def get_circuit_params(self, steps):
learner = CircuitLearnerTF(hyperparams=self.hyperp)
learner.train_circuit(X=self.X, Y=self.Y, steps=steps)
params = learner.get_circuit_parameters()
param_value = params['regularized/dummy']
return param_value
class MaxCutSolver():
"""This method allows to embed graphs as """
def __init__(self, learner_params, training_params, matrices, gates_structure, log=None):
self.learner_params = learner_params
self.learner_params['loss'] = self.loss_function
self.learner_params['regularizer'] = self.regularizer
self.training_params = training_params
self.gates_structure = gates_structure
self.adj_matrix = matrices[0]
self.interferometer_matrix = matrices[1]
self.n_qumodes = self.adj_matrix.shape[0]
self.cost_array = self.prepare_cost_array()
self.learner_params['circuit'] = self.create_circuit_evaluator
self.learner = CircuitLearner(hyperparams=self.learner_params, model_dir=training_params['model_dir'])
self.final_params = None
if log is None:
self.log = {}
else:
self.log = log
def train_and_evaluate_circuit(self, verbose=False):
self.learner.train_circuit(steps=self.training_params['steps'], tensors_to_log=self.log)
final_params = self.learner.get_circuit_parameters()
if verbose:
for name, value in final_params.items():
print("Parameter {} has the final value {}.".format(name, value))
for gate in self.gates_structure:
gate_name = gate[2]['name']
for param_name in final_params:
if gate_name in param_name:
final_value = final_params[param_name]
gate[2]['constant'] = final_value
break
self.final_params = final_params
all_results = []
circuit_output = self.get_circuit_output()
cost_tensor = self.loss_function(circuit_output)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
circuit_output = sess.run(circuit_output)
cost_value = sess.run(cost_tensor)
if verbose:
print("Total cost:", cost_value)
return cost_value, circuit_output
def create_circuit_evaluator(self):
return self.get_circuit_output()
def build_circuit(self):
params_counter = 0
sgates = []
dgates = []
kgates = []
for gate_structure in self.gates_structure:
if gate_structure[0] is Sgate:
sgates.append(ParametrizedGate(gate_structure[0], gate_structure[1], [make_param(**gate_structure[2]), make_param(**gate_structure[3])]))
if gate_structure[0] is Dgate:
dgates.append(ParametrizedGate(gate_structure[0], gate_structure[1], [make_param(**gate_structure[2]), make_param(**gate_structure[3])]))
if gate_structure[0] is Kgate:
kgates.append(ParametrizedGate(gate_structure[0], gate_structure[1], [make_param(**gate_structure[2])]))
eng, q = sf.Engine(self.n_qumodes)
rl, U = takagi(self.adj_matrix)
initial_squeezings = np.tanh(rl)
with eng:
for i ,squeeze_value in enumerate(initial_squeezings):
Sgate(squeeze_value) | i
Interferometer(U) | q
for gate in sgates:
gate.gate(gate.params[0], gate.params[1]) | gate.qumodes
Interferometer(self.interferometer_matrix) | q
for gate in dgates:
gate.gate(gate.params[0], gate.params[1]) | gate.qumodes
Interferometer(self.interferometer_matrix) | q
for gate in kgates:
gate.gate(gate.params[0]) | gate.qumodes
circuit = {}
circuit['eng'] = eng
circuit['q'] = q
return circuit
def get_circuit_output(self, test=False):
circuit = self.build_circuit()
eng = circuit['eng']
encoding = []
state = eng.run('tf', cutoff_dim=self.training_params['cutoff_dim'], eval=False)
all_probs = state.all_fock_probs()
circuit_output = all_probs
trace = tf.identity(tf.abs(state.trace()), name='trace')
tf.summary.scalar(name='trace', tensor=trace)
if test:
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
all_probs_num = sess.run(all_probs)
pdb.set_trace()
return circuit_output
def loss_function(self, circuit_output, use_reduced_probs=True):
if use_reduced_probs:
cost_array = self.cost_array[[slice(2)]*self.n_qumodes]
cost_tensor = tf.constant(cost_array, dtype=tf.float32, name='cost_tensor')
circuit_output = tf.slice(circuit_output, [0]*self.n_qumodes, [2]*self.n_qumodes)
else:
cost_tensor = tf.constant(self.cost_array, dtype=tf.float32, name='cost_tensor')
weighted_cost_tensor = tf.multiply(cost_tensor, circuit_output)
