Coverage for /home/runner/work/tket/tket/pytket/pytket/utils/measurements.py: 100%

1# Copyright Quantinuum 

2# 

3# Licensed under the Apache License, Version 2.0 (the "License"); 

4# you may not use this file except in compliance with the License. 

5# You may obtain a copy of the License at 

6# 

7# http://www.apache.org/licenses/LICENSE-2.0 

8# 

9# Unless required by applicable law or agreed to in writing, software 

10# distributed under the License is distributed on an "AS IS" BASIS, 

11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 

12# See the License for the specific language governing permissions and 

13# limitations under the License. 

14 

15from collections.abc import Iterable 

16 

17from pytket.circuit import Bit, Circuit 

18from pytket.pauli import Pauli, QubitPauliString 

19 

20from .operators import QubitPauliOperator 

21 

22 

23def append_pauli_measurement(pauli_string: QubitPauliString, circ: Circuit) -> None: 

24 """Appends measurement instructions to a given circuit, measuring each qubit in a 

25 given basis. 

26 

27 :param pauli_string: The pauli string to measure 

28 :type pauli_string: QubitPauliString 

29 :param circ: Circuit to add measurement to. 

30 :type circ: Circuit 

31 """ 

32 measured_qbs = [] 

33 for qb, p in pauli_string.map.items(): 

34 if p == Pauli.I: 

35 continue 

36 measured_qbs.append(qb) 

37 if p == Pauli.X: 

38 circ.H(qb) 

39 elif p == Pauli.Y: 

40 circ.Rx(0.5, qb) 

41 for b_idx, qb in enumerate(measured_qbs): 

42 unit = Bit(b_idx) 

43 circ.add_bit(unit, False) 

44 circ.Measure(qb, unit) 

45 

46 

47def _all_pauli_measurements( 

48 operator: QubitPauliOperator, circ: Circuit 

49) -> Iterable[Circuit]: 

50 """For each term in the operator, yields a copy of the given circuit with the 

51 appropriate measurements on each qubit. The trivial term is omitted. 

52 

53 :param operator: The operator 

54 :type operator: QubitPauliOperator 

55 :param circ: The circuit generating the desired state 

56 :type circ: Circuit 

57 :return: List of circuits in order of term from the operator 

58 :rtype: Iterable[Circuit] 

59 """ 

60 for pauli_string in operator._dict.keys(): 

61 if not pauli_string.map: 

62 continue 

63 copy = circ.copy() 

64 append_pauli_measurement(pauli_string, copy) 

65 yield copy