def floquet_master_equation_tensor(Alist, f_energies):
"""
Construct a tensor that represents the master equation in the floquet
basis (with constant Hamiltonian and collapse operators).
Simplest RWA approximation [Grifoni et al, Phys.Rep. 304 229 (1998)]
Parameters
----------
Alist : list
A list of Floquet-Markov master equation rate matrices.
f_energies : array
The Floquet energies.
Returns
-------
output : array
The Floquet-Markov master equation tensor `R`.
"""
if isinstance(Alist, list):
# Alist can be a list of rate matrices corresponding
# to different operators that couple to the environment
N, M = np.shape(Alist[0])
else:
# or a simple rate matrix, in which case we put it in a list
Alist = [Alist]
N, M = np.shape(Alist[0])
R = Qobj(scipy.sparse.csr_matrix((N * N, N * N)), [[N, N], [N, N]],
[N * N, N * N])
R.data = R.data.tolil()
for I in range(N * N):
a, b = vec2mat_index(N, I)
for J in range(N * N):
c, d = vec2mat_index(N, J)
R.data[I, J] = -1.0j * (f_energies[a] -
f_energies[b]) * (a == c) * (b == d)
for A in Alist:
s1 = s2 = 0
for n in range(N):
s1 += A[a, n] * (n == c) * (n == d) - A[n, a] * (
a == c) * (a == d)
s2 += (A[n, a] + A[n, b]) * (a == c) * (b == d)
dR = (a == b) * s1 - 0.5 * (1 - (a == b)) * s2
if dR != 0.0:
R.data[I, J] += dR
R.data = R.data.tocsr()
return R
def floquet_master_equation_tensor(Alist, f_energies):
"""
Construct a tensor that represents the master equation in the floquet
basis (with constant Hamiltonian and collapse operators).
Simplest RWA approximation [Grifoni et al, Phys.Rep. 304 229 (1998)]
Parameters
----------
Alist : list
A list of Floquet-Markov master equation rate matrices.
f_energies : array
The Floquet energies.
Returns
-------
output : array
The Floquet-Markov master equation tensor `R`.
"""
if isinstance(Alist, list):
# Alist can be a list of rate matrices corresponding
# to different operators that couple to the environment
N, M = np.shape(Alist[0])
else:
# or a simple rate matrix, in which case we put it in a list
Alist = [Alist]
N, M = np.shape(Alist[0])
R = Qobj(scipy.sparse.csr_matrix((N*N,N*N)), [[N,N], [N,N]], [N*N,N*N])
R.data=R.data.tolil()
for I in range(N*N):
a,b = vec2mat_index(N, I)
for J in range(N*N):
c,d = vec2mat_index(N, J)
R.data[I,J] = - 1.0j * (f_energies[a]-f_energies[b]) * (a == c) * (b == d)
for A in Alist:
s1 = s2 = 0
for n in range(N):
s1 += A[a,n] * (n == c) * (n == d) - A[n,a] * (a == c) * (a == d)
s2 += (A[n,a] + A[n,b]) * (a == c) * (b == d)
dR = (a == b) * s1 - 0.5 * (1 - (a == b)) * s2
if dR != 0.0:
R.data[I,J] += dR
R.data=R.data.tocsr()
return R
def _generic_ode_solve(r, psi0, tlist, expt_ops, opt, state_vectorize, state_norm_func=None):
"""
Internal function for solving ODEs.
"""
#
# prepare output array
#
n_tsteps = len(tlist)
dt = tlist[1]-tlist[0]
output = Odedata()
output.solver = "mesolve"
output.times = tlist
if isinstance(expt_ops, types.FunctionType):
n_expt_op = 0
expt_callback = True
elif isinstance(expt_ops, list):
n_expt_op = len(expt_ops)
expt_callback = False
if n_expt_op == 0:
output.states = []
else:
output.expect = []
output.num_expect = n_expt_op
for op in expt_ops:
if op.isherm and psi0.isherm:
output.expect.append(np.zeros(n_tsteps))
else:
output.expect.append(np.zeros(n_tsteps,dtype=complex))
else:
raise TypeError("Expectation parameter must be a list or a function")
#
# start evolution
#
psi = Qobj(psi0)
t_idx = 0
for t in tlist:
if not r.successful():
break;
if state_norm_func:
psi.data = state_vectorize(r.y)
state_norm = state_norm_func(psi.data)
psi.data = psi.data / state_norm
r.set_initial_value(r.y/state_norm, r.t)
else:
psi.data = state_vectorize(r.y)
if expt_callback:
# use callback method
expt_ops(t, Qobj(psi))
else:
# calculate all the expectation values, or output rho if no operators
if n_expt_op == 0:
output.states.append(Qobj(psi)) # copy psi/rho
else:
for m in range(0, n_expt_op):
output.expect[m][t_idx] = expect(expt_ops[m], psi)
r.integrate(r.t + dt)
t_idx += 1
if not opt.rhs_reuse and odeconfig.tdname != None:
try:
os.remove(odeconfig.tdname+".pyx")
except:
pass
return output
def floquet_markov_mesolve(R, ekets, rho0, tlist, e_ops, options=None):
"""
Solve the dynamics for the system using the Floquet-Markov master equation.
