Naive Implementation of the Encoding Circuit (#154)

Co-authored-by: Stefan Krastanov <[email protected]>
Co-authored-by: Anthony Micciche <[email protected]>

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 # News
 
+## v0.8.17 - dev
+- **(fix)** Some `affectedqubits` methods were returning single integers instead of a one-tuple.
+- The non-public `ECC` module has seen a few improvements (a `naive_encoding_circuit` implementation and a few new codes), as well as some breaking changes to API.
+
 ## v0.8.16 - 2023-08-31
 
 - **(breaking)** Changes to the circuit generation in the non-public ECC module. Adding a Shor syndrome measurement circuit.

Project.toml

@@ -1,7 +1,7 @@
 name = "QuantumClifford"
 uuid = "0525e862-1e90-11e9-3e4d-1b39d7109de1"
 authors = ["Stefan Krastanov <[email protected]>"]
-version = "0.8.16"
+version = "0.8.17"
 
 [deps]
 Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"

docs/make.jl

@@ -15,13 +15,13 @@ ENV["COLUMNS"] = 80
 bib = CitationBibliography(joinpath(@__DIR__,"src/references.bib"),style=:authoryear)
 
 makedocs(
-bib,
+plugins = [bib],
 doctest = false,
 clean = true,
 sitename = "QuantumClifford.jl",
-format = Documenter.HTML(),
+format = Documenter.HTML(size_threshold_ignore = ["API.md"]),
 modules = [QuantumClifford, QuantumClifford.Experimental.NoisyCircuits, QuantumInterface],
-strict = Documenter.except(:missing_docs),
+warnonly = [:missing_docs],
 authors = "Stefan Krastanov",
 pages = [
 "QuantumClifford.jl" => "index.md",

