quantrs2_device/qec/
implementations.rs

1//! Quantum Error Correction Code Implementations
2//!
3//! This module provides implementations of various quantum error correction codes:
4//! - **Steane Code**: [[7,1,3]] CSS code that can correct any single qubit error
5//! - **Shor Code**: [[9,1,3]] code that protects against both bit and phase flips
6//! - **Surface Code**: Topological code with planar lattice geometry
7//! - **Toric Code**: Topological code defined on a toroidal lattice
8
9use quantrs2_core::qubit::QubitId;
10use scirs2_core::ndarray::Array1;
11use scirs2_core::Complex64;
12
13use super::{
14    LogicalOperator, LogicalOperatorType, PauliOperator, QECResult, QuantumErrorCode,
15    StabilizerGroup, StabilizerType,
16};
17
18/// Steane \[\[7,1,3\]\] quantum error correction code
19///
20/// The Steane code is a CSS (Calderbank-Shor-Steane) code that encodes
21/// one logical qubit into seven physical qubits and can correct any single
22/// qubit error (X, Y, or Z).
23pub struct SteaneCode;
24
25impl SteaneCode {
26    pub const fn new() -> Self {
27        Self
28    }
29}
30
31impl Default for SteaneCode {
32    fn default() -> Self {
33        Self::new()
34    }
35}
36
37impl QuantumErrorCode for SteaneCode {
38    fn get_stabilizers(&self) -> Vec<StabilizerGroup> {
39        /// Number of data qubits in the Steane `[[7,1,3]]` code.
40        const DATA_QUBITS: usize = 7;
41        /// Parity checks of the classical `[7,4,3]` Hamming code that Steane is built from.
42        ///
43        /// Check `k` covers the qubits whose 1-based index has bit `k` set, so the seven
44        /// single-qubit error syndromes are the seven distinct non-zero 3-bit patterns —
45        /// that distinctness is exactly what makes a single error locatable, and it also
46        /// makes every X/Z support intersection even, as CSS commutation requires.
47        ///
48        /// The previous supports (`{0,1,2,3}`, `{1,2,4,5}`, `{3,4,5,6}`) gave qubits 1 and 2
49        /// — and 4 and 5 — identical syndromes, and `X₁`/`Z₃` overlapped in one qubit, so
50        /// the generators did not even commute.
51        const PARITY_CHECKS: [[usize; 4]; 3] = [[0, 2, 4, 6], [1, 2, 5, 6], [3, 4, 5, 6]];
52
53        let group =
54            |support: &[usize; 4], pauli: &PauliOperator, kind: StabilizerType| StabilizerGroup {
55                operators: (0..DATA_QUBITS)
56                    .map(|qubit| {
57                        if support.contains(&qubit) {
58                            pauli.clone()
59                        } else {
60                            PauliOperator::I
61                        }
62                    })
63                    .collect(),
64                qubits: (0..DATA_QUBITS)
65                    .map(|qubit| QubitId::new(qubit as u32))
66                    .collect(),
67                stabilizer_type: kind,
68                weight: support.len(),
69            };
70
71        PARITY_CHECKS
72            .iter()
73            .map(|support| group(support, &PauliOperator::X, StabilizerType::XStabilizer))
74            .chain(
75                PARITY_CHECKS
76                    .iter()
77                    .map(|support| group(support, &PauliOperator::Z, StabilizerType::ZStabilizer)),
78            )
79            .collect()
80    }
81
82    fn get_logical_operators(&self) -> Vec<LogicalOperator> {
83        vec![
84            // Logical X operator (acts on all 7 qubits)
85            LogicalOperator {
86                operators: vec![
87                    PauliOperator::X,
88                    PauliOperator::X,
89                    PauliOperator::X,
90                    PauliOperator::X,
91                    PauliOperator::X,
92                    PauliOperator::X,
93                    PauliOperator::X,
94                ],
95                operator_type: LogicalOperatorType::LogicalX,
96            },
97            // Logical Z operator (acts on all 7 qubits)
98            LogicalOperator {
99                operators: vec![
100                    PauliOperator::Z,
101                    PauliOperator::Z,
102                    PauliOperator::Z,
103                    PauliOperator::Z,
104                    PauliOperator::Z,
105                    PauliOperator::Z,
106                    PauliOperator::Z,
107                ],
108                operator_type: LogicalOperatorType::LogicalZ,
109            },
110        ]
111    }
112
113    fn distance(&self) -> usize {
114        3
115    }
116
117    fn num_data_qubits(&self) -> usize {
118        7
119    }
120
121    fn num_ancilla_qubits(&self) -> usize {
122        6
123    }
124
125    fn logical_qubit_count(&self) -> usize {
126        1
127    }
128
129    fn encode_logical_state(
130        &self,
131        logical_state: &Array1<Complex64>,
132    ) -> QECResult<Array1<Complex64>> {
133        Ok(logical_state.clone())
134    }
135}
136
137/// Shor \[\[9,1,3\]\] quantum error correction code
138///
139/// The Shor code protects one logical qubit using nine physical qubits
140/// and can correct any single qubit error. It combines both bit-flip
141/// and phase-flip protection.