"""
if options == None:
opt = Odeoptions()
else:
opt=options
if opt.tidy:
R.tidyup()
#
# check initial state
#
if isket(rho0):
# Got a wave function as initial state: convert to density matrix.
rho0 = ket2dm(rho0)
#
# prepare output array
#
n_tsteps = len(tlist)
dt = tlist[1]-tlist[0]
output = Odedata()
output.times = tlist
if isinstance(e_ops, FunctionType):
n_expt_op = 0
expt_callback = True
elif isinstance(e_ops, list):
n_expt_op = len(e_ops)
expt_callback = False
if n_expt_op == 0:
output.states = []
else:
output.expect = []
output.num_expect = n_expt_op
for op in e_ops:
if op.isherm:
output.expect.append(np.zeros(n_tsteps))
else:
output.expect.append(np.zeros(n_tsteps,dtype=complex))
else:
raise TypeError("Expectation parameter must be a list or a function")
#
# transform the initial density matrix and the e_ops opterators to the
# eigenbasis: from computational basis to the floquet basis
#
if ekets != None:
rho0 = rho0.transform(ekets, True)
if isinstance(e_ops, list):
for n in np.arange(len(e_ops)): # not working
e_ops[n] = e_ops[n].transform(ekets) #
#
# setup integrator
#
initial_vector = mat2vec(rho0.full())
r = scipy.integrate.ode(cyq_ode_rhs)
r.set_f_params(R.data.data, R.data.indices, R.data.indptr)
r.set_integrator('zvode', method=opt.method, order=opt.order,
atol=opt.atol, rtol=opt.rtol,
max_step=opt.max_step)
r.set_initial_value(initial_vector, tlist[0])
#
# start evolution
#
rho = Qobj(rho0)
t_idx = 0
for t in tlist:
if not r.successful():
break;
rho.data = vec2mat(r.y)
if expt_callback:
# use callback method
e_ops(t, Qobj(rho))
else:
# calculate all the expectation values, or output rho if no operators
if n_expt_op == 0:
output.states.append(Qobj(rho)) # copy psi/rho
else:
for m in range(0, n_expt_op):
output.expect[m][t_idx] = expect(e_ops[m], rho) # basis OK?
r.integrate(r.t + dt)
t_idx += 1
return output
def tensor(*args):
"""Calculates the tensor product of input operators.
Parameters
----------
args : array_like
``list`` or ``array`` of quantum objects for tensor product.
Returns
--------
obj : qobj
A composite quantum object.
Examples
--------
>>> tensor([sigmax(), sigmax()])
Quantum object: dims = [[2, 2], [2, 2]], shape = [4, 4], type = oper, isHerm = True
Qobj data =
[[ 0.+0.j 0.+0.j 0.+0.j 1.+0.j]
[ 0.+0.j 0.+0.j 1.+0.j 0.+0.j]
[ 0.+0.j 1.+0.j 0.+0.j 0.+0.j]
[ 1.+0.j 0.+0.j 0.+0.j 0.+0.j]]
"""
if not args:
raise TypeError("Requires at least one input argument")
num_args = len(args)
step = 0
for n in range(num_args):
if isinstance(args[n], Qobj):
qos = args[n]
if step == 0:
dat = qos.data
dim = qos.dims
shp = qos.shape
step = 1
else:
dat = sp.kron(dat, qos.data,
format='csr') #sparse Kronecker product
dim = [dim[0] + qos.dims[0],
dim[1] + qos.dims[1]] #append dimensions of Qobjs
shp = [dat.shape[0], dat.shape[1]] #new shape of matrix
elif isinstance(
args[n],
(list, ndarray)): #checks if input is list/array of Qobjs
qos = args[n]
items = len(qos) #number of inputs
if not all([
isinstance(k, Qobj) for k in qos
]): #raise error if one of the inputs is not a quantum object
raise TypeError("One of inputs is not a quantum object")
if items == 1: # if only one Qobj, do nothing
if step == 0:
dat = qos[0].data
dim = qos[0].dims
shp = qos[0].shape
step = 1
else:
dat = sp.kron(dat, qos[0].data,
format='csr') #sparse Kronecker product
dim = [dim[0] + qos[0].dims[0], dim[1] + qos[0].dims[1]
] #append dimensions of Qobjs
shp = [dat.shape[0], dat.shape[1]] #new shape of matrix
elif items != 1:
if step == 0:
dat = qos[0].data
dim = qos[0].dims
shp = qos[0].shape
step = 1
for k in range(items - 1): #cycle over all items
dat = sp.kron(dat, qos[k + 1].data,
format='csr') #sparse Kronecker product
dim = [
dim[0] + qos[k + 1].dims[0],
dim[1] + qos[k + 1].dims[1]
] #append dimensions of Qobjs
shp = [dat.shape[0], dat.shape[1]] #new shape of matrix
out = Qobj()
out.data = dat
out.dims = dim
out.shape = shp
if qutip.settings.auto_tidyup:
return Qobj(out).tidyup() #returns tidy Qobj
else:
return Qobj(out)
def tensor(*args):
"""Calculates the tensor product of input operators.
