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Hybrid Circuit–Spintronic Quantum Framework for Financial Risk Analysis with QCVaR Estimation Using Variational Quantum Algorithms and Maximum-Likelihood Amplitude Estimation Cover

Hybrid Circuit–Spintronic Quantum Framework for Financial Risk Analysis with QCVaR Estimation Using Variational Quantum Algorithms and Maximum-Likelihood Amplitude Estimation

Open Access
|Jun 2026

Figures & Tables

Figure 1.

CVaR-driven VQA workflow: classical input, variational encoding, threshold oracle, MLAE, and CVaR evaluation. Dashed lines indicate feedback and spintronic mapping. Total qubits N = n + 2.

Figure 2.

Proposed 4-qubit variational ansatz with Ry(θi) rotations and CNOT entanglement chain for encoding portfolio loss amplitudes.

Figure 3.

Conceptual spintronic view of the proposed 4-qubit Variational ansatz.

Figure 4.

Oracle Uf implemented as a multi-controlled-X (MCX) gate: the ancilla qubit flips if the input register encodes a loss L(x) ≥ τ. For τ = 8, the MSB (x3 = 1) triggers the ancilla flip, marking tail states.

Figure 5.

Conceptual spintronic view of the proposed oracle Uf.

Figure 6.

MLAE circuit for amplifying the quantum states with depth k.

Figure 7.

Conceptual spintronic MLAE architecture.

Figure 8.

Convergence of the variational quantum ansatz (VQA) during CVaR-based optimization. The smooth decay of the loss proxy indicates stable parameter adaptation within 40 iterations.

Figure 9.

Threshold oracle validation showing ancilla measurement outcomes. The state ancilla = 1 corresponds to flagged events with L(x) > 0.75.

Figure 10.

Effect of noise models on CVaR estimation error. Measurement mitigation (M3) reduces total estimation error by over 12%, confirming enhanced robustness under realistic NISQ conditions.

Figure 11.

Log-likelihood distribution for the MLAE estimator showing a sharp maximum at the true probability p∗ ≈ 0.048.

Figure 12.

Scalability of the MLAE–QCVaR framework: runtime increases approximately linearly with the number of state qubits for fixed estimation precision.

Figure 13.

CVaR sensitivity to α: consistent monotonic increase indicating proper representation of tail risk.

Figure 14.

Workflow comparison: classical → QAE → hybrid MLAE.

Figure 15.

Fidelity degradation under depolarizing and readout noise.

Figure 16.

Spintronic energy–fidelity trade-off (conceptual).

Circuit and execution metrics_

PlatformAvg. DepthFidelity
AerSimulator (ideal)981.000
AerSimulator (noisy)980.991
IBM Brisbane (real)1120.967

Quantum approaches to financial risk estimation_

AuthorsMethodCircuit DepthHardwareLimitation / Gaps
Woerner & Egger [9]QAE500–1000TheoreticalDeep circuits unsuitable for NISQ; no hardware results
Orús et al. [12]Quantum annealing200–500D-WaveLimited to small portfolios; lacks CVaR support
Herman et al. [13]VQA50–100IBM SimulatorNo scalability analysis on real datasets
Chakrabarti et al. [14]QPE + QAA600–1200TheoreticalDeep circuits not NISQ compatible; synthetic dataset only
Fontana et al. [15]VQA for VaR100–200IBM QuantumFocused only on VaR; no CVaR extension
Li & Zhang [16]Optimized QPE Oracle150–300SimulatedAssumes ideal distributions; lacks robustness test
Pérez-Salinas et al. [17]VQE200–400SimulatedHigh classical cost; limited scalability
Miyamoto & Kubo [18]Quantum walk300–600N/ALacks practical integration with CVaR pipelines
Gilles et al. [19]QAE with EVaR/RVaR500–1000NISQ SimulatorNo hardware runs; circuit depth remains a bottleneck
Matsakos & Nield [20]Quantum-enhanced Monte Carlo400–800SimulatedComplex mapping for highdimensional risks
Wu et al. [21]End-to-end QAE300–600SimulatedNo extension to American options; limited derivatives covered
Ghosh et al. [22]Dynamic Amplitude Estimation200–400SimulatedDomain-specific; lacks generalizability
Yohichi et al. [23]Quantum PDE solver300–600NoneNo quantum hardware implementation yet
Cong & Thi [24]VQA Survey100–500N/ANo empirical tests; theoretical-only
Thakkar et al. [25]Quantum ML150–300SimulatedNot integrated into enterprise-grade risk systems

Algorithmic and resource comparison_

MetricClassical MCCanonical QAEVQA+MLAE (Ours)
Sampling complexityO(1/ϵ2)O(1/ϵ)O(1/ϵ)
Circuit depth (max k)206 (–70%)
Tail-probability MAE2.1 × 10−31.7 × 10−3
CVaR error0.4%1.3%<1.1%
Total shots (K = 6)10620,4806,144
Runtime (ibm_brisbane)184 s42 s13 s

Estimated energy per logical gate using spintronic analogues_

Logical GatePhysical MechanismEnergy (fJ)
HadamardSTO precession1.9
Ry(θ)Rashba SO coupling1.7
CNOTExchange interaction2.3
MeasurementMTJ readout2.0
DOI: https://doi.org/10.2478/qic-2026-0002 | Journal eISSN: 3106-0544 | Journal ISSN: 1533-7146
Language: English
Page range: 20 - 37
Submitted on: Sep 1, 2025
Accepted on: Nov 20, 2025
Published on: Jun 4, 2026
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year

© 2026 Gayathri S. S., Muthulakshmi P., R. Palanivel, published by Cerebration Science Publishing Co., Limited
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.