Vanguard Quantum Copilot

The idea

Pick exactly K assets from a large universe and allocate capital across them — without ever breaking a hard institutional guardrail. The standard quantum approach encodes "exactly K" as a QUBO penalty you tune with a knob; a penalty only encourages the rule and can silently break it.

Penalty-free selection. The quantum circuit starts in a Dicke state and every gate conserves the number of selected assets — so an out-of-mandate portfolio is physically impossible to produce (measured probability ≈ 10⁻³³).
Scales by decomposition. Hierarchical Risk Parity carves a 100-asset universe into ≤ 20-qubit clusters, coordinated by an adaptive-ρ ADMM loop with a classical convex optimizer.
Hardware-matched. The XY mixer compiles onto a degree-≤3 spanning tree that embeds on a heavy-hex lattice with zero SWAP routing.

Measured results

Every number is reproducible from the committed code — N = 100, K = 20, seeded.

hard-guardrail breaches, guaranteed by design

1.0000

approximation ratio vs certified optimum

1,735

routed 2-qubit gates vs the penalty method's 24,530

breaches even under ±20% return-forecast error

The allocation copilot

An interactive Streamlit dashboard — shown here on 41 real multi-asset ETFs. (This page is a static showcase; the live app runs from the GitHub repo.)

Allocation tab: weights, metrics, investor-goal controls — **Allocation.** Final book on real ETFs — zero breaches, holdings pinned at the position cap and floor, four investor-goal sliders.

ADMM convergence residual charts — **ADMM convergence.** Recorded primal/dual residual trajectories and the adaptive-ρ trace — the classical/quantum handshake, plotted as evidence.

Heavy-hex transpilation audit table and chart — **Hardware audit.** Real transpiler runs onto a heavy-hex lattice — OMEGA's largest circuit vs the penalty method's monolithic one.

This is a simulator-based research demo (statevector / tensor-network), not real-QPU execution. At these cluster sizes classical enumeration is exact and the quantum layer matches it — the contribution is the architecture and the compliance guarantee.