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""" |
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qasm.py - Functions to parse a set of qasm commands into a SymPy Circuit. |
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Examples taken from Chuang's page: https://web.archive.org/web/20220120121541/https://www.media.mit.edu/quanta/qasm2circ/ |
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The code returns a circuit and an associated list of labels. |
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>>> from sympy.physics.quantum.qasm import Qasm |
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>>> q = Qasm('qubit q0', 'qubit q1', 'h q0', 'cnot q0,q1') |
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>>> q.get_circuit() |
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CNOT(1,0)*H(1) |
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>>> q = Qasm('qubit q0', 'qubit q1', 'cnot q0,q1', 'cnot q1,q0', 'cnot q0,q1') |
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>>> q.get_circuit() |
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CNOT(1,0)*CNOT(0,1)*CNOT(1,0) |
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""" |
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__all__ = [ |
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'Qasm', |
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] |
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from math import prod |
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from sympy.physics.quantum.gate import H, CNOT, X, Z, CGate, CGateS, SWAP, S, T,CPHASE |
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from sympy.physics.quantum.circuitplot import Mz |
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def read_qasm(lines): |
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return Qasm(*lines.splitlines()) |
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def read_qasm_file(filename): |
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return Qasm(*open(filename).readlines()) |
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def flip_index(i, n): |
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"""Reorder qubit indices from largest to smallest. |
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>>> from sympy.physics.quantum.qasm import flip_index |
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>>> flip_index(0, 2) |
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1 |
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>>> flip_index(1, 2) |
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0 |
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""" |
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return n-i-1 |
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def trim(line): |
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"""Remove everything following comment # characters in line. |
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>>> from sympy.physics.quantum.qasm import trim |
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>>> trim('nothing happens here') |
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'nothing happens here' |
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>>> trim('something #happens here') |
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'something ' |
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""" |
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if '#' not in line: |
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return line |
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return line.split('#')[0] |
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def get_index(target, labels): |
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"""Get qubit labels from the rest of the line,and return indices |
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>>> from sympy.physics.quantum.qasm import get_index |
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>>> get_index('q0', ['q0', 'q1']) |
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1 |
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>>> get_index('q1', ['q0', 'q1']) |
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0 |
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""" |
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nq = len(labels) |
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return flip_index(labels.index(target), nq) |
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def get_indices(targets, labels): |
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return [get_index(t, labels) for t in targets] |
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def nonblank(args): |
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for line in args: |
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line = trim(line) |
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if line.isspace(): |
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continue |
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yield line |
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return |
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def fullsplit(line): |
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words = line.split() |
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rest = ' '.join(words[1:]) |
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return fixcommand(words[0]), [s.strip() for s in rest.split(',')] |
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def fixcommand(c): |
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"""Fix Qasm command names. |
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Remove all of forbidden characters from command c, and |
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replace 'def' with 'qdef'. |
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""" |
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forbidden_characters = ['-'] |
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c = c.lower() |
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for char in forbidden_characters: |
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c = c.replace(char, '') |
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if c == 'def': |
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return 'qdef' |
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return c |
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def stripquotes(s): |
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"""Replace explicit quotes in a string. |
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>>> from sympy.physics.quantum.qasm import stripquotes |
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>>> stripquotes("'S'") == 'S' |
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True |
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>>> stripquotes('"S"') == 'S' |
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True |
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>>> stripquotes('S') == 'S' |
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True |
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""" |
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s = s.replace('"', '') |
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s = s.replace("'", '') |
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return s |
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class Qasm: |
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"""Class to form objects from Qasm lines |
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>>> from sympy.physics.quantum.qasm import Qasm |
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>>> q = Qasm('qubit q0', 'qubit q1', 'h q0', 'cnot q0,q1') |
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>>> q.get_circuit() |
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CNOT(1,0)*H(1) |
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>>> q = Qasm('qubit q0', 'qubit q1', 'cnot q0,q1', 'cnot q1,q0', 'cnot q0,q1') |
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>>> q.get_circuit() |
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CNOT(1,0)*CNOT(0,1)*CNOT(1,0) |
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""" |
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def __init__(self, *args, **kwargs): |
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self.defs = {} |
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self.circuit = [] |
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self.labels = [] |
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self.inits = {} |
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self.add(*args) |
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self.kwargs = kwargs |
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def add(self, *lines): |
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for line in nonblank(lines): |
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command, rest = fullsplit(line) |
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if self.defs.get(command): |
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function = self.defs.get(command) |
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indices = self.indices(rest) |
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if len(indices) == 1: |
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self.circuit.append(function(indices[0])) |
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else: |
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self.circuit.append(function(indices[:-1], indices[-1])) |
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elif hasattr(self, command): |
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function = getattr(self, command) |
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function(*rest) |
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else: |
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print("Function %s not defined. Skipping" % command) |
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def get_circuit(self): |
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return prod(reversed(self.circuit)) |
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def get_labels(self): |
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return list(reversed(self.labels)) |
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def plot(self): |
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from sympy.physics.quantum.circuitplot import CircuitPlot |
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circuit, labels = self.get_circuit(), self.get_labels() |
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CircuitPlot(circuit, len(labels), labels=labels, inits=self.inits) |
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def qubit(self, arg, init=None): |
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self.labels.append(arg) |
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if init: self.inits[arg] = init |
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def indices(self, args): |
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return get_indices(args, self.labels) |
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def index(self, arg): |
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return get_index(arg, self.labels) |
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def nop(self, *args): |
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pass |
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def x(self, arg): |
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self.circuit.append(X(self.index(arg))) |
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def z(self, arg): |
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self.circuit.append(Z(self.index(arg))) |
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def h(self, arg): |
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self.circuit.append(H(self.index(arg))) |
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def s(self, arg): |
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self.circuit.append(S(self.index(arg))) |
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def t(self, arg): |
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self.circuit.append(T(self.index(arg))) |
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def measure(self, arg): |
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self.circuit.append(Mz(self.index(arg))) |
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def cnot(self, a1, a2): |
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self.circuit.append(CNOT(*self.indices([a1, a2]))) |
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def swap(self, a1, a2): |
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self.circuit.append(SWAP(*self.indices([a1, a2]))) |
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def cphase(self, a1, a2): |
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self.circuit.append(CPHASE(*self.indices([a1, a2]))) |
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def toffoli(self, a1, a2, a3): |
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i1, i2, i3 = self.indices([a1, a2, a3]) |
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self.circuit.append(CGateS((i1, i2), X(i3))) |
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def cx(self, a1, a2): |
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fi, fj = self.indices([a1, a2]) |
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self.circuit.append(CGate(fi, X(fj))) |
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def cz(self, a1, a2): |
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fi, fj = self.indices([a1, a2]) |
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self.circuit.append(CGate(fi, Z(fj))) |
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def defbox(self, *args): |
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print("defbox not supported yet. Skipping: ", args) |
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def qdef(self, name, ncontrols, symbol): |
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from sympy.physics.quantum.circuitplot import CreateOneQubitGate, CreateCGate |
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ncontrols = int(ncontrols) |
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command = fixcommand(name) |
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symbol = stripquotes(symbol) |
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if ncontrols > 0: |
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self.defs[command] = CreateCGate(symbol) |
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else: |
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self.defs[command] = CreateOneQubitGate(symbol) |
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