142pub struct ShorCode;
143
144impl ShorCode {
145    pub const fn new() -> Self {
146        Self
147    }
148}
149
150impl Default for ShorCode {
151    fn default() -> Self {
152        Self::new()
153    }
154}
155
156impl QuantumErrorCode for ShorCode {
157    fn get_stabilizers(&self) -> Vec<StabilizerGroup> {
158        vec![
159            // Z-stabilizers for bit-flip correction (6 generators)
160            StabilizerGroup {
161                operators: vec![
162                    PauliOperator::Z,
163                    PauliOperator::Z,
164                    PauliOperator::I,
165                    PauliOperator::I,
166                    PauliOperator::I,
167                    PauliOperator::I,
168                    PauliOperator::I,
169                    PauliOperator::I,
170                    PauliOperator::I,
171                ],
172                qubits: vec![
173                    QubitId::new(0),
174                    QubitId::new(1),
175                    QubitId::new(2),
176                    QubitId::new(3),
177                    QubitId::new(4),
178                    QubitId::new(5),
179                    QubitId::new(6),
180                    QubitId::new(7),
181                    QubitId::new(8),
182                ],
183                stabilizer_type: StabilizerType::ZStabilizer,
184                weight: 2,
185            },
186            StabilizerGroup {
187                operators: vec![
188                    PauliOperator::I,
189                    PauliOperator::Z,
190                    PauliOperator::Z,
191                    PauliOperator::I,
192                    PauliOperator::I,
193                    PauliOperator::I,
194                    PauliOperator::I,
195                    PauliOperator::I,
196                    PauliOperator::I,
197                ],
198                qubits: vec![
199                    QubitId::new(0),
200                    QubitId::new(1),
201                    QubitId::new(2),
202                    QubitId::new(3),
203                    QubitId::new(4),
204                    QubitId::new(5),
205                    QubitId::new(6),
206                    QubitId::new(7),
207                    QubitId::new(8),
208                ],
209                stabilizer_type: StabilizerType::ZStabilizer,
210                weight: 2,
211            },
212            StabilizerGroup {
213                operators: vec![
214                    PauliOperator::I,
215                    PauliOperator::I,
216                    PauliOperator::I,
217                    PauliOperator::Z,
218                    PauliOperator::Z,
219                    PauliOperator::I,
220                    PauliOperator::I,
221                    PauliOperator::I,
222                    PauliOperator::I,
223                ],
224                qubits: vec![
225                    QubitId::new(0),
226                    QubitId::new(1),
227                    QubitId::new(2),
228                    QubitId::new(3),
229                    QubitId::new(4),
230                    QubitId::new(5),
231                    QubitId::new(6),
232                    QubitId::new(7),
233                    QubitId::new(8),
234                ],
235                stabilizer_type: StabilizerType::ZStabilizer,
236                weight: 2,
237            },
238            StabilizerGroup {
239                operators: vec![
240                    PauliOperator::I,
241                    PauliOperator::I,
242                    PauliOperator::I,
243                    PauliOperator::I,
244                    PauliOperator::Z,
245                    PauliOperator::Z,
246                    PauliOperator::I,
247                    PauliOperator::I,
248                    PauliOperator::I,
249                ],
250                qubits: vec![
251                    QubitId::new(0),
252                    QubitId::new(1),
253                    QubitId::new(2),
254                    QubitId::new(3),
255                    QubitId::new(4),
256                    QubitId::new(5),
257                    QubitId::new(6),
258                    QubitId::new(7),
259                    QubitId::new(8),
260                ],
261                stabilizer_type: StabilizerType::ZStabilizer,
262                weight: 2,
263            },
264            StabilizerGroup {
265                operators: vec![
266                    PauliOperator::I,
267                    PauliOperator::I,
268                    PauliOperator::I,
269                    PauliOperator::I,
270                    PauliOperator::I,
271                    PauliOperator::I,
272                    PauliOperator::Z,
273                    PauliOperator::Z,
274                    PauliOperator::I,
275                ],
276                qubits: vec![
277                    QubitId::new(0),
278                    QubitId::new(1),
279                    QubitId::new(2),
280                    QubitId::new(3),
281                    QubitId::new(4),
282                    QubitId::new(5),
283                    QubitId::new(6),
284                    QubitId::new(7),
285                    QubitId::new(8),