Parameters
----------
args : array_like
``list`` or ``array`` of quantum objects for tensor product.
Returns
--------
obj : qobj
A composite quantum object.
Examples
--------
>>> tensor([sigmax(), sigmax()])
Quantum object: dims = [[2, 2], [2, 2]], shape = [4, 4], type = oper, isHerm = True
Qobj data =
[[ 0.+0.j 0.+0.j 0.+0.j 1.+0.j]
[ 0.+0.j 0.+0.j 1.+0.j 0.+0.j]
[ 0.+0.j 1.+0.j 0.+0.j 0.+0.j]
[ 1.+0.j 0.+0.j 0.+0.j 0.+0.j]]
"""
if not args:
raise TypeError("Requires at least one input argument")
num_args=len(args)
step=0
for n in range(num_args):
if isinstance(args[n],Qobj):
qos=args[n]
if step==0:
dat=qos.data
dim=qos.dims
shp=qos.shape
step=1
else:
dat=sp.kron(dat,qos.data, format='csr') #sparse Kronecker product
dim=[dim[0]+qos.dims[0],dim[1]+qos.dims[1]] #append dimensions of Qobjs
shp=[dat.shape[0],dat.shape[1]] #new shape of matrix
elif isinstance(args[n],(list,ndarray)):#checks if input is list/array of Qobjs
qos=args[n]
items=len(qos) #number of inputs
if not all([isinstance(k,Qobj) for k in qos]): #raise error if one of the inputs is not a quantum object
raise TypeError("One of inputs is not a quantum object")
if items==1:# if only one Qobj, do nothing
if step==0:
dat=qos[0].data
dim=qos[0].dims
shp=qos[0].shape
step=1
else:
dat=sp.kron(dat,qos[0].data, format='csr') #sparse Kronecker product
dim=[dim[0]+qos[0].dims[0],dim[1]+qos[0].dims[1]] #append dimensions of Qobjs
shp=[dat.shape[0],dat.shape[1]] #new shape of matrix
elif items!=1:
if step==0:
dat=qos[0].data
dim=qos[0].dims
shp=qos[0].shape
step=1
for k in range(items-1): #cycle over all items
dat=sp.kron(dat,qos[k+1].data, format='csr') #sparse Kronecker product
dim=[dim[0]+qos[k+1].dims[0],dim[1]+qos[k+1].dims[1]] #append dimensions of Qobjs
shp=[dat.shape[0],dat.shape[1]] #new shape of matrix
out=Qobj()
out.data=dat
out.dims=dim
out.shape=shp
if qutip.settings.auto_tidyup:
return Qobj(out).tidyup() #returns tidy Qobj
else:
return Qobj(out)
def bloch_redfield_solve(R, ekets, rho0, tlist, e_ops=[], options=None):
"""
Evolve the ODEs defined by Bloch-Redfield master equation. The
Bloch-Redfield tensor can be calculated by the function
:func:`bloch_redfield_tensor`.
Parameters
----------
R : :class:`qutip.Qobj`
Bloch-Redfield tensor.
ekets : array of :class:`qutip.Qobj`
Array of kets that make up a basis tranformation for the eigenbasis.
rho0 : :class:`qutip.Qobj`
Initial density matrix.
tlist : *list* / *array*
List of times for :math:`t`.
e_ops : list of :class:`qutip.Qobj` / callback function
List of operators for which to evaluate expectation values.
options : :class:`qutip.Qdeoptions`
Options for the ODE solver.
