Continuous-time Pauli propagation: real-space adaptive Lindbladian evolution - #181
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This implements the split suggested in #180 (comment) and fixes some issues that surfaced during the split or from copilot findings. Should be merged before #181 cc @AlexSchuckert --------- Co-authored-by: Cursor <cursoragent@cursor.com>
…daptive Lindbladian evolution Direct Heisenberg-picture evolution O ← exp(dt·L*)O on an adaptively truncated Pauli-string basis: exact in dt within the working basis, no Trotter splitting. LindbladSpec precompiles Hermitian-Pauli (fast diagonal) and general complex Pauli-sum jumps (σ±, amplitude damping, precomputed L†L); pc_step does two-hop leakage enrichment + predictor/ corrector matrix-free exponential via quspin-expm (MIT), with the truncation policy in one PcStepConfig (max_basis rank cap, admit_basis displacement bound, drop_tol prune, tau_add admission filter). Python: ppvm.Lindbladian with numpy hot path + string convenience API, mimalloc global allocator (~50% peak-RSS cut on adaptive paths), two jupytext demos, tests against dense-Liouvillian / closed-form / eig references. Split 2/4 of the CTPP work; the momentum-sector (orbit-rep) evolution follows in split 3. Full history: branch continuous-time-pauli-propagation. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…ord) — cargo machete Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
bitvec implements BitStore for u64 only on 64-bit targets, so the [u64; 2] word storage broke the wasm32 workspace build. The chunk type is now target-gated: two u64 chunks on 64-bit targets (bit-identical to before), four u32 chunks elsewhere — 128 qubits either way. The chunk loops (anti_commutes / pauli_mul) were already width-agnostic. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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## Summary - Same kind of cleanup as #193 did for #180: split the 1300-line `ppvm-lindblad` `lib.rs` / `LindbladSpec` impl into `word`, `algebra`, `spec`, `basis`, `step`, and `tests`, keeping the public `ppvm_lindblad::*` API. - Collapses the timed/untimed `pc_step` copy, demotes `ppvm-pauli-sum` to a dev-dependency, drops unused `approx`, strips 182-forward `orbit_rep` doc links, and forwards `admit_basis` / `tau_add` on the Python string `pc_step`. - **Base is #181 (`split/2-ctpp-core`) on purpose.** #193 replaces #180 and is not an ancestor of #181; retargeting this at #193 now would mix the whole CTPP crate into the diff. After #193 merges and #181 is rebased onto it, this PR rebases with #181. ## Test plan - [x] `cargo test -p ppvm-lindblad` (6 passed) - [x] `cargo clippy -p ppvm-lindblad --all-targets -- -D warnings` - [x] `cargo check -p ppvm-python-native` - [ ] Rebase onto #181 after #181 is retargeted onto #193 Made with [Cursor](https://cursor.com) --------- Co-authored-by: Cursor <cursoragent@cursor.com>
**PR 3 of 4** splitting #178 (stacked on #181). Full history: branch [`continuous-time-pauli-propagation`](https://github.com/QuEraComputing/ppvm/tree/continuous-time-pauli-propagation). The two consumers of the translation-symmetry primitive from PR 1: - **Trotter path**: `PauliSum.symmetry_merge` (k = 0) and `PauliSum.momentum_merge` (k ≠ 0, complex operator carried as a *real pair*; character-weighted fold rescaled by |G| to the summing projector, so merging after every gate layer is idempotent). `TranslationGroup`, `canonicalize_basis_arr{,_complex}`, and `check_momentum_sector_arr` exposed via `ppvm._core`. All inputs validated at the FFI boundary (`ValueError`, not panics). - **CTPP path**: `pc_step_orbit_rep` — per-step adaptive evolution entirely in orbit-representative form (complex coefficients, phase-aware action, same cached-CSC expm engine and `PcStepConfig` truncation policy as the real-space step). The live basis is ~|G|× smaller than full-basis evolution, and the reduction persists through every step; observables come out per momentum mode. Tests: momentum-merge correctness incl. k-resolved Trotter convergence vs exact diagonalization; orbit-rep evolution vs full-basis-then-project (exact match); real/complex equivalence at k = 0. Regression gates rerun on this exact tree: L=5 momentum sanity bit-identical to the recorded reference; the τ_add real-space cell reproduces median 5.19e-3 / peak basis 77,820 exactly. 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Co-authored-by: David Plankensteiner <dplankensteiner@quera.com> Co-authored-by: David Plankensteiner <david-pl@users.noreply.github.com>
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PR 2 of 4 splitting #178 (stacked on #180). Full history: branch
continuous-time-pauli-propagation.The core CTPP method: direct Heisenberg-picture evolution
O ← exp(dt·L*) Oof Pauli observables under a Lindbladian, on an adaptively truncated Pauli-string basis. Exact indtwithin the working basis — no Trotter splitting; the only approximation is truncation.ppvm-lindbladcrate:LindbladSpecprecompiles Hermitian-Pauli jumps (fast diagonal path) and general complex Pauli-sum jumps (σ±/amplitude damping via a precomputed L†L expansion).pc_step= two-hop leakage enrichment + predictor/corrector matrix-free exponential (cached-CSC columns fed toquspin-expm, MIT-licensed pin; Al-Mohy–Higham Taylor partition selection with a truncation-matched relaxed table). Truncation policy in onePcStepConfig:max_basisrank cap (primary dial),admit_basisworking-set bound (displacement truncation),drop_tolprune,tau_addadmission filter.ppvm.Lindbladianwith a numpy-array hot path plus string-keyed convenience API;mimallocas the extension's global allocator (~50% peak-RSS reduction on the allocation-heavy adaptive paths); two jupytext demos.pc_steppinned againstnumpy.linalg.eig; O(dt³) per-step scaling of the predictor-corrector.Benchmarks backing the design choices (190× vs Trotter at L=21 matched accuracy; external cross-validation vs Begušić & Chan, PRX Quantum 6, 020302 at L=41): ledgers arrive in PR 4 of the stack.
The translation-symmetric (momentum-sector) variant follows in PR 3.
🤖 Generated with Claude Code