286                ],
287                stabilizer_type: StabilizerType::ZStabilizer,
288                weight: 2,
289            },
290            StabilizerGroup {
291                operators: vec![
292                    PauliOperator::I,
293                    PauliOperator::I,
294                    PauliOperator::I,
295                    PauliOperator::I,
296                    PauliOperator::I,
297                    PauliOperator::I,
298                    PauliOperator::I,
299                    PauliOperator::Z,
300                    PauliOperator::Z,
301                ],
302                qubits: vec![
303                    QubitId::new(0),
304                    QubitId::new(1),
305                    QubitId::new(2),
306                    QubitId::new(3),
307                    QubitId::new(4),
308                    QubitId::new(5),
309                    QubitId::new(6),
310                    QubitId::new(7),
311                    QubitId::new(8),
312                ],
313                stabilizer_type: StabilizerType::ZStabilizer,
314                weight: 2,
315            },
316            // X-stabilizers for phase-flip correction (2 generators)
317            StabilizerGroup {
318                operators: vec![
319                    PauliOperator::X,
320                    PauliOperator::X,
321                    PauliOperator::X,
322                    PauliOperator::X,
323                    PauliOperator::X,
324                    PauliOperator::X,
325                    PauliOperator::I,
326                    PauliOperator::I,
327                    PauliOperator::I,
328                ],
329                qubits: vec![
330                    QubitId::new(0),
331                    QubitId::new(1),
332                    QubitId::new(2),
333                    QubitId::new(3),
334                    QubitId::new(4),
335                    QubitId::new(5),
336                    QubitId::new(6),
337                    QubitId::new(7),
338                    QubitId::new(8),
339                ],
340                stabilizer_type: StabilizerType::XStabilizer,
341                weight: 6,
342            },
343            StabilizerGroup {
344                operators: vec![
345                    PauliOperator::I,
346                    PauliOperator::I,
347                    PauliOperator::I,
348                    PauliOperator::X,
349                    PauliOperator::X,
350                    PauliOperator::X,
351                    PauliOperator::X,
352                    PauliOperator::X,
353                    PauliOperator::X,
354                ],
355                qubits: vec![
356                    QubitId::new(0),
357                    QubitId::new(1),
358                    QubitId::new(2),
359                    QubitId::new(3),
360                    QubitId::new(4),
361                    QubitId::new(5),
362                    QubitId::new(6),
363                    QubitId::new(7),
364                    QubitId::new(8),
365                ],
366                stabilizer_type: StabilizerType::XStabilizer,
367                weight: 6,
368            },
369        ]
370    }
371
372    fn get_logical_operators(&self) -> Vec<LogicalOperator> {
373        vec![
374            // Logical X operator (one qubit from each group)
375            LogicalOperator {
376                operators: vec![
377                    PauliOperator::X,
378                    PauliOperator::I,
379                    PauliOperator::I,
380                    PauliOperator::X,
381                    PauliOperator::I,
382                    PauliOperator::I,
383                    PauliOperator::X,
384                    PauliOperator::I,
385                    PauliOperator::I,
386                ],
387                operator_type: LogicalOperatorType::LogicalX,
388            },
389            // Logical Z operator (all qubits)
390            LogicalOperator {
391                operators: vec![
392                    PauliOperator::Z,
393                    PauliOperator::Z,
394                    PauliOperator::Z,
395                    PauliOperator::Z,
396                    PauliOperator::Z,
397                    PauliOperator::Z,
398                    PauliOperator::Z,
399                    PauliOperator::Z,
400                    PauliOperator::Z,
401                ],
402                operator_type: LogicalOperatorType::LogicalZ,
403            },
404        ]
405    }
406
407    fn distance(&self) -> usize {
408        3
409    }
410
411    fn num_data_qubits(&self) -> usize {
412        9
413    }
414
415    fn num_ancilla_qubits(&self) -> usize {
416        8
417    }
418
419    fn logical_qubit_count(&self) -> usize {
420        1
421    }
422
423    fn encode_logical_state(
424        &self,
425        logical_state: &Array1<Complex64>,
426    ) -> QECResult<Array1<Complex64>> {
427        Ok(logical_state.clone())
428    }
429}
430
431/// Surface code with parameterized distance
432///
433/// The surface code is a topological quantum error correction code
434/// defined on a 2D planar lattice. The code distance determines the
435/// number of errors that can be corrected.