docs/src/ecc_example_sim.md

@@ -12,7 +12,7 @@ Consider Steane 7-qubit code:
 
 ```@example 1
 using QuantumClifford
-using QuantumClifford.ECC: Steane7, naive_syndrome_circuit, encoding_circuit, parity_checks, code_s, code_n
+using QuantumClifford.ECC: Steane7, naive_syndrome_circuit, naive_encoding_circuit, parity_checks, code_s, code_n
 using Quantikz
 
 code = Steane7()
@@ -21,7 +21,7 @@ H = parity_checks(code)
 
 ... and the corresponding encoding circuit
 ```@example 1
-ecirc = encoding_circuit(code)
+ecirc = naive_encoding_circuit(code)
 ```
 
 ... and the corresponding syndrome measurement circuit (the non-fault tolerant one)

docs/src/references.bib

@@ -158,12 +158,44 @@ @article{gullans2020dynamical
   publisher={APS}
 }
 
-@misc{hein2006entanglement,
-	title = {Entanglement in Graph States and its Applications},
-	url = {http://arxiv.org/abs/quant-ph/0602096},
-	journaltitle = {arXiv preprint arXiv:quant-ph/0602096},
-	author = {Hein, M. and Dür, W. and Eisert, J. and Raussendorf, R. and Nest, M. Van den and Briegel, H.-J.},
-	year = {2006},
+@article{hein2006entanglement,
+  title={Entanglement in graph states and its applications},
+  author={Hein, Marc and D{\"u}r, Wolfgang and Eisert, Jens and Raussendorf, Robert and Nest, M and Briegel, H-J},
+  journal={arXiv preprint quant-ph/0602096},
+  url={https://arxiv.org/abs/quant-ph/0602096},
+  doi={10.48550/arXiv.quant-ph/0602096},
+  year={2006}
+}
+
+% Encoding circuits
+
+@article{cleve1997efficient,
+  title={Efficient computations of encodings for quantum error correction},
+  author={Cleve, Richard and Gottesman, Daniel},
+  journal={Physical Review A},
+  volume={56},
+  number={1},
+  pages={76},
+  year={1997},
+  publisher={APS}
+}
+
+@inproceedings{grassl2011variations,
+  title={Variations on encoding circuits for stabilizer quantum codes},
+  author={Grassl, Markus},
+  booktitle={International Conference on Coding and Cryptology},
+  pages={142--158},
+  year={2011},
+  organization={Springer}
+}
+
+@article{grassl2002algorithmic,
+  title={Algorithmic aspects of quantum error-correcting codes},
+  author={Grassl, Markus},
+  journal={Mathematics of Quantum Computation},
+  pages={223--252},
+  year={2002},
+  publisher={CRC Press Boca Raton, FL}
 }
 
 % Examples of results that employ the tableaux formalism

src/QuantumClifford.jl

@@ -50,6 +50,7 @@ export
     sHadamard, sPhase, sInvPhase, SingleQubitOperator, sId1, sX, sY, sZ,
     sCNOT, sCPHASE, sSWAP,
     sXCX, sXCY, sXCZ, sYCX, sYCY, sYCZ, sZCX, sZCY, sZCZ,
+    sZCrY,
     # Misc Ops
     SparseGate,
     sMX, sMY, sMZ, PauliMeasurement, Reset, sMRX, sMRY, sMRZ,
@@ -504,6 +505,11 @@ operators are tracked as well.
 When the constructor is called on an incomplete [`Stabilizer`](@ref) it
 automatically calculates the destabilizers and logical operators, following
 chapter 4 of [gottesman1997stabilizer](@cite).
+Under the hood the conversion uses the [`canonicalize_gott!`](@ref) canonicalization.
+That canonicalization permutes the columns of the tableau, but we automatically undo the
+column permutation in the preparation of a `MixedDestabilizer` so that qubits are not reindexed.
+The boolean keyword arguments `undoperm` and `reportperm` can be used to control this behavior
+and to report the permutations explicitly.
 
 See also: [`stabilizerview`](@ref), [`destabilizerview`](@ref), [`logicalxview`](@ref), [`logicalzview`](@ref)
 """
@@ -513,7 +519,7 @@ mutable struct MixedDestabilizer{T<:Tableau} <: AbstractStabilizer
 end
 
 # Added a lot of type assertions to help Julia infer types
-function MixedDestabilizer(stab::Stabilizer{T}; undoperm=true) where {T}
+function MixedDestabilizer(stab::Stabilizer{T}; undoperm=true, reportperm=false) where {T}
     rows,n = size(stab)
     stab, r, s, permx, permz = canonicalize_gott!(copy(stab))
     t = zero(T, n*2, n)
@@ -550,8 +556,13 @@ function MixedDestabilizer(stab::Stabilizer{T}; undoperm=true) where {T}
     end
     if undoperm
         t = t[:,invperm(permx[permz])]::T
+        return MixedDestabilizer(t, r+s)::MixedDestabilizer{T}
+    end
+    if reportperm
+        return (MixedDestabilizer(t, r+s)::MixedDestabilizer{T}, r, permx, permz)
+    else
+        return MixedDestabilizer(t, r+s)::MixedDestabilizer{T}
     end
-    MixedDestabilizer(t, r+s)::MixedDestabilizer{T}
 end
 
 function MixedDestabilizer(d::Destabilizer, r::Int)

src/affectedqubits.jl

@@ -1,8 +1,8 @@
 """A method giving the qubits acted upon by a given operation. Part of the Noise interface."""
 function affectedqubits end
-affectedqubits(g::AbstractSingleQubitOperator) = (g.q)
+affectedqubits(g::AbstractSingleQubitOperator) = (g.q,)
 affectedqubits(g::AbstractTwoQubitOperator) = (g.q1, g.q2)
-affectedqubits(g::NoisyGate) = affectedqubits(g.gate)
+affectedqubits(g::NoisyGate) = affectedqubits(g.gate,)
 affectedqubits(g::SparseGate) = g.indices
 affectedqubits(b::BellMeasurement) = map(m->m.qubit, b.measurements)
 affectedqubits(r::Reset) = r.indices

src/canonicalization.jl

@@ -258,5 +258,6 @@ function _canonicalize_gott!(stabilizer::Stabilizer; phases::Val{B}=Val(true)) w
     end
     zperm, s = gott_standard_form_indices((@view xzs[end÷2+1:end,:]),rows,columns,skip=r)
     permute!(stabilizer,zperm)
+    # we have r+s==rows (or we have trailing rows that are zeroed)
     stabilizer, r, s, xperm, zperm
 end