Returns
-------
output: :class:`qutip.Odedata`
An instance of the class :class:`qutip.Odedata`, which contains either
an *array* of expectation values for the times specified by `tlist`.
"""
if options == None:
options = Odeoptions()
options.nsteps = 2500 #
if options.tidy:
R.tidyup()
#
# check initial state
#
if isket(rho0):
# Got a wave function as initial state: convert to density matrix.
rho0 = rho0 * rho0.dag()
#
# prepare output array
#
n_e_ops = len(e_ops)
n_tsteps = len(tlist)
dt = tlist[1] - tlist[0]
if n_e_ops == 0:
result_list = []
else:
result_list = []
for op in e_ops:
if op.isherm and rho0.isherm:
result_list.append(np.zeros(n_tsteps))
else:
result_list.append(np.zeros(n_tsteps, dtype=complex))
#
# transform the initial density matrix and the e_ops opterators to the
# eigenbasis
#
if ekets != None:
rho0 = rho0.transform(ekets)
for n in arange(len(e_ops)):
e_ops[n] = e_ops[n].transform(ekets, False)
#
# setup integrator
#
initial_vector = mat2vec(rho0.full())
r = scipy.integrate.ode(cyq_ode_rhs)
r.set_f_params(R.data.data, R.data.indices, R.data.indptr)
r.set_integrator(
'zvode',
method=options.method,
order=options.order,
atol=options.atol,
rtol=options.rtol, #nsteps=options.nsteps,
#first_step=options.first_step, min_step=options.min_step,
max_step=options.max_step)
r.set_initial_value(initial_vector, tlist[0])
#
# start evolution
#
rho = Qobj(rho0)
t_idx = 0
for t in tlist:
if not r.successful():
break
rho.data = vec2mat(r.y)
# calculate all the expectation values, or output rho if no operators
if n_e_ops == 0:
result_list.append(Qobj(rho))
else:
for m in range(0, n_e_ops):
result_list[m][t_idx] = expect(e_ops[m], rho)
r.integrate(r.t + dt)
t_idx += 1
return result_list
def bloch_redfield_solve(R, ekets, rho0, tlist, e_ops=[], options=None):
"""
Evolve the ODEs defined by Bloch-Redfield master equation. The
Bloch-Redfield tensor can be calculated by the function
:func:`bloch_redfield_tensor`.
Parameters
----------
R : :class:`qutip.Qobj`
Bloch-Redfield tensor.
ekets : array of :class:`qutip.Qobj`
Array of kets that make up a basis tranformation for the eigenbasis.
rho0 : :class:`qutip.Qobj`
Initial density matrix.
tlist : *list* / *array*
List of times for :math:`t`.
e_ops : list of :class:`qutip.Qobj` / callback function
List of operators for which to evaluate expectation values.
options : :class:`qutip.Qdeoptions`
Options for the ODE solver.
Returns
-------
output: :class:`qutip.Odedata`
An instance of the class :class:`qutip.Odedata`, which contains either
an *array* of expectation values for the times specified by `tlist`.
"""
if options == None:
options = Odeoptions()
options.nsteps = 2500 #
if options.tidy:
R.tidyup()
#
# check initial state
#
if isket(rho0):
# Got a wave function as initial state: convert to density matrix.
rho0 = rho0 * rho0.dag()
#
# prepare output array
#
n_e_ops = len(e_ops)
n_tsteps = len(tlist)
dt = tlist[1]-tlist[0]
if n_e_ops == 0:
result_list = []
else:
result_list = []
for op in e_ops:
if op.isherm and rho0.isherm:
result_list.append(np.zeros(n_tsteps))
else:
result_list.append(np.zeros(n_tsteps,dtype=complex))
#
# transform the initial density matrix and the e_ops opterators to the
# eigenbasis
#
if ekets != None:
rho0 = rho0.transform(ekets)
for n in arange(len(e_ops)):
e_ops[n] = e_ops[n].transform(ekets, False)
#
# setup integrator
#
initial_vector = mat2vec(rho0.full())
r = scipy.integrate.ode(cyq_ode_rhs)
r.set_f_params(R.data.data, R.data.indices, R.data.indptr)
r.set_integrator('zvode', method=options.method, order=options.order,
atol=options.atol, rtol=options.rtol, #nsteps=options.nsteps,
#first_step=options.first_step, min_step=options.min_step,
max_step=options.max_step)
r.set_initial_value(initial_vector, tlist[0])
#
# start evolution
#
rho = Qobj(rho0)
t_idx = 0
for t in tlist:
if not r.successful():
break;
rho.data = vec2mat(r.y)
# calculate all the expectation values, or output rho if no operators
if n_e_ops == 0:
result_list.append(Qobj(rho))
else:
for m in range(0, n_e_ops):
result_list[m][t_idx] = expect(e_ops[m], rho)
r.integrate(r.t + dt)
t_idx += 1
return result_list
def _generic_ode_solve(r,
psi0,
tlist,
expt_ops,
opt,
state_vectorize,
state_norm_func=None):
"""
Internal function for solving ODEs.