total_probability = tf.reduce_sum(circuit_output)
result = tf.reduce_sum(weighted_cost_tensor)
result = tf.divide(result, total_probability)
result = tf.multiply(result, tf.constant(-1.0))
return result
def regularizer(self, regularized_params):
return tf.nn.l2_loss(regularized_params)
def calculate_cost_once(self, encoding):
cost_value = 0
for i in range(len(encoding)):
for j in range(len(encoding)):
cost_value += 0.5 * self.adj_matrix[i][j] * (encoding[i] - encoding[j])**2
return cost_value
def assess_all_solutions_clasically(self):
all_possible_solutions = list(itertools.product([0, 1], repeat=len(self.adj_matrix)))
for solution in all_possible_solutions:
print(solution, self.calculate_cost_once(solution))
def prepare_cost_array(self):
cutoff = self.training_params['cutoff_dim']
cost_array = np.zeros([cutoff] * self.n_qumodes)
for indices in np.ndindex(cost_array.shape):
cost_array[indices] = self.calculate_cost_once(np.clip(indices,0,1))
return cost_array
class MaxCutSolver():
"""
The MaxCut solver algorithm.
The MaxCut problem seeks to find the maximum number of edges on a graph that when cut, each exactly once,
their total weight is closest to the total weight of the graph edges.
The problem is known to be NP-complete hence the search for solutions that allow us to solve it
for larger graphs.
This class allows embedding the graph as a quantum circuit and finding the maximum cut of the embedded graph.
For reference, you can also calculate all solutions classically.
Using this class:
1) initialize with `solver = MaxCutSolver(learner_params, training_params, matrices, gates_structure, log=log)` where
`learner_params` is a dictionary holding parameters that pertains to optimization,
`training_params` is a dictionary that indicates the steps to be taken by the optimizer and the cutoff dimension of the results,
`matrices` is a list of the graph adjacency matrix and the interferometer matrix,
`gates_structures` is a list that contains configuration options (parameters) for various gates and
`log` is a dictionary of settings for logging.
2) call `solver.train_and_evaluate_circuit()` to train and evaluate the circuit.
3) call `solver.assess_all_solutions_clasically()` to get all solutions classically.
:learner_params: (dict) dictionary of the learner parameters. The expected fields are:
- `task`: (str) selected `optimization` to solve the maxcut problem as an optimization problem.
- `regularization_strength`: (float) a low value (about 1e-5) for regularization strength.
- `optimizer`: (str) the optimizer to use such `SGD` for stochastic gradient descent.
- `init_learning_rate`: (float) the initial learning rate of the optimizer such as 0.1.
- `log_every`: (float) the logging interval in seconds.
:training_params: (dict) dictionary of settings that pertain to training. These settings control the amount of
resources that will used to solve the problem and are dependent of the graph size. The expected fields are:
- `steps`: (int) the number of steps the optimizer is to run for.
- `cutoff_dim`: (int) cap on the results of the algorithm.
:matrices: (list) list containing the adjacency matrix at index `0` and the interferometer matrix at index `1`.
:gate_structures: (list) list of lists where each such list contains configuration of a gate parameters.
An example of such a list is `[Sgate, 0, {"constant": np.random.random() - 0.5, "name": 'squeeze_0', 'regularize': True, 'monitor': True}]`
where we seek to configure the squeeze gate.
"""
def __init__(self,
learner_params,
training_params,
matrices,
gates_structure,
log=None):
self.learner_params = learner_params
self.learner_params["loss"] = self._loss_function
self.learner_params["_regularizer"] = self._regularizer
self.training_params = training_params
self.gates_structure = gates_structure
self.adj_matrix = matrices[0]
self.interferometer_matrix = matrices[1]
self.n_qumodes = self.adj_matrix.shape[0]
self.cost_array = self._prepare_cost_array()
self.learner = None
if log is None:
self.log = {}
else:
self.log = log
def train_and_evaluate_circuit(self):
"""
Training and evalutation of the circuit.
