Research · Quantum simulation
Agent evacuation decision
A four-qubit matrix product state (χ = 2) explores correlated shelter-vs-evacuate outcomes under imaginary-time evolution — a compact demo of how Qdit models multi-agent decisions beyond classical surveys.
Simulation parameters
- Qubits / agents
- 4
- MPS bond χ
- 2
- Imaginary time β
- 2
- Trotter steps
- 100
- Local fields h
- [-0.8, -0.3, -0.5, -0.1]
- Coupling J
- 0.6
Uniform prior over all 16 evacuation patterns, evolved under H = −Σ hᵢ Zᵢ − J Σ Zᵢ Zᵢ₊₁ (|0⟩ = shelter, |1⟩ = evacuate). Most likely outcome: 1111 at 92.4% — 4 of 4 agents evacuate.
| Bitstring | Interpretation | P(s) | Weight |
|---|---|---|---|
| 1111peak | Agent 1: Evacuate · Agent 2: Evacuate · Agent 3: Evacuate · Agent 4: Evacuate | 92.42% | |
| 1110 | Agent 1: Evacuate · Agent 2: Evacuate · Agent 3: Evacuate · Agent 4: Shelter | 5.62% | |
| 1100 | Agent 1: Evacuate · Agent 2: Evacuate · Agent 3: Shelter · Agent 4: Shelter | 0.76% | |
| 0111 | Agent 1: Shelter · Agent 2: Evacuate · Agent 3: Evacuate · Agent 4: Evacuate | 0.34% | |
| 1000 | Agent 1: Evacuate · Agent 2: Shelter · Agent 3: Shelter · Agent 4: Shelter | 0.23% | |
| 1011 | Agent 1: Evacuate · Agent 2: Shelter · Agent 3: Evacuate · Agent 4: Evacuate | 0.23% | |
| 0000 | Agent 1: Shelter · Agent 2: Shelter · Agent 3: Shelter · Agent 4: Shelter | 0.10% | |
| 0011 | Agent 1: Shelter · Agent 2: Shelter · Agent 3: Evacuate · Agent 4: Evacuate | 0.10% | |
| 1101 | Agent 1: Evacuate · Agent 2: Evacuate · Agent 3: Shelter · Agent 4: Evacuate | 0.10% | |
| 1001 | Agent 1: Evacuate · Agent 2: Shelter · Agent 3: Shelter · Agent 4: Evacuate | 0.03% | |
| 0110 | Agent 1: Shelter · Agent 2: Evacuate · Agent 3: Evacuate · Agent 4: Shelter | 0.02% | |
| 1010 | Agent 1: Evacuate · Agent 2: Shelter · Agent 3: Evacuate · Agent 4: Shelter | 0.01% | |
| 0001 | Agent 1: Shelter · Agent 2: Shelter · Agent 3: Shelter · Agent 4: Evacuate | 0.01% | |
| 0010 | Agent 1: Shelter · Agent 2: Shelter · Agent 3: Evacuate · Agent 4: Shelter | <0.01% | |
| 0100 | Agent 1: Shelter · Agent 2: Evacuate · Agent 3: Shelter · Agent 4: Shelter | <0.01% | |
| 0101 | Agent 1: Shelter · Agent 2: Evacuate · Agent 3: Shelter · Agent 4: Evacuate | <0.01% |
Classical surveys assume independent agent choices. This quantum Ising model captures peer influence (ZZ coupling) and heterogeneous risk fields (hᵢ), producing correlated evacuation patterns classical factor models miss.