Qadence Transition (#34)

* legacy prototype 14/01/2025

* remove folder from tracking

* test

* test

* block system

* check

* block system done

* parameters

* reorganize

* function lists

* complete transition.md

* complete transition.md

* apply review

---------

Co-authored-by: Sungwoo AHN <[email protected]>

docs/transition.md

@@ -0,0 +1,192 @@
+
+# Transition Guide
+This document is for Qadence users to use Qadence2 funcationalities with Qadence format.
+For Qadence2 code details, please refer to https://github.com/pasqal-io/qadence2-core.
+
+## Operators
+
+Qadence operators can be used in the same way (including the order of target and control) in Qadence 2.
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence import RX, CNOT
+
+rx = RX(0, 0.5)
+cnot = CNOT(0, 1)
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence2.extensions.legacy import RX, CNOT
+
+rx = RX(0, 0.5)
+cnot = CNOT(0, 1)
+```
+
+## Block System
+
+Building quantum expressions with `chain` and `kron` is also identical.
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence import X, Y, chain, kron
+
+chain_0 = chain(X(0), Y(0))
+chain_1 = chain(X(1), Y(1))
+
+kron_block = kron(chain_0, chain_1)
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence2.extensions.legacy import X, Y, chain, kron
+
+chain_0 = chain(X(0), Y(0))
+chain_1 = chain(X(1), Y(1))
+
+kron_block = kron(chain_0, chain_1)
+```
+
+## Compose Functions
+
+Custom gates can also be applied in the same way, and with the definition change, Qadence2 now use `*` instead of `@`.
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence import X, Y, add
+
+def xy_int(i: int, j: int):
+    return (1/2) * (X(i)@X(j) + Y(i)@Y(j))
+
+n_qubits = 3
+
+xy_ham = add(xy_int(i, i+1) for i in range(n_qubits-1))
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence2.extensions.legacy import X, Y, add
+
+def xy_int(i: int, j: int):
+    return (1/2) * (X(i)*X(j) + Y(i)*Y(j))
+
+n_qubits = 3
+
+xy_ham = add(xy_int(i, i+1) for i in range(n_qubits-1))
+```
+
+## Quantum Fourier Transform Example
+
+The code initializes a quantum circuit with `CPHASE` gates and applies `qft_layer` to transform the input quantum state into its frequency domain representation.
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence import H, CPHASE, PI, chain, kron
+
+def qft_layer(qs: tuple, l: int):
+    cphases = chain(CPHASE(qs[j], qs[l], PI/2**(j-l)) for j in range(l+1, len(qs)))
+    return H(qs[l]) * cphases
+
+def qft(qs: tuple):
+    return chain(qft_layer(qs, l) for l in range(len(qs)))
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence2.extensions.legacy import H, CPHASE, PI, chain, kron
+
+def qft_layer(qs: tuple, l: int):
+    cphases = chain(CPHASE(qs[j], qs[l], PI/2**(j-l)) for j in range(l+1, len(qs)))
+    return H(qs[l]) * cphases
+
+def qft(qs: tuple):
+    return chain(qft_layer(qs, l) for l in range(len(qs)))
+```
+
+
+## Quantum Models
+
+Qadence2 uses `Expression` and `IR` to represent the details of the quantum circuits and algorithms and `Platform` to match the executing backend, whereas Qadence is not separated.
+As a result, Qadence can call `run,` `sample,` and `expectation` with the circuit representation itself.
+However, Qadence2 requires it first to be compiled to execute them with the backends.
+Qadence2 uses `compile_to_model` and `compile_to_backend` to compile them into `model` and `compiled_model,` respectively. After this procedure, it is only ready to execute `run,` `sample,` and `expectation.`
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+import torch
+from qadence import QuantumModel, PI, Z
+from qadence import QuantumCircuit, RX, RY, chain, kron
+from qadence import FeatureParameter, VariationalParameter
+
+phi = FeatureParameter("phi")
+
+block = chain(
+    kron(RX(0, phi), RY(1, phi)),
+)
+
+circuit = QuantumCircuit(2, block)
+
+observable = Z(0) + Z(1)
+
+model = QuantumModel(circuit, observable)
+
+values = {"phi": torch.tensor(PI)}
+
+wf = model.run(values)
+xs = model.sample(values, n_shots=100)
+ex = model.expectation(values)
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+import torch
+from qadence2.extensions.legacy import PI, Z, RX, RY, chain, kron
+from qadence2_expressions import compile_to_model, parameter
+from qadence2_platforms.compiler import compile_to_backend
+
+phi = parameter("phi")
+
+block = chain(
+    kron(RX(0, phi), RY(1, phi)),
+)
+
+model = compile_to_model(block)
+compiled_model = compile_to_backend(model, "pyqtorch")
+
+observable = Z(0) + Z(1)
+
+values = {"phi": torch.tensor(PI)}
+
+wf = compiled_model.run(values)
+xs = compiled_model.sample(values, shots=100)
+ex = compiled_model.expectation(values, observable=observable)
+```
+
+## Quantum Registers
+
+Qadence2 can represent the relationships between qubits using `grid_type`, `grid_scale`, and `qubit_position`. The `connectivity` in `qadence2_ir` is for accurately representing the connectivity between qubits.
+
+Qadence
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence import Register
+
+reg = Register.all_to_all(n_qubits = 4)
+reg_line = Register.line(n_qubits = 4)
+reg_squre = Register.square(qubits_side = 2)
+reg_triang = Register.triangular_lattice(n_cells_row = 2, n_cells_col = 2)
+```
+
+Qadence2
+```python exec="on" source="material-block" html="1" session="getting_started"
+from qadence2_expressions.core import set_grid_type, set_qubits_positions, set_grid_scale
+from qadence2.extensions.legacy import PI, RX, RY, CZ
+from qadence2_expressions import compile_to_model
+
+expr = RX(2, PI / 2) * CZ() * RY(0, PI / 2)
+
+set_grid_type("linear")  # "square", "triangular"
+set_qubits_positions([(-2, 1), (0, 0), (3, 1)])
+set_grid_scale(0.4)
+
+compile_to_model(expr)
+```

