gQ*dZddlmZddlZddlmZmZmZddl m Z ddl m Z Gdd e Z Gd d eZdS) zMDefine a Quantum Fourier Transform circuit (QFT) and a native gate (QFTGate).) annotationsN)QuantumRegisterCircuitInstructionGate)deprecate_func)BlueprintCircuitcneZdZdZeddd d%d&fd Zed'fd Zejd(dZed'dZ e jd)dZ ed*dZ e jd+dZ ed*dZ e jd,dZ d*dZ d-d.d!Z d/d0d#Zd1fd$ ZxZS)2QFTa! Quantum Fourier Transform Circuit. The Quantum Fourier Transform (QFT) on :math:`n` qubits is the operation .. math:: |j\rangle \mapsto \frac{1}{2^{n/2}} \sum_{k=0}^{2^n - 1} e^{2\pi ijk / 2^n} |k\rangle The circuit that implements this transformation can be implemented using Hadamard gates on each qubit, a series of controlled-U1 (or Z, depending on the phase) gates and a layer of Swap gates. The layer of Swap gates can in principle be dropped if the QFT appears at the end of the circuit, since then the re-ordering can be done classically. They can be turned off using the ``do_swaps`` attribute. For 4 qubits, the circuit that implements this transformation is: .. plot:: :alt: Diagram illustrating the previously described circuit. from qiskit.circuit.library import QFT from qiskit.visualization.library import _generate_circuit_library_visualization circuit = QFT(4) _generate_circuit_library_visualization(circuit) The inverse QFT can be obtained by calling the ``inverse`` method on this class. The respective circuit diagram is: .. plot:: :alt: Diagram illustrating the previously described circuit. from qiskit.circuit.library import QFT from qiskit.visualization.library import _generate_circuit_library_visualization circuit = QFT(4).inverse() _generate_circuit_library_visualization(circuit) One method to reduce circuit depth is to implement the QFT approximately by ignoring controlled-phase rotations where the angle is beneath a threshold. This is discussed in more detail in https://arxiv.org/abs/quant-ph/9601018 or https://arxiv.org/abs/quant-ph/0403071. Here, this can be adjusted using the ``approximation_degree`` attribute: the smallest ``approximation_degree`` rotation angles are dropped from the QFT. For instance, a QFT on 5 qubits with approximation degree 2 yields (the barriers are dropped in this example): .. plot:: :alt: Diagram illustrating the previously described circuit. from qiskit.circuit.library import QFT from qiskit.visualization.library import _generate_circuit_library_visualization circuit = QFT(5, approximation_degree=2) _generate_circuit_library_visualization(circuit) z1.3)zxUse qiskit.circuit.library.QFTGate or qiskit.synthesis.qft.synth_qft_full instead, for access to all previous arguments.T)sinceadditional_msgpendingNrF num_qubits int | Noneapproximation_degreeintdo_swapsboolinverseinsert_barriersname str | NonereturnNonec||rdnd}t|||_||_||_||_||_dS)aConstruct a new QFT circuit. Args: num_qubits: The number of qubits on which the QFT acts. approximation_degree: The degree of approximation (0 for no approximation). do_swaps: Whether to include the final swaps in the QFT. inverse: If True, the inverse Fourier transform is constructed. insert_barriers: If True, barriers are inserted as visualization improvement. name: The name of the circuit. NIQFTr r)super__init___approximation_degree _do_swaps_insert_barriers_inverser)selfrrrrrr __class__s ]/granary/edev/quantum/lib/python3.11/site-packages/qiskit/circuit/library/basis_change/qft.pyrz QFT.__init__Ns\6 <$/66%D d###%9"! / $c*tjS)ztThe number of qubits in the QFT circuit. Returns: The number of qubits in the circuit. )rr)r$r%s r&rzQFT.num_qubitsssww!!r'c||jkr<|g|_|!|dkrt|dg|_dSdSdSdS)zSet the number of qubits. Note that this changes the registers of the circuit. Args: num_qubits: The new number of qubits. Nrqr)r _invalidateqregsr)r$rs r&rzQFT.num_qubits~sg  ( (      DJ%*q..