.logneg(s_d_ket, [5, 5])
assert_allclose(eln, ln_d_ket, rtol=1e-5)
s_d_rho = psi.bipartite_schmidt_state(7, get='rho-dense')
ln_d_rho = qu.logneg(s_d_rho, [5, 5])
assert_allclose(eln, ln_d_rho, rtol=1e-5)
T_s_ket = psi.bipartite_schmidt_state(7, get='ket')
assert set(T_s_ket.inds) == {'kA', 'kB'}
assert_allclose(T_s_ket.H @ T_s_ket, 1.0)
T_s_rho = psi.bipartite_schmidt_state(7, get='rho')
assert set(T_s_rho.outer_inds()) == {'kA', 'kB', 'bA', 'bB'}
assert_allclose(T_s_rho.H @ T_s_rho, 1.0)
def test_logneg_subsys_pure(self):
p = qu.rand_ket(2**(3 + 4))
dims = (2**3, 2**4)
sysa = 0
sysb = 1
# exact 1
ln0 = qu.logneg(p, dims, 0)
# exact 2
ln1 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1e30)
assert_allclose(ln0, ln1)
# approx
ln2 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1, tol=5e-3)
assert ln1 != ln2
assert_allclose(ln1, ln2, rtol=1e-1)
def test_logneg_subsys_pure_should_swap_subsys(self):
p = qu.rand_ket(2**(5 + 2))
dims = (2**5, 2**2)
sysa = 0
sysb = 1
# exact 1
ln0 = qu.logneg(p, dims, 0)
# exact 2
ln1 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1e30)
assert_allclose(ln0, ln1)
# approx
ln2 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1, tol=0.005)
assert ln1 != ln2
assert_allclose(ln1, ln2, rtol=0.2)
def test_logneg_subsys(self):
p = qu.rand_ket(2**(2 + 3 + 1 + 2))
dims = (2**2, 2**3, 2**1, 2**2)
sysa = [0, 3]
sysb = 1
# exact 1
ln0 = qu.logneg(qu.ptr(p, dims, [0, 1, 3]), [4, 8, 4], [0, 2])
# exact 2
ln1 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1e30)
assert_allclose(ln0, ln1)
# approx
ln2 = qu.logneg_subsys(p, dims, sysa, sysb, approx_thresh=1)
assert ln1 != ln2
assert_allclose(ln1, ln2, rtol=5e-2)
def test_quevo_compute_callback(self, qtype, method):
ham = ham_heis(2, cyclic=False)
p0 = qu(up() & down(), qtype=qtype)
def some_quantity(t, pt):
return t, logneg(pt)
evo = QuEvo(p0, ham, method=method, compute=some_quantity)
manual_lns = []
for pt in evo.at_times(np.linspace(0, 1, 6)):
manual_lns.append(logneg(pt))
ts, lns = zip(*evo.results)
assert len(lns) >= len(manual_lns)
# check a specific value of logneg at t=0.8 was computed automatically
checked = False
for t, ln in zip(ts, lns):
if abs(t - 0.8) < 1e-12:
assert abs(ln - manual_lns[4]) < 1e-12
checked = True
assert checked
def test_evo_multi_compute(self, method, qtype):
ham = qu.ham_heis(2, cyclic=False)
p0 = qu.qu(qu.up() & qu.down(), qtype=qtype)
def some_quantity(t, _):
return t
def some_other_quantity(_, pt):
return qu.logneg(pt)
# check that hamiltonian gets accepted without error for all methods
def some_other_quantity_accepting_ham(t, pt, H):
return qu.logneg(pt)
compute = {
't': some_quantity,
'logneg': some_other_quantity,
'logneg_ham': some_other_quantity_accepting_ham
}
evo = qu.Evolution(p0, ham, method=method, compute=compute)
manual_lns = []
for pt in evo.at_times(np.linspace(0, 1, 6)):
manual_lns.append(qu.logneg(pt))
ts = evo.results['t']
lns = evo.results['logneg']
lns_ham = evo.results['logneg_ham']
assert len(lns) >= len(manual_lns)
# check a specific value of logneg at t=0.8 was computed automatically
checked = False
for t, ln, ln_ham in zip(ts, lns, lns_ham):
if abs(t - 0.8) < 1e-12:
assert abs(ln - manual_lns[4]) < 1e-12
# check that accepting hamiltonian didn't mess it up
assert ln == ln_ham
checked = True
assert checked
def test_logneg_approx_simple(self, psi_abc, bsz):
rho_ab = psi_abc.ptr(DIMS, [0, 1])
actual_ln = logneg(rho_ab, DIMS[:-1], 0)
approx_ln = logneg_subsys_approx(psi_abc, DIMS, 0, 1, bsz=bsz)
assert_allclose(actual_ln, approx_ln, rtol=2e-1)
def test_bell_states(self, qtype, bs):
p = qu.bell_state(bs, qtype=qtype)
assert qu.logneg(p) > 1.0 - 1e-14
def some_quantity(t, pt):
return t, logneg(pt)
def some_other_quantity(_, pt):
return logneg(pt)
def test_interleaving(self):
p = permute(singlet() & singlet(), [2, 2, 2, 2], [0, 2, 1, 3])
assert logneg(p, [2] * 4, sysa=[0, 3]) > 2 - 1e-13
def some_other_quantity_accepting_ham(t, pt, H):
return qu.logneg(pt)
def test_interleaving(self):
p = qu.permute(qu.singlet() & qu.singlet(), [2, 2, 2, 2], [0, 2, 1, 3])
assert qu.logneg(p, [2] * 4, sysa=[0, 3]) > 2 - 1e-13
