Quantum agents in the Gym: a variational quantum algorithm for deep Q-learning

Description

This repository contains an implementation of the Quantum Deep Q-learning algorithm and its application to the FrozenLake and CartPole environments as in :

• Paper : Quantum agents in the Gym: a variational quantum algorithm for deep Q-learning
• Authors : Skolik, Jerbi and Dunjko
• Date : 2021

Hyperparameters

Hyperparameters	Frozen-Lake	Cart-Pole	Explanation
n_layers	5,10,15	5	number of layers
gamma	0.8	0.99	discount factor for Q-learning
w_input		True, False	train weights on the model input
w_output		True, False	train weights on the model output
lr	0.001	0.001	model parameter learning rate
lr_input		0.001	input weight learning rate
lr_output		0.1	output weight learning rate
batch_size	11	16	number of samples shown to optimizer at each update
eps_init	1.	1.	initial value for ε-greedy policy
eps_decay	0.99	0.99	decay of ε for ε -greedy policy
eps_min	0.01	0.01	minimal value of ε for ε-greedy policy
train_freq	5	10	steps in episode after which model is updated
target_freq	10	30	steps in episode after which target is updated
memory	10000	10000	size of memory for experience replay
data_reupload		True, False	use data re-uploading
loss	SmoothL1	SmoothL1	loss type : MSE, L1 or SmoothL1
optimizer	RMSprop	RMSprop	optimizer type : SGD, RMSprop, Adam, ...
total_episodes	3500	5000	total training episodes
n_eval_episodes	5	5	number episodes to evaluate the agent

Experiments

The experiments in the paper are reproduced using PyTorch for optimization, PennyLane for quantum circuits and Gym for the environments.

Training

• Option 1 : Open in Colab. You can activate the GPU in Notebook Settings.
• Option 2 : Run on local machine. First, you need to install :

$ pip install gym torch torchvision pennylane tensorboard

You can run an experiment using the following command :

$ cd cart_pole/
$ python train.py 

You can set your own hyperparameters :

$ cd cart_pole/
$ python train.py --batch_size=32

The list of hyperparameters is given above and accessible via :

$ cd cart_pole/
$ python train.py --help

To monitor the training process using tensorboard :

$ cd cart_pole/
$ python train.py
$ tensorboard --logdir logs/

The hyperparameters, checkpoints, training and evaluation metrics are saved in the logs/ folder.

Testing

You can test your agent by passing the path to your logged model.

$ cd cart_pole/
$ python test.py --path=logs/exp_name/ --n_eval_episodes=10

Trained agents are also provided in the logs folder.

$ cd cart_pole/
$ python test.py --path=logs/input_only/ --n_eval_episodes=10

Results

Cart-Pole

The circuit output is multiplied by 90 if no output weight is available.

Setting	Average Reward	Hyperparameters and Checkpoints
No Weights	181	cart_pole/logs/no_weights/
Input Weights	200	cart_pole/logs/input_only/
Output Weights	101	cart_pole/logs/output_only/
Input and Output Weights	199	cart_pole/logs/input_output/