-jsCCCD ) (&%..r'c|jS)zsThe approximation degree of the QFT. Returns: The currently set approximation degree. )r r$s r&rzQFT.approximation_degrees ))r'c|dkrtd||jkr|||_dSdS)zSet the approximation degree of the QFT. Args: approximation_degree: The new approximation degree. Raises: ValueError: If the approximation degree is smaller than 0. rz.Approximation degree cannot be smaller than 0.N) ValueErrorr r+)r$rs r&rzQFT.approximation_degreesT ! # #MNN N 4#= = =      )=D & & & > =r'c|jS)zWhether barriers are inserted for better visualization or not. Returns: True, if barriers are inserted, False if not. )r"r.s r&rzQFT.insert_barrierss $$r'cV||jkr|||_dSdS)zSpecify whether barriers are inserted for better visualization or not. Args: insert_barriers: If True, barriers are inserted, if False not. N)r"r+)r$rs r&rzQFT.insert_barrierss: d3 3 3      $3D ! ! ! 4 3r'c|jS)zWhether the final swaps of the QFT are applied or not. Returns: True, if the final swaps are applied, False if not. )r!r.s r&rz QFT.do_swapss ~r'cV||jkr|||_dSdS)zSpecify whether to do the final swaps of the QFT circuit or not. Args: do_swaps: If True, the final swaps are applied, if False not. N)r!r+)r$rs r&rz QFT.do_swapss6 t~ % %      %DNNN & %r'c|jS)zWhether the inverse Fourier transform is implemented. Returns: True, if the inverse Fourier transform is implemented, False otherwise. )r#r.s r& is_inversezQFT.is_inverses }r' annotated'QFT'cd|jdvr |jrdnd}n |jdz}||}|jdj}||_|j|t||j g|j |_|S)amInvert this circuit. Args: annotated: indicates whether the inverse gate can be implemented as an annotated gate. The value of this argument is ignored as the inverse of a QFT is an IQFT which is just another instance of :class:`.QFT`. Returns: The inverted circuit. )r rr r_dgrr) rr#copydata operationrclear_appendrqubits)r$r7rinvertediqfts r&rz QFT.inverses 9 ' ' M555vDD9u$D99$9''y|%--//  +D(/2FFGGG $ -r'raise_on_failurec>d}|jd}|rtd|S)z,Check if the current configuration is valid.TNFz&The number of qubits has not been set.)rAttributeError)r$rCvalids r&_check_configurationzQFT._check_configurations1 ? "E O$%MNNN r'cp|jrdSt|j}|dkrdSddlm}|||j|j|j|j |j }|j r| n| }|||jddS)z(If not already built, build the circuit.Nrsynth_qft_full)rrrrrT)r@inplace) _is_builtr_buildrqiskit.synthesis.qftrJr!r"r r#rrto_instructionto_gatecomposer@)r$rrJcircuitwrappedr%s r&rMz QFT._builds >  F _ ?? F777777 . ^ 1!%!;M    /3.BY'((***HYHY WT[$ ?????r')NrTFFN)rrrrrrrrrrrrrr)rr)rrrr)rrrr)rr)rrrr)rrrr)F)r7rrr8)T)rCrrr)rr)__name__ __module__ __qualname____doc__rrpropertyrsetterrrrr6rrGrM __classcell__r%s@r&r r s44l^  "&$% %%%%%%%%:"""""X" E E E E***X* >>>! > %%%X%4444X_&&&_&<@@@@@@@@@@r'r c6eZdZdZdfd ZedfdZdZxZS) QFTGatezQuantum Fourier Transform Gate. The Quantum Fourier Transform (QFT) on :math:`n` qubits is the operation .. math:: |j\rangle \mapsto \frac{1}{2^{n/2}} \sum_{k=0}^{2^n - 1} e^{2\pi ijk / 2^n} |k\rangle rrcPtd|gdS)z[ Args: num_qubits: The number of qubits on which the QFT acts. qft)rrparamsN)rr)r$rr%s r&rzQFTGate.__init__%s* e 2FFFFFr'Nc|durtd|j}tjd|z}tj||}tjdtjz|zd|zz|d|dz zzS)z%Return a numpy array for the QFTGate.Fz9unable to avoid copy while creating an array as requestedry@g?)dtype)r0rnparangeouterexppi)r$rbr;nnumsres r& __array__zQFTGate.__array__/sz 5==XYY Y OyAt$$vb25j5(CF35AAASQQRU^TTr'c>ddlm}||j|_dS)zGProvide a specific decomposition of the QFTGate into a quantum circuit.rrI)rN)rNrJr definition)r$rJs r&_definezQFTGate._define8s.777777(.DODDDr')rr) rTrUrVrWrcomplexrjrmrZr[s@r&r]r]sGGGGGG&DUUUUEEEEEEEr'r])rW __future__rnumpyrcqiskit.circuit.quantumcircuitrrrqiskit.utils.deprecationrblueprintcircuitr r r]r'r&rusTS""""""SSSSSSSSSS333333//////@@@@@@@@@@ @@@@@@F"E"E"E"E"Ed"E"E"E"E"Er'