Application of deep quantum neural networks to finance

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Application of deep quantum neural networks to finance

Takayuki Sakuma
Published on 11/14/2020
Options
Derivatives
Deep learning
Machine learning
Risk management

This paper explores the application of deep quantum neural networks (DQNN) to financial problems, specifically learning implied volatilities and option prices, and computing Greeks (delta and gamma) analytically. The DQNN architecture, proposed by Beer et al. (2020), generalizes classical deep neural networks to quantum settings, using unitary operations and density matrix propagation. The author encodes financial data (e.g., strike prices, implied volatilities, option prices) into quantum states via a sigmoid-based mapping, enabling the network to learn from training pairs. Numerical experiments demonstrate that DQNN can learn implied volatilities from market data with reasonable accuracy, and increasing the number of qubits in hidden layers yields slight improvements. A key contribution is the analytical computation of Greeks: the paper derives formulas for delta and gamma using the derivative of the input density matrix and the trained DQNN, avoiding numerical differentiation. To incorporate differential learning, a modified cost function is proposed that includes fidelity terms for first and second derivatives, allowing the network to learn both option prices and their sensitivities simultaneously. The results suggest that DQNN is a promising technique for efficient risk management and derivative pricing in finance, leveraging quantum computing's potential for speedup.

Highlights

  • 1Applies deep quantum neural networks (DQNN) to financial problems like learning implied volatilities and option prices.
  • 2Demonstrates analytical computation of Greeks (delta, gamma) using DQNN, enabling efficient risk management.
  • 3Proposes a modified cost function incorporating fidelity of differentials to improve learning of option price derivatives.
  • 4Shows numerical experiments where DQNN learns implied volatilities and option prices with reasonable accuracy.

Methods

  • M
    Deep Quantum Neural Network (DQNN) architecture with feedforward and backpropagation-like parameter updates using Kraus operators.
  • M
    Encoding financial data into quantum states via sigmoid-based mapping to Bloch sphere angles.
  • M
    Differential learning framework: computing analytical derivatives of density matrices to obtain Greeks, with modifications to ensure valid quantum states.
  • M
    Cost function combining fidelity of output states and their first/second derivatives for training.

Results

  • R
    DQNN successfully learns implied volatilities from market data with one input/output qubit and one hidden layer (2 or 3 qubits).
  • R
    Increasing hidden layer qubits from 2 to 3 slightly improves performance in implied volatility learning.
  • R
    Analytical formulas for delta and gamma are derived and can be computed via DQNN without numerical differentiation.
  • R
    The proposed differential cost function enables simultaneous learning of option prices and their Greeks.
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