Supported python subset

Qlasskit supports a subset of python. This subset will be expanded, but it is limited by the linearity of quantum circuits and by the number of qubits.

The structure of a qlasskit function has the following pattern:

@qlasskit
def f(param: type, [...param: type]) -> type:
   statement
   ...
   statement

Types

All types has a static size.

bool

Boolean type.

Qint

Unsigned integers; Qint[2] has 2 bits, and there other sizes are supported. Single bit of the Qint are accessible by the subscript operator []. All the supported sizes have a constructor Qintn() defined in qlasskit.types.

Qfixed

Fixed point rational number; Qfixed[2,3] has 2 bits for the integer part and 3 bits for the fractional. All the supported sizes have a constructor Qfixedn_m() defined in qlasskit.types.

Qchar

A character.

Tuple

Container type holding different types.

List

Qlist[T, size] denotes a fixed-size list in qlasskit. For example, the list [1,2,3] is typed as Qlist[Qint[2],3].

Matrix

Qmatrix[T, m, n] denotes a fixed-size list in qlasskit. For example, the matrix [[1,2],[3,4]] is typed as Qmatrix[Qint[2],2,2].

Expressions

Constants

True

3.14

'a'

Tuple

(a, b)

List (fixed size)

[a, b]

2D Matrix (fixed size)

[[a, b], [c,d]]

Subscript

a[0]

Boolean operators

not a

a and b

a or b

If expressions

a if b else c

Comparators

a > b or b <= c and c == d or c != a

Unary Op

~a

Bin Op

a << 1

a >> 2

a + b

a - b

a * b

a ** b

a % 2

Note

Modulo operator only works with 2^n values.

Function call

Bultin functions:

print(): debug function, ignore by conversion
len(Tuple), len(Qlist)`: returns the length of a tuple
max(a, b, …), max(Tuple), max(Qlist): returns the max of a tuple
min(a, b, …), min(Tuple), min(Qlist): returns the min of a tuple
sum(Tuple), sum(Qlist): returns the sum of the elemnts of a tuple / list
all(Tuple), all(Qlist): returns True if all of the elemnts are True
any(Tuple), any(Qlist): returns True if any of the elemnts are True
ord(Qchar): returns the integer value of the given Qchar
chr(Qint): returns the char given its ascii code
int(Qfixed | Qint): returns the integer part of a Qfixed
float(Qint | Qfixed): returns a Qfixed representing the Qint

Statements

Assign

c = not a

Return

return b+1

For loop

for i in range(4):
   a += i

Note

Please note that in qlasskit, for loops are unrolled during compilation. Therefore, it is essential that the number of iterations for each for loop is known at the time of compilation.

Function def

def f(t: Qlist[Qint[4],2]) -> Qint[4]:
   return t[0] + t[1]

If then else

c = 0
if cond:
   c += 12
else:
   c += 13

Note

At present, the if-then-else statement in qlasskit is designed to support branch bodies that exclusively contain assignment statements.

Quantum Hybrid

In a qlassf function, you have the option to utilize quantum gates through the Q module. It’s important to keep in mind that incorporating quantum gates within a qlasskit function leads to a Python function that exhibits distinct behaviors compared to its quantum counterpart.

def bell(a: bool, b: bool) -> bool:
   return Q.CX(Q.H(a), b)