# Physics Quantum

> Model quantum systems (states, operators, measurement, entanglement) and perform calculations using Dirac notation, with checks against limits and known results.

- Skill: `quantumquirkxyz/physics-quantum` (Agent Skill)
- Install (CLI): `npx skillmds@latest add quantumquirkxyz/physics-quantum`
- Raw SKILL.md: https://api.skillmd.com/api/skills/quantumquirkxyz/physics-quantum/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: quantumquirkxyz (https://skillmd.com/u/quantumquirkxyz)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/quantumquirkxyz/physics-quantum

---


## Contract

- **Input:** problem description and inputs defined by the skill body.
- **Output:** Markdown artifact with completed process steps.
- **Side effects:** none.
- **Dependencies:** none.
- **Stop condition:** all process steps executed; artifact saved with required sections.
- **Risk:** low.
- **Boundary:** produces reasoning artifact only; no system changes.


# Quantum Physics Modeling

Construct a **quantum model** of a system — state space, Hamiltonian, measurement — and answer a question about it with explicit regime checks.

## When to use

- The user wants to model a quantum system or compute an observable.
- A claim from quantum information, quantum computing, atomic/molecular physics, or condensed matter needs grounding.
- Another skill (e.g. `cs-cryptography` or quantum-related ML) needs a quantum-mechanical sub-model.

## Process

### 1. Define the system

Specify:

- **Hilbert space** — finite (qubits, spin-1/2) or infinite (position, Fock).
- **Basis** — computational, Fock, position, momentum.
- **State** — pure |ψ⟩ or mixed ρ; for multi-party, identify subsystems.
- **Hamiltonian** — kinetic + potential; cite which interactions are kept.

**Completion criterion:** Hilbert space, basis, state, and Hamiltonian all explicit.

### 2. Identify the regime

Locate the system in the taxonomy:

- Non-relativistic vs relativistic (Schrödinger vs Dirac).
- Single-particle vs many-body.
- Closed vs open (Lindblad master equation if open).
- Discrete (qubit) vs continuous-variable.

Pick the right formalism: Schrödinger picture, Heisenberg, interaction picture, path integral.

**Completion criterion:** regime and formalism chosen with a one-line justification.

### 3. Compute

Solve by the path that matches the system:

- **Exactly solvable** — harmonic oscillator, hydrogen, two-level, Jaynes–Cummings.
- **Perturbation theory** — time-independent or time-dependent; cite the small parameter.
- **Variational** — ansatz + minimize ⟨ψ|H|ψ⟩.
- **Numerical** — exact diagonalisation, DMRG, tensor networks, QMC.

For each step, state approximations and truncations.

**Completion criterion:** method named, approximations listed, computation executed.

### 4. Units and limits check

- **Units:** verify ℏ, c, k_B are set correctly; energies, lengths, times have plausible orders of magnitude.
- **Limits:** check classical limit (ℏ→0), continuum limit, weak-coupling limit, large-N limit.
- **Symmetries:** confirm the answer respects them (rotational, particle-number, parity).

**Completion criterion:** units sanity-checked; at least one limit recovered.

### 5. Deliver

Markdown artifact with: system definition, regime, computation, units/limits, and the answer with an uncertainty or approximation note. Cite the method used.

**Completion criterion:** artifact covers all five; answer is reproducible.