436pub struct SurfaceCode {
437    distance: usize,
438}
439
440impl SurfaceCode {
441    pub const fn new(distance: usize) -> Self {
442        Self { distance }
443    }
444}
445
446impl QuantumErrorCode for SurfaceCode {
447    fn get_stabilizers(&self) -> Vec<StabilizerGroup> {
448        // For simplicity, implement stabilizers for distance-3 surface code
449        // This is a basic implementation - full surface codes require more complex lattice handling
450        if self.distance != 3 {
451            // Return a minimal set for other distances - could be extended
452            return vec![
453                StabilizerGroup {
454                    operators: vec![PauliOperator::X, PauliOperator::X],
455                    qubits: vec![QubitId::new(0), QubitId::new(1)],
456                    stabilizer_type: StabilizerType::XStabilizer,
457                    weight: 2,
458                },
459                StabilizerGroup {
460                    operators: vec![PauliOperator::Z, PauliOperator::Z],
461                    qubits: vec![QubitId::new(0), QubitId::new(1)],
462                    stabilizer_type: StabilizerType::ZStabilizer,
463                    weight: 2,
464                },
465            ];
466        }
467
468        // Distance-3 surface code stabilizers (simplified square lattice)
469        // Data qubits: 0-8 arranged as:
470        // 0 1 2
471        // 3 4 5
472        // 6 7 8
473        vec![
474            // X-stabilizers (vertex type)
475            StabilizerGroup {
476                operators: vec![
477                    PauliOperator::X,
478                    PauliOperator::X,
479                    PauliOperator::I,
480                    PauliOperator::X,
481                    PauliOperator::X,
482                    PauliOperator::I,
483                    PauliOperator::I,
484                    PauliOperator::I,
485                    PauliOperator::I,
486                ],
487                qubits: vec![
488                    QubitId::new(0),
489                    QubitId::new(1),
490                    QubitId::new(2),
491                    QubitId::new(3),
492                    QubitId::new(4),
493                    QubitId::new(5),
494                    QubitId::new(6),
495                    QubitId::new(7),
496                    QubitId::new(8),
497                ],
498                stabilizer_type: StabilizerType::XStabilizer,
499                weight: 4,
500            },
501            StabilizerGroup {
502                operators: vec![
503                    PauliOperator::I,
504                    PauliOperator::X,
505                    PauliOperator::X,
506                    PauliOperator::I,
507                    PauliOperator::X,
508                    PauliOperator::X,
509                    PauliOperator::I,
510                    PauliOperator::I,
511                    PauliOperator::I,
512                ],
513                qubits: vec![
514                    QubitId::new(0),
515                    QubitId::new(1),
516                    QubitId::new(2),
517                    QubitId::new(3),
518                    QubitId::new(4),
519                    QubitId::new(5),
520                    QubitId::new(6),
521                    QubitId::new(7),
522                    QubitId::new(8),
523                ],
524                stabilizer_type: StabilizerType::XStabilizer,
525                weight: 4,
526            },
527            StabilizerGroup {
528                operators: vec![
529                    PauliOperator::I,
530                    PauliOperator::I,
531                    PauliOperator::I,
532                    PauliOperator::X,
533                    PauliOperator::X,
534                    PauliOperator::I,
535                    PauliOperator::X,
536                    PauliOperator::X,
537                    PauliOperator::I,
538                ],
539                qubits: vec![
540                    QubitId::new(0),
541                    QubitId::new(1),
542                    QubitId::new(2),
543                    QubitId::new(3),
544                    QubitId::new(4),
545                    QubitId::new(5),
546                    QubitId::new(6),
547                    QubitId::new(7),
548                    QubitId::new(8),
549                ],
550                stabilizer_type: StabilizerType::XStabilizer,
551                weight: 4,
552            },
553            StabilizerGroup {
554                operators: vec![
555                    PauliOperator::I,
556                    PauliOperator::I,
557                    PauliOperator::I,
558                    PauliOperator::I,
559                    PauliOperator::X,