%TODO: Give an explanation of how this training and evaluation happens for users.
"""
self.learner_params['circuit'] = self._create_circuit_evaluator
self.learner = CircuitLearner(hyperparams=self.learner_params)
self.learner.train_circuit(steps=self.training_params["steps"],
tensors_to_log=self.log)
final_params = self.learner.get_circuit_parameters()
for name, value in final_params.items():
if "Variable" not in name:
print("Parameter {} has the final value {}.".format(
name, value))
for gate in self.gates_structure:
gate_name = gate[2]["name"]
for param_name in final_params:
if gate_name in param_name:
final_value = final_params[param_name]
gate[2]["constant"] = final_value
break
all_results = []
circuit_output = self._get_circuit_output()
cost_tensor = self._loss_function(circuit_output)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
circuit_output = sess.run(circuit_output)
cost_value = sess.run(cost_tensor)
print("Total cost:", cost_value)
return cost_value
def assess_all_solutions_clasically(self):
"""
Training and evalutation of the circuit.
%TODO: Give an explanation of how this assessment happens for users.
"""
all_possible_solutions = list(
itertools.product([0, 1], repeat=len(self.adj_matrix)))
for solution in all_possible_solutions:
print(solution, self._calculate_cost_once(solution))
def _create_circuit_evaluator(self):
return self._get_circuit_output()
def _build_circuit(self):
params_counter = 0
sgates = []
dgates = []
kgates = []
for gate_structure in self.gates_structure:
if gate_structure[0] is Sgate:
sgates.append(
ParametrizedGate(gate_structure[0], gate_structure[1],
[make_param(**gate_structure[2])]))
if gate_structure[0] is Dgate:
dgates.append(
ParametrizedGate(gate_structure[0], gate_structure[1],
[make_param(**gate_structure[2])]))
if gate_structure[0] is Kgate:
kgates.append(
ParametrizedGate(gate_structure[0], gate_structure[1],
[make_param(**gate_structure[2])]))
eng, q = sf.Engine(self.n_qumodes)
rl, U = takagi(self.adj_matrix)
initial_squeezings = np.tanh(rl)
with eng:
for i, squeeze_value in enumerate(initial_squeezings):
Sgate(squeeze_value) | i
Interferometer(U) | q
for gate in sgates:
gate.gate(gate.params[0]) | gate.qumodes
Interferometer(self.interferometer_matrix) | q
for gate in dgates:
gate.gate(gate.params[0]) | gate.qumodes
Interferometer(self.interferometer_matrix) | q
for gate in kgates:
gate.gate(gate.params[0]) | gate.qumodes
circuit = {}
circuit["eng"] = eng
circuit["q"] = q
return circuit
def _get_circuit_output(self, test=False):
circuit = self._build_circuit()
eng = circuit['eng']
encoding = []
state = eng.run('tf',
cutoff_dim=self.training_params["cutoff_dim"],
eval=False)
all_probs = state.all_fock_probs()
circuit_output = all_probs
trace = tf.identity(state.trace(), name="trace")
if test:
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
all_probs_num = sess.run(all_probs)
pdb.set_trace()
return circuit_output
def _loss_function(self, circuit_output):
cost_tensor = tf.constant(self.cost_array,
dtype=tf.float32,
name="cost_tensor")
weighted_cost_tensor = tf.multiply(cost_tensor, circuit_output)
result = tf.reduce_sum(weighted_cost_tensor)
result = tf.multiply(result, tf.constant(-1.0))
return result
def _regularizer(self, regularized_params):
return tf.nn.l2_loss(regularized_params)
def _calculate_cost_once(self, encoding):
cost_value = 0
for i in range(len(encoding)):
for j in range(len(encoding)):
cost_value += 0.5 * self.adj_matrix[i][j] * (encoding[i] -
encoding[j])**2
return cost_value
def _prepare_cost_array(self):
cutoff = self.training_params["cutoff_dim"]
cost_array = np.zeros([cutoff] * self.n_qumodes)
for indices in np.ndindex(cost_array.shape):
cost_array[indices] = self._calculate_cost_once(
np.clip(indices, 0, 1))
return cost_array
hyperparams = {
'circuit': circuit,
'task': 'optimization',
'loss': myloss,
'regularizer': myregularizer,
'regularization_strength': 0.5,
'optimizer': 'SGD',
'init_learning_rate': 0.1
}
learner = CircuitLearner(hyperparams=hyperparams)
