cannot save tensorrflow keras quantum model using save/pickle

Question

how to save tensorflow quantum model? I am getting the following when i am trying to save keras model with quantum circuits. I didnt find any support for the same. tensorflow:Layer add_circuit_2 was passed non-serializable keyword arguments tensorflow:Layer add_circuit_2 was passed non-serializable keyword arguments tensorflow:Layer add_circuit_2 was passed non-serializable keyword arguments

    WARNING:tensorflow:Layer add_circuit_2 was passed non-serializable keyword arguments: {'prepend': 
    cirq.Circuit([
    cirq.Moment(operations=[
    cirq.H.on(cirq.GridQubit(0, 0)),
    cirq.H.on(cirq.GridQubit(0, 1)),
    cirq.H.on(cirq.GridQubit(0, 2)),
    cirq.H.on(cirq.GridQubit(0, 3)),
    cirq.H.on(cirq.GridQubit(1, 0)),
    cirq.H.on(cirq.GridQubit(1, 1)),
    cirq.H.on(cirq.GridQubit(1, 2)),
    cirq.H.on(cirq.GridQubit(1, 3)),
    cirq.H.on(cirq.GridQubit(2, 0)),
    cirq.H.on(cirq.GridQubit(2, 1)),
    cirq.H.on(cirq.GridQubit(2, 2)),
    cirq.H.on(cirq.GridQubit(2, 3)),
    cirq.H.on(cirq.GridQubit(3, 0)),
    cirq.H.on(cirq.GridQubit(3, 1)),
    cirq.H.on(cirq.GridQubit(3, 2)),
    cirq.H.on(cirq.GridQubit(3, 3)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(0, 0), cirq.GridQubit(0, 1)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(0, 1), cirq.GridQubit(0, 2)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(0, 2), cirq.GridQubit(0, 3)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(0, 3), cirq.GridQubit(1, 0)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(1, 0), cirq.GridQubit(1, 1)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(1, 1), cirq.GridQubit(1, 2)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(1, 2), cirq.GridQubit(1, 3)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(1, 3), cirq.GridQubit(2, 0)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(2, 0), cirq.GridQubit(2, 1)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(2, 1), cirq.GridQubit(2, 2)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(2, 2), cirq.GridQubit(2, 3)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(2, 3), cirq.GridQubit(3, 0)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(3, 0), cirq.GridQubit(3, 1)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(3, 1), cirq.GridQubit(3, 2)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(3, 2), cirq.GridQubit(3, 3)),
]),
cirq.Moment(operations=[
    cirq.CZ.on(cirq.GridQubit(3, 3), cirq.GridQubit(0, 0)),
]),])}. 
They will not be included in the serialized model (and thus will be missing at deserialization time).
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-91-a74ee5c9d34d> in <module>()
----> 1 qcnn_model.save('qcnn_model.h5')

8 frames
/usr/local/lib/python3.6/dist-packages/tensorflow_core/python/keras/engine/base_layer.py in 
get_config(self)
497     # or that `get_config` has been overridden:
498     if len(extra_args) > 1 and hasattr(self.get_config, '_is_default'):
--> 499       raise NotImplementedError('Layers with arguments in `__init__` must '
500                                 'override `get_config`.')
501     return config

NotImplementedError: Layers with arguments in `__init__` must override `get_config`.

Answer 1

TensorFlow Quantum does not yet implement get_config and load_config. We had some difficulty with saving certain Cirq objects, we are working on it.

For now if you want to save models that contain quantum layers you can use the

model = tf.keras.Model(...)
model.save_weights("some_path")
...
model.load_weights("some_path")

function instead.