math

A tiny math library which will be extended thoughout the next weeks. Right now, it only contains the math functions necessary to run Beauregard’s implementation of Shor’s algorithm.

Module contents

class projectq.libs.math.AddConstant(a)

Add a constant to a quantum number represented by a quantum register, stored from low- to high-bit.

Example

qunum = eng.allocate_qureg(5) # 5-qubit number
X | qunum[1] # qunum is now equal to 2
AddConstant(3) | qunum # qunum is now equal to 5

__init__(a)

Initializes the gate to the number to add.

Parameters:a (int) – Number to add to a quantum register.

It also initializes its base class, BasicMathGate, with the corresponding function, so it can be emulated efficiently.

get_inverse()

Return the inverse gate (subtraction of the same constant).

class projectq.libs.math.AddConstantModN(a, N)

Add a constant to a quantum number represented by a quantum register modulo N.

The number is stored from low- to high-bit, i.e., qunum[0] is the LSB.

Example

qunum = eng.allocate_qureg(5) # 5-qubit number
X | qunum[1] # qunum is now equal to 2
AddConstantModN(3, 4) | qunum # qunum is now equal to 1

__init__(a, N)

Initializes the gate to the number to add modulo N.

Parameters:

• a (int) – Number to add to a quantum register (0 <= a < N).
• N (int) – Number modulo which the addition is carried out.

It also initializes its base class, BasicMathGate, with the corresponding function, so it can be emulated efficiently.

get_inverse()

Return the inverse gate (subtraction of the same number a modulo the same number N).

class projectq.libs.math.MultiplyByConstantModN(a, N)

Multiply a quantum number represented by a quantum register by a constant modulo N.

The number is stored from low- to high-bit, i.e., qunum[0] is the LSB.

Example

qunum = eng.allocate_qureg(5) # 5-qubit number
X | qunum[2] # qunum is now equal to 4
MultiplyByConstantModN(3,5) | qunum # qunum is now equal to 2 (mod 5)

__init__(a, N)

Initializes the gate to the number to multiply with modulo N.

Parameters:

• a (int) – Number by which to multiply a quantum register (0 <= a < N).
• N (int) – Number modulo which the multiplication is carried out.

It also initializes its base class, BasicMathGate, with the corresponding function, so it can be emulated efficiently.

projectq.libs.math.SubConstant(a)

Subtract a constant from a quantum number represented by a quantum register, stored from low- to high-bit.

Parameters:a (int) – Constant to subtract

Example

qunum = eng.allocate_qureg(5) # 5-qubit number
X | qunum[2] # qunum is now equal to 4
SubConstant(3) | qunum # qunum is now equal to 1

projectq.libs.math.SubConstantModN(a, N)

Subtract a constant from a quantum number represented by a quantum register modulo N.

The number is stored from low- to high-bit, i.e., qunum[0] is the LSB.

Parameters:

• a (int) – Constant to add
• N (int) – Constant modulo which the addition of a should be carried out.

Example

qunum = eng.allocate_qureg(3) # 3-qubit number
X | qunum[1] # qunum is now equal to 2
SubConstantModN(4,5) | qunum # qunum is now equal to -2 = 6 = 1 (mod 5)