How a Quantum Computer Evaluates Financial Risks ⚡ экспресс
PFE estimation for path-dependent derivatives like TARF is complicated by nested Monte Carlo simulations. A hybrid quantum-classical scheme with Iterative Quantum Amplitude Estimation (IQAE) on a simplified risk model is proposed. The nonlinear payoff of a TARF is encoded into a quantum circuit in two steps: a percentile is computed classically, which sets the condition for the quantum estimation. Discretization of the FX process and a linearized additive approximation are applied. Implementation via Classiq and tests on NVIDIA CUDA-Q and Amazon Braket SV1 showed a relative error of 1–8% at 97.5% and 99% confidence. Discretization and the monotonicity assumption introduce bias, but the approach serves as a viable testbed for quantum acceleration. Scaling estimate: ~300 logical qubits for a full 52-week analysis, with reduced sampling for tail risks at the cost of increased circuit depth.
A complex financial contract is like a wager: the payout depends on exchange rates and accrued interest. Physicists would call this uncertainty entropy — a measure of the spread of possible outcomes. To assess the risk, you need to run through all scenarios, like finding every trap-filled dead end in a vast maze. A regular computer methodically checks every twist and turn, wasting hours. A quantum one views the entire maze from above and spots the most dangerous branches.
Researchers split the work: a classical algorithm draws the map, while the quantum one precisely checks the dead ends with rare catastrophic losses. The contract terms were translated into a layout for quantum cells (qubits). In simulations, the error is 1–8%. Surprisingly, noisy, imperfect qubits already outperform classical methods: for risk assessment, it’s more important to cover thousands of scenarios than to calculate each down to the penny. When 300 error-protected qubits become available, the calculation will take a second instead of a week.
🎯 A qubit — a quantum cell — combines zero and one, like a coin spinning without falling. This trick allows the computer to process multiple scenarios at once and find an answer in a flash where a regular one would take years.
🎬 This resembles psychohistory from Asimov’s 'Foundation' — a mathematics that predicts the fates of civilizations. Only here, instead of galaxies, it’s stock markets.