def identity(cls, space):
if type(space) is int:
n = space
space = Space((n, n), 'ud')
A = cls(space.shape)
assert space.is_square(), space
for i in range(space.shape[0]):
A[i, i] = 1.
return A
def random_hermitian(cls, space):
if type(space) is int:
n = space
space = Space((n, n), 'ud')
assert space.is_square()
A = Qu.random(space.shape, space.valence)
A = A.dag() * A
A = Gate.promote(A)
return A
def random_unitary(cls, space):
vs = []
if type(space) is int:
n = space
space = Space((n, n), 'ud')
assert space.is_square()
n = space.shape[0]
U = Gate(space.shape)
for i in range(n):
v = Qu.random(n, 'u')
for u in vs:
r = u.dag() * v
v -= r * u
#assert abs((u.transpose() * v)) < 1e-10
v.normalize()
vs.append(v)
U[i, :] = v
return U