560                    PauliOperator::X,
561                    PauliOperator::I,
562                    PauliOperator::X,
563                    PauliOperator::X,
564                ],
565                qubits: vec![
566                    QubitId::new(0),
567                    QubitId::new(1),
568                    QubitId::new(2),
569                    QubitId::new(3),
570                    QubitId::new(4),
571                    QubitId::new(5),
572                    QubitId::new(6),
573                    QubitId::new(7),
574                    QubitId::new(8),
575                ],
576                stabilizer_type: StabilizerType::XStabilizer,
577                weight: 4,
578            },
579            // Z-stabilizers (plaquette type)
580            StabilizerGroup {
581                operators: vec![
582                    PauliOperator::Z,
583                    PauliOperator::Z,
584                    PauliOperator::I,
585                    PauliOperator::Z,
586                    PauliOperator::Z,
587                    PauliOperator::I,
588                    PauliOperator::I,
589                    PauliOperator::I,
590                    PauliOperator::I,
591                ],
592                qubits: vec![
593                    QubitId::new(0),
594                    QubitId::new(1),
595                    QubitId::new(2),
596                    QubitId::new(3),
597                    QubitId::new(4),
598                    QubitId::new(5),
599                    QubitId::new(6),
600                    QubitId::new(7),
601                    QubitId::new(8),
602                ],
603                stabilizer_type: StabilizerType::ZStabilizer,
604                weight: 4,
605            },
606            StabilizerGroup {
607                operators: vec![
608                    PauliOperator::I,
609                    PauliOperator::Z,
610                    PauliOperator::Z,
611                    PauliOperator::I,
612                    PauliOperator::Z,
613                    PauliOperator::Z,
614                    PauliOperator::I,
615                    PauliOperator::I,
616                    PauliOperator::I,
617                ],
618                qubits: vec![
619                    QubitId::new(0),
620                    QubitId::new(1),
621                    QubitId::new(2),
622                    QubitId::new(3),
623                    QubitId::new(4),
624                    QubitId::new(5),
625                    QubitId::new(6),
626                    QubitId::new(7),
627                    QubitId::new(8),
628                ],
629                stabilizer_type: StabilizerType::ZStabilizer,
630                weight: 4,
631            },
632            StabilizerGroup {
633                operators: vec![
634                    PauliOperator::I,
635                    PauliOperator::I,
636                    PauliOperator::I,
637                    PauliOperator::Z,
638                    PauliOperator::Z,
639                    PauliOperator::I,
640                    PauliOperator::Z,
641                    PauliOperator::Z,
642                    PauliOperator::I,
643                ],
644                qubits: vec![
645                    QubitId::new(0),
646                    QubitId::new(1),
647                    QubitId::new(2),
648                    QubitId::new(3),
649                    QubitId::new(4),
650                    QubitId::new(5),
651                    QubitId::new(6),
652                    QubitId::new(7),
653                    QubitId::new(8),
654                ],
655                stabilizer_type: StabilizerType::ZStabilizer,
656                weight: 4,
657            },
658            StabilizerGroup {
659                operators: vec![
660                    PauliOperator::I,
661                    PauliOperator::I,
662                    PauliOperator::I,
663                    PauliOperator::I,
664                    PauliOperator::Z,
665                    PauliOperator::Z,
666                    PauliOperator::I,
667                    PauliOperator::Z,
668                    PauliOperator::Z,
669                ],
670                qubits: vec![
671                    QubitId::new(0),
672                    QubitId::new(1),
673                    QubitId::new(2),
674                    QubitId::new(3),
675                    QubitId::new(4),
676                    QubitId::new(5),
677                    QubitId::new(6),
678                    QubitId::new(7),
679                    QubitId::new(8),
680                ],
681                stabilizer_type: StabilizerType::ZStabilizer,
682                weight: 4,
683            },
684        ]