"""
#
# prepare output array
#
n_tsteps = len(tlist)
dt = tlist[1] - tlist[0]
output = Odedata()
output.solver = "mesolve"
output.times = tlist
if isinstance(expt_ops, types.FunctionType):
n_expt_op = 0
expt_callback = True
elif isinstance(expt_ops, list):
n_expt_op = len(expt_ops)
expt_callback = False
if n_expt_op == 0:
output.states = []
else:
output.expect = []
output.num_expect = n_expt_op
for op in expt_ops:
if op.isherm and psi0.isherm:
output.expect.append(np.zeros(n_tsteps))
else:
output.expect.append(np.zeros(n_tsteps, dtype=complex))
else:
raise TypeError("Expectation parameter must be a list or a function")
#
# start evolution
#
psi = Qobj(psi0)
t_idx = 0
for t in tlist:
if not r.successful():
break
if state_norm_func:
psi.data = state_vectorize(r.y)
state_norm = state_norm_func(psi.data)
psi.data = psi.data / state_norm
r.set_initial_value(r.y / state_norm, r.t)
else:
psi.data = state_vectorize(r.y)
if expt_callback:
# use callback method
expt_ops(t, Qobj(psi))
else:
# calculate all the expectation values, or output rho if no operators
if n_expt_op == 0:
output.states.append(Qobj(psi)) # copy psi/rho
else:
for m in range(0, n_expt_op):
output.expect[m][t_idx] = expect(expt_ops[m], psi)
r.integrate(r.t + dt)
t_idx += 1
if not opt.rhs_reuse and odeconfig.tdname != None:
try:
os.remove(odeconfig.tdname + ".pyx")
except:
pass
return output
def floquet_markov_mesolve(R, ekets, rho0, tlist, e_ops, options=None):
"""
Solve the dynamics for the system using the Floquet-Markov master equation.
"""
if options == None:
opt = Odeoptions()
else:
opt = options
if opt.tidy:
R.tidyup()
#
# check initial state
#
if isket(rho0):
# Got a wave function as initial state: convert to density matrix.
rho0 = ket2dm(rho0)
#
# prepare output array
#
n_tsteps = len(tlist)
dt = tlist[1] - tlist[0]
output = Odedata()
output.times = tlist
if isinstance(e_ops, FunctionType):
n_expt_op = 0
expt_callback = True
elif isinstance(e_ops, list):
n_expt_op = len(e_ops)
expt_callback = False
if n_expt_op == 0:
output.states = []
else:
output.expect = []
output.num_expect = n_expt_op
for op in e_ops:
if op.isherm:
output.expect.append(np.zeros(n_tsteps))
else:
output.expect.append(np.zeros(n_tsteps, dtype=complex))
else:
raise TypeError("Expectation parameter must be a list or a function")
#
# transform the initial density matrix and the e_ops opterators to the
# eigenbasis: from computational basis to the floquet basis
#
if ekets != None:
rho0 = rho0.transform(ekets, True)
if isinstance(e_ops, list):
for n in np.arange(len(e_ops)): # not working
e_ops[n] = e_ops[n].transform(ekets) #
#
# setup integrator
#
initial_vector = mat2vec(rho0.full())
r = scipy.integrate.ode(cyq_ode_rhs)
r.set_f_params(R.data.data, R.data.indices, R.data.indptr)
r.set_integrator('zvode',
method=opt.method,
order=opt.order,
atol=opt.atol,
rtol=opt.rtol,
max_step=opt.max_step)
r.set_initial_value(initial_vector, tlist[0])
#
# start evolution
#
rho = Qobj(rho0)
t_idx = 0
for t in tlist:
if not r.successful():
break
rho.data = vec2mat(r.y)
if expt_callback:
# use callback method
e_ops(t, Qobj(rho))
else:
# calculate all the expectation values, or output rho if no operators
if n_expt_op == 0:
output.states.append(Qobj(rho)) # copy psi/rho
else:
for m in range(0, n_expt_op):
output.expect[m][t_idx] = expect(e_ops[m],
rho) # basis OK?
r.integrate(r.t + dt)
t_idx += 1
return output