# Define the tensors we want displayed in the training log that gets printed,
# and a name to display it.
log = {'Prob': 'prob', 'Trace': 'trace'}
learner.train_circuit(steps=50, tensors_to_log=log)
# Print out the final parameters
final_params = learner.get_circuit_parameters()
# final_params is a dictionary
for name, value in final_params.items():
print("Parameter {} has the final value {}.".format(name, value))
# To monitor the training, install tensorboard, navigate with a terminal to the directory that contains
# the newly created folder "logAUTO" and run "tensorboard --logdir=logAUTO". This should return a link
# which can be opened in a browser.
# You can track the changes in the variable alpha. Tensorboard gets live updated if you rerun this script.
# Play around with the 'regularization_strength' and see how a large value forces alpha to zero.
return tf.nn.l2_loss(regularized_params)
X_train = np.array([[0, 1], [0, 2], [0, 3], [0, 4]])
hyperparams = {
'circuit': circuit,
'task': 'unsupervised',
'optimizer': 'SGD',
'init_learning_rate': 0.1,
'loss': myloss,
'regularizer': myregularizer,
'regularization_strength': 0.1
}
learner = CircuitLearner(hyperparams=hyperparams)
learner.train_circuit(X=X_train, steps=steps)
outcomes = learner.run_circuit()
final_distribution = outcomes['outputs']
# Use a helper function to sample fock states from this state.
# They should show a similar distribution to the training data
for i in range(10):
sample = sample_from_distribution(distribution=final_distribution)
print("Fock state sample {}:{} \n".format(i, sample))
# Print out the final circuit parameters
learner.get_circuit_parameters(only_print=True)
class MaxCutSolver():
"""This method allows to embed graphs as """
def __init__(self,
learner_params,
training_params,
adj_matrices,
gates_structure,
log=None):
self.learner_params = learner_params
self.learner_params['loss'] = self.loss_function
self.learner_params['regularizer'] = self.regularizer
self.training_params = training_params
self.gates_structure = gates_structure
self.adj_matrices = adj_matrices
interferometer_matrix = \
np.array(
[[1, -1, 1, -1],
[1, 1, 1, 1],
[-1, -1, 1, 1],
[1, -1, -1, 1]
]) / 2
self.interferometer_matrix = interferometer_matrix
self.n_qumodes = self.adj_matrices[0].shape[0]
self.learner_params['circuit'] = self.create_circuit_evaluator
self.learner = CircuitLearner(adj_matrices=self.adj_matrices,
hyperparams=self.learner_params,
model_dir=training_params['model_dir'])
self.final_params = None
if log is None:
self.log = {}
else:
self.log = log
def train_and_evaluate_circuit(self, verbose=True):
self.learner.train_circuit(steps=self.training_params['steps'],
tensors_to_log=self.log)
final_params = self.learner.get_circuit_parameters()
if verbose:
for name, value in final_params.items():
print("Parameter {} has the final value {}.".format(
name, value))
for gate in self.gates_structure:
for gate_element_id in range(len(gate)):
if gate_element_id < 2:
continue
gate_name = gate[gate_element_id]['name']
for param_name in final_params:
if gate_name in param_name:
final_value = final_params[param_name]
gate[gate_element_id]['constant'] = final_value
break
self.final_params = final_params
all_results = []
circuit_outputs = []
cost_values = []
for adj_matrix in self.adj_matrices:
circuit_output = self.get_circuit_output(adj_matrix)
cost_tensor = self.loss_function([circuit_output], [adj_matrix])
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
circuit_output = sess.run(circuit_output)
cost_value = sess.run(cost_tensor)
circuit_outputs.append(circuit_output)
cost_values.append(cost_value)