685    }
686
687    fn get_logical_operators(&self) -> Vec<LogicalOperator> {
688        if self.distance != 3 {
689            // Basic logical operators for other distances
690            return vec![
691                LogicalOperator {
692                    operators: vec![PauliOperator::X, PauliOperator::I],
693                    operator_type: LogicalOperatorType::LogicalX,
694                },
695                LogicalOperator {
696                    operators: vec![PauliOperator::Z, PauliOperator::I],
697                    operator_type: LogicalOperatorType::LogicalZ,
698                },
699            ];
700        }
701
702        // Distance-3 surface code logical operators
703        vec![
704            // Logical X operator (horizontal string)
705            LogicalOperator {
706                operators: vec![
707                    PauliOperator::X,
708                    PauliOperator::I,
709                    PauliOperator::X,
710                    PauliOperator::I,
711                    PauliOperator::I,
712                    PauliOperator::I,
713                    PauliOperator::X,
714                    PauliOperator::I,
715                    PauliOperator::X,
716                ],
717                operator_type: LogicalOperatorType::LogicalX,
718            },
719            // Logical Z operator (vertical string)
720            LogicalOperator {
721                operators: vec![
722                    PauliOperator::Z,
723                    PauliOperator::Z,
724                    PauliOperator::Z,
725                    PauliOperator::I,
726                    PauliOperator::I,
727                    PauliOperator::I,
728                    PauliOperator::I,
729                    PauliOperator::I,
730                    PauliOperator::I,
731                ],
732                operator_type: LogicalOperatorType::LogicalZ,
733            },
734        ]
735    }
736
737    fn distance(&self) -> usize {
738        self.distance
739    }
740
741    fn num_data_qubits(&self) -> usize {
742        self.distance * self.distance
743    }
744
745    fn num_ancilla_qubits(&self) -> usize {
746        self.distance * self.distance - 1
747    }
748
749    fn logical_qubit_count(&self) -> usize {
750        1
751    }
752
753    fn encode_logical_state(
754        &self,
755        logical_state: &Array1<Complex64>,
756    ) -> QECResult<Array1<Complex64>> {
757        Ok(logical_state.clone())
758    }
759}
760
761/// Toric code with parameterized lattice dimensions
762///
763/// The toric code is a topological quantum error correction code
764/// defined on a torus (periodic boundary conditions in both directions).
765/// It encodes two logical qubits.
766pub struct ToricCode {
767    dimensions: (usize, usize),
768}
769
770impl ToricCode {
771    pub const fn new(dimensions: (usize, usize)) -> Self {
772        Self { dimensions }
773    }
774}
775
776impl QuantumErrorCode for ToricCode {
777    fn get_stabilizers(&self) -> Vec<StabilizerGroup> {
778        // Implement a basic 2x2 toric code for simplicity
779        // For general dimensions, this would need more complex lattice handling
780        if self.dimensions != (2, 2) {
781            // Return minimal stabilizers for other dimensions
782            return vec![
783                StabilizerGroup {
784                    operators: vec![PauliOperator::X, PauliOperator::X],
785                    qubits: vec![QubitId::new(0), QubitId::new(1)],
786                    stabilizer_type: StabilizerType::XStabilizer,
787                    weight: 2,
788                },
789                StabilizerGroup {
790                    operators: vec![PauliOperator::Z, PauliOperator::Z],
791                    qubits: vec![QubitId::new(0), QubitId::new(1)],
792                    stabilizer_type: StabilizerType::ZStabilizer,
793                    weight: 2,
794                },
795            ];
796        }
797
798        // 2x2 toric code has 8 data qubits arranged on a torus
799        // X-stabilizers (vertex type) and Z-stabilizers (plaquette type)
800        vec![
801            // X-stabilizers (vertex type) - 4 stabilizers for 2x2 torus
802            StabilizerGroup {
803                operators: vec![
804                    PauliOperator::X,
805                    PauliOperator::X,
806                    PauliOperator::I,
807                    PauliOperator::I,
808                    PauliOperator::X,
809                    PauliOperator::X,
810                    PauliOperator::I,
811                    PauliOperator::I,
812                ],
813                qubits: vec![
814                    QubitId::new(0),
815                    QubitId::new(1),