mkdocs.yml

@@ -5,6 +5,7 @@ repo_name: "qadence2_core"
 nav:
   - Overview: index.md
   - Sample page: getting_started_example.md
+  - Qadence transition: transition.md
 
 theme:
   name: material

qadence2/extensions/legacy/__init__.py

@@ -1,10 +1,10 @@
 from __future__ import annotations
 
-from qadence2_expressions.operators import CZ, X, Y, Z
+from qadence2_expressions.operators import CZ, H, X, Y, Z
 
 from .model import QuantumModel
-from .operators import CNOT, RX, RY, RZ, N
-from .utils import add, chain, kron, mul, pow
+from .operators import CNOT, CPHASE, PHASE, RX, RY, RZ, N, T
+from .utils import PI, add, chain, kron, mul, pow
 
 __all__ = [
     "QuantumModel",
@@ -22,4 +22,9 @@
     "Z",
     "CZ",
     "N",
+    "PI",
+    "H",
+    "T",
+    "PHASE",
+    "CPHASE",
 ]

qadence2/extensions/legacy/operators.py

@@ -2,13 +2,19 @@
 
 import qadence2_expressions.operators as ops
 from qadence2_expressions import variable
+from qadence2_expressions.core.constructors import (
+    parametric_operator,
+    promote,
+    unitary_hermitian_operator,
+)
 from qadence2_expressions.core.expression import Expression
+from qadence2_expressions.operators import _join_rotation
 
 # The N = (1/2)(I-Z) operator
 N = ops.Z1
 
 
-def CNOT(target: int, control: int) -> Expression:
+def CNOT(control: int, target: int) -> Expression:
     return ops.NOT(target=(target,), control=(control,))
 
 
@@ -29,3 +35,19 @@ def _get_variable(expr: Expression | str | float) -> Expression:
         return variable(expr)
     if isinstance(expr, (Expression, float)):
         return expr
+
+
+def T(target: int) -> Expression:
+    return unitary_hermitian_operator("T")(target=(target,))
+
+
+def PHASE(target: int, parameters: Expression | str | float) -> Expression:
+    return parametric_operator("PHASE", promote(_get_variable(parameters)), join=_join_rotation)(
+        target=(target,)
+    )
+
+
+def CPHASE(control: int, target: int, parameters: Expression | str | float) -> Expression:
+    return parametric_operator("CPHASE", promote(_get_variable(parameters)), join=_join_rotation)(
+        target=(target,), control=(control,)
+    )

qadence2/extensions/legacy/utils.py

@@ -1,10 +1,13 @@
 from __future__ import annotations
 
+import math
 from enum import Enum, auto
 from typing import Generator
 
 from qadence2_expressions.core.expression import Expression
 
+PI = math.pi
+
 
 class ParadigmStrategy(Enum):
     DIGITAL = auto()
@@ -14,21 +17,29 @@ class ParadigmStrategy(Enum):
     RYDBERG = auto()
 
 
-def add(expr: Generator | list[Expression]) -> Expression:
-    return Expression.add(*tuple(expr))
+def add(*expr: Generator | list[Expression]) -> Expression:
+    if len(expr) > 0 and isinstance(expr[0], Generator):
+        return Expression.add(*tuple(*expr))
+    return Expression.add(*expr)
 
 
-def mul(expr: Generator | list[Expression]) -> Expression:
-    return Expression.mul(*tuple(expr))
+def mul(*expr: Generator | list[Expression]) -> Expression:
+    if len(expr) > 0 and isinstance(expr[0], Generator):
+        return Expression.mul(*tuple(*expr))
+    return Expression.mul(*expr)
 
 
-def chain(expr: Generator | list[Expression]) -> Expression:
-    return mul(expr)
+def chain(*expr: Generator | list[Expression]) -> Expression:
+    return mul(*expr)
 
 
-def kron(expr: Generator | list[Expression]) -> Expression:
-    return Expression.kron(*tuple(expr))
+def kron(*expr: Generator | list[Expression]) -> Expression:
+    if len(expr) > 0 and isinstance(expr[0], Generator):
+        return Expression.kron(*tuple(*expr))
+    return Expression.kron(*expr)
 
 
-def pow(expr: Generator | list[Expression]) -> Expression:
-    return Expression.pow(*tuple(expr))
+def pow(*expr: Generator | list[Expression]) -> Expression:
+    if len(expr) > 0 and isinstance(expr[0], Generator):
+        return Expression.pow(*tuple(*expr))
+    return Expression.pow(*expr)