if verbose:
print("Total cost:", cost_value)
return cost_values, circuit_outputs
def create_circuit_evaluator(self, adj_matrix):
return self.get_circuit_output(adj_matrix)
def build_circuit(self, adj_matrix):
params_counter = 0
number_of_layers = 2
all_sgates = [[]] * number_of_layers
all_dgates = [[]] * number_of_layers
all_kgates = [[]] * number_of_layers
all_vgates = [[]] * number_of_layers
for gate_structure in self.gates_structure:
current_layer = int(gate_structure[2]['name'].split('_')[-1][0])
if gate_structure[0] is Sgate:
current_gate = ParametrizedGate(
gate_structure[0], gate_structure[1], [
make_param(**gate_structure[2]),
make_param(**gate_structure[3])
])
all_sgates[current_layer].append(current_gate)
if gate_structure[0] is Dgate:
current_gate = ParametrizedGate(
gate_structure[0], gate_structure[1], [
make_param(**gate_structure[2]),
make_param(**gate_structure[3])
])
all_dgates[current_layer].append(current_gate)
if gate_structure[0] is Kgate:
current_gate = ParametrizedGate(
gate_structure[0], gate_structure[1],
[make_param(**gate_structure[2])])
all_kgates[current_layer].append(current_gate)
if gate_structure[0] is Vgate:
current_gate = ParametrizedGate(
gate_structure[0], gate_structure[1],
[make_param(**gate_structure[2])])
all_vgates[current_layer].append(current_gate)
eng, q = sf.Engine(self.n_qumodes)
rl, U = takagi(adj_matrix)
initial_squeezings = np.arctanh(rl)
with eng:
for i, squeeze_value in enumerate(initial_squeezings):
Sgate(squeeze_value) | i
Interferometer(U) | q
for layer in range(number_of_layers):
sgates = all_sgates[layer]
dgates = all_dgates[layer]
kgates = all_kgates[layer]
vgates = all_vgates[layer]
if len(sgates) != 0:
Interferometer(self.interferometer_matrix) | q
for gate in sgates:
gate.gate(gate.params[0],
gate.params[1]) | gate.qumodes
if len(dgates) != 0:
Interferometer(self.interferometer_matrix) | q
for gate in dgates:
gate.gate(gate.params[0],
gate.params[1]) | gate.qumodes
for gate in kgates:
gate.gate(gate.params[0]) | gate.qumodes
for gate in vgates:
gate.gate(gate.params[0]) | gate.qumodes
circuit = {}
circuit['eng'] = eng
circuit['q'] = q
return circuit
def get_circuit_output(self, adj_matrix, test=False):
circuit = self.build_circuit(adj_matrix)
eng = circuit['eng']
encoding = []
state = eng.run('tf',
cutoff_dim=self.training_params['cutoff_dim'],
eval=False)
all_probs = state.all_fock_probs()
circuit_output = all_probs
trace = tf.identity(tf.abs(state.trace()), name='trace')
tf.summary.scalar(name='trace', tensor=trace)
if test:
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
all_probs_num = sess.run(all_probs)
pdb.set_trace()
return circuit_output
def loss_function(self, circuit_outputs, adj_matrices):
result = tf.constant(0, dtype=tf.float32)
for circuit_output, adj_matrix in zip(circuit_outputs, adj_matrices):
result = tf.add(
result, self.single_loss_function(circuit_output, adj_matrix))
return result
def single_loss_function(self, circuit_output, adj_matrix):
cost_tensor = tf.constant(self.prepare_cost_array(adj_matrix),
dtype=tf.float32,
name='cost_tensor')
weighted_cost_tensor = tf.multiply(cost_tensor, circuit_output)
result = tf.reduce_sum(weighted_cost_tensor)
result = tf.multiply(result, tf.constant(-1.0))
return result
def regularizer(self, regularized_params):
return tf.nn.l2_loss(regularized_params)
def prepare_cost_array(self, adj_matrix):
cutoff = self.training_params['cutoff_dim']
cost_array = np.zeros([cutoff] * self.n_qumodes)
for indices in np.ndindex(cost_array.shape):
cost_array[indices] = calculate_cost_once(np.clip(indices, 0, 1),
adj_matrix)
return cost_array