816                    QubitId::new(2),
817                    QubitId::new(3),
818                    QubitId::new(4),
819                    QubitId::new(5),
820                    QubitId::new(6),
821                    QubitId::new(7),
822                ],
823                stabilizer_type: StabilizerType::XStabilizer,
824                weight: 4,
825            },
826            StabilizerGroup {
827                operators: vec![
828                    PauliOperator::I,
829                    PauliOperator::I,
830                    PauliOperator::X,
831                    PauliOperator::X,
832                    PauliOperator::I,
833                    PauliOperator::I,
834                    PauliOperator::X,
835                    PauliOperator::X,
836                ],
837                qubits: vec![
838                    QubitId::new(0),
839                    QubitId::new(1),
840                    QubitId::new(2),
841                    QubitId::new(3),
842                    QubitId::new(4),
843                    QubitId::new(5),
844                    QubitId::new(6),
845                    QubitId::new(7),
846                ],
847                stabilizer_type: StabilizerType::XStabilizer,
848                weight: 4,
849            },
850            StabilizerGroup {
851                operators: vec![
852                    PauliOperator::I,
853                    PauliOperator::I,
854                    PauliOperator::I,
855                    PauliOperator::I,
856                    PauliOperator::X,
857                    PauliOperator::X,
858                    PauliOperator::I,
859                    PauliOperator::I,
860                ],
861                qubits: vec![
862                    QubitId::new(0),
863                    QubitId::new(1),
864                    QubitId::new(2),
865                    QubitId::new(3),
866                    QubitId::new(4),
867                    QubitId::new(5),
868                    QubitId::new(6),
869                    QubitId::new(7),
870                ],
871                stabilizer_type: StabilizerType::XStabilizer,
872                weight: 4,
873            },
874            StabilizerGroup {
875                operators: vec![
876                    PauliOperator::I,
877                    PauliOperator::I,
878                    PauliOperator::I,
879                    PauliOperator::I,
880                    PauliOperator::I,
881                    PauliOperator::I,
882                    PauliOperator::X,
883                    PauliOperator::X,
884                ],
885                qubits: vec![
886                    QubitId::new(0),
887                    QubitId::new(1),
888                    QubitId::new(2),
889                    QubitId::new(3),
890                    QubitId::new(4),
891                    QubitId::new(5),
892                    QubitId::new(6),
893                    QubitId::new(7),
894                ],
895                stabilizer_type: StabilizerType::XStabilizer,
896                weight: 4,
897            },
898            // Z-stabilizers (plaquette type) - 4 stabilizers for 2x2 torus
899            StabilizerGroup {
900                operators: vec![
901                    PauliOperator::Z,
902                    PauliOperator::Z,
903                    PauliOperator::I,
904                    PauliOperator::I,
905                    PauliOperator::Z,
906                    PauliOperator::Z,
907                    PauliOperator::I,
908                    PauliOperator::I,
909                ],
910                qubits: vec![
911                    QubitId::new(0),
912                    QubitId::new(1),
913                    QubitId::new(2),
914                    QubitId::new(3),
915                    QubitId::new(4),
916                    QubitId::new(5),
917                    QubitId::new(6),
918                    QubitId::new(7),
919                ],
920                stabilizer_type: StabilizerType::ZStabilizer,
921                weight: 4,
922            },
923            StabilizerGroup {
924                operators: vec![
925                    PauliOperator::I,
926                    PauliOperator::I,
927                    PauliOperator::Z,
928                    PauliOperator::Z,
929                    PauliOperator::I,
930                    PauliOperator::I,
931                    PauliOperator::Z,
932                    PauliOperator::Z,
933                ],
934                qubits: vec![
935                    QubitId::new(0),
936                    QubitId::new(1),
937                    QubitId::new(2),
938                    QubitId::new(3),
939                    QubitId::new(4),
940                    QubitId::new(5),
941                    QubitId::new(6),
942                    QubitId::new(7),
943                ],
944                stabilizer_type: StabilizerType::ZStabilizer,
945                weight: 4,
946            },
947            StabilizerGroup {
948                operators: vec![
949                    PauliOperator::I,
950                    PauliOperator::I,
951                    PauliOperator::I,
952                    PauliOperator::I,
953                    PauliOperator::Z,
954                    PauliOperator::Z,
955                    PauliOperator::I,
956                    PauliOperator::I,
957                ],
958                qubits: vec![
959                    QubitId::new(0),
960                    QubitId::new(1),
961                    QubitId::new(2),
962                    QubitId::new(3),
963                    QubitId::new(4),
964                    QubitId::new(5),
965                    QubitId::new(6),
966                    QubitId::new(7),
967                ],
968                stabilizer_type: StabilizerType::ZStabilizer,
969                weight: 4,
970            },
971            StabilizerGroup {
972                operators: vec![
973                    PauliOperator::I,
974                    PauliOperator::I,
975                    PauliOperator::I,
976                    PauliOperator::I,
977                    PauliOperator::I,
978                    PauliOperator::I,
979                    PauliOperator::Z,
980                    PauliOperator::Z,
981                ],
982                qubits: vec![
983                    QubitId::new(0),
984                    QubitId::new(1),
985                    QubitId::new(2),
986                    QubitId::new(3),
987                    QubitId::new(4),
988                    QubitId::new(5),
989                    QubitId::new(6),
990                    QubitId::new(7),
991                ],
992                stabilizer_type: StabilizerType::ZStabilizer,
993                weight: 4,
994            },
995        ]
996    }
997
998    fn get_logical_operators(&self) -> Vec<LogicalOperator> {
999        if self.dimensions != (2, 2) {
1000            // Basic logical operators for other dimensions
1001            return vec![
1002                LogicalOperator {
1003                    operators: vec![PauliOperator::X, PauliOperator::I],
1004                    operator_type: LogicalOperatorType::LogicalX,
1005                },
1006                LogicalOperator {
1007                    operators: vec![PauliOperator::Z, PauliOperator::I],
1008                    operator_type: LogicalOperatorType::LogicalZ,
1009                },
1010            ];
1011        }
1012
1013        // 2x2 toric code logical operators (2 logical qubits due to torus topology)
1014        vec![
1015            // First logical X operator (horizontal winding)
1016            LogicalOperator {
1017                operators: vec![
1018                    PauliOperator::X,
1019                    PauliOperator::I,
1020                    PauliOperator::X,
1021                    PauliOperator::I,
1022                    PauliOperator::I,
1023                    PauliOperator::I,
1024                    PauliOperator::I,
1025                    PauliOperator::I,
1026                ],
1027                operator_type: LogicalOperatorType::LogicalX,
1028            },
1029            // First logical Z operator (vertical winding)
1030            LogicalOperator {
1031                operators: vec![
1032                    PauliOperator::Z,
1033                    PauliOperator::I,
1034                    PauliOperator::I,
1035                    PauliOperator::I,
1036                    PauliOperator::Z,
1037                    PauliOperator::I,
1038                    PauliOperator::I,
1039                    PauliOperator::I,
1040                ],
1041                operator_type: LogicalOperatorType::LogicalZ,
1042            },
1043        ]
1044    }
1045
1046    fn distance(&self) -> usize {
1047        self.dimensions.0.min(self.dimensions.1)
1048    }
1049
1050    fn num_data_qubits(&self) -> usize {
1051        2 * self.dimensions.0 * self.dimensions.1
1052    }
1053
1054    fn num_ancilla_qubits(&self) -> usize {
1055        self.dimensions.0 * self.dimensions.1
1056    }
1057
1058    fn logical_qubit_count(&self) -> usize {
1059        2
1060    }
1061
1062    fn encode_logical_state(
1063        &self,
1064        logical_state: &Array1<Complex64>,
1065    ) -> QECResult<Array1<Complex64>> {
1066        Ok(logical_state.clone())
1067    }
1068}
quantrs2_device/qec/implementations.rs

quantrs2_device/qec/
implementations.rs
