cubeit 0.0.1

A visualisation tool for quantum information

CubeIt

CubeIt is a lightweight quantum playground for n-qubit registers. Universal gate set and utilities for visualisation and testing.

Features

• N-Qubit Registers: Create registers of any size with quantumregister(n).
• Universal Gate Set: L (h(), s(), t(), cnot(), …) (qr.h(i), qr.cnot(control, target)).
• Measurement: get_state() prints amplitudes, measure() collapses and returns classical outcomes.
• Utility Modules: Measurement statistics, Bell-state builders, fidelity checks, and more under cubeit.visualization.

Installation

pip install -r requirements.txt

Or install as a package:

pip install -e .

Quick Start

from cubeit import quantumregister, get_state, measure

# 1) Create a 4-qubit register (|0000⟩)
qr = quantumregister(4)

# 2) Build a circuit with fluent helpers
qr.h(0)          # Hadamard on qubit 0
qr.cnot(0, 1)    # Entangle qubit 0 and 1
qr.rx(2, 0.5)    # Rotate qubit 2 around X by 0.5 radians
qr.cz(1, 3)      # Controlled-Z between qubit 1 and 3

# 3) Inspect the statevector (pretty printed)
get_state(qr)

# 4) Measure – collapses the state and returns a bitstring
result = measure(qr)
print("Measurement:", result)

Gate Helpers at a Glance

Helper	Description
qr.h(i)	Hadamard on qubit i
qr.x(i), qr.y(i), qr.z(i)	Pauli gates
qr.s(i), qr.t(i)	Phase / π/8 gates
qr.rx(i, θ), qr.ry(i, θ), qr.rz(i, θ)	Rotations
qr.cnot(control, target)	Controlled-NOT
qr.cz(control, target)	Controlled-Z
qr.cphase(control, target, φ)	Controlled-phase
qr.swap(a, b)	Swap two qubits

Prefer something functional? Import directly:

from cubeit import h, cnot, quantumregister

qr = quantumregister(2)
qr.apply_single_qubit_gate(h(), 0)
qr.apply_two_qubit_gate(cnot(), 0, 1)

Measurement & Probabilities

from cubeit import quantumregister, get_state, measure
from cubeit.visualization import print_probabilities

qr = quantumregister(2).h(0).cnot(0, 1)

print_probabilities(qr)
# Measurement Probabilities:
#   |00⟩: 0.5000 (50.00%)
#   |11⟩: 0.5000 (50.00%)

measure(qr)  # collapses the register and prints the classical outcome

Bell States & Visualisation

from cubeit.visualization import create_bell_state, print_state, print_measurement_stats

bell = create_bell_state("phi_plus")
print_state(bell)                 # 0.707|00⟩ + 0.707|11⟩
print_measurement_stats(bell)     # Monte-Carlo sampling

quantumregister

Factory returning an instance of the internal _QuantumRegister. Methods:

• apply_gate(matrix) / apply_single_qubit_gate(matrix, qubit)
• measure() & measure_qubit(qubit)
• get_state() → returns a QuantumState
• get_probabilities() → np.ndarray
• Fluent helpers: h, x, y, z, s, t, phase, rx, ry, rz, cnot, cz, cphase, swap

Gate Factories

Import functions directly from cubeit when you need raw matrices:

from cubeit import h, x, cnot, swap

u = h()          # 2x2 Hadamard matrix
cx = cnot()      # 4x4 CNOT (control=0, target=1)
swap_gate = swap()

Examples

Example 1: Creating a Bell State

from cubeit import quantumregister

qr = quantumregister(2)
qr.h(0).cnot(0, 1)
print(qr)
# QuantumRegister(2 qubits):
#   0.707|00⟩ + 0.707|11⟩

Example 2: Measurement Statistics

from cubeit import quantumregister
from cubeit.visualization import print_measurement_stats

qr = quantumregister(2).h(0).cnot(0, 1)

print_measurement_stats(qr, num_samples=1000)

Theory

Universal Gate Set

The set {h, s, t, CNOT} form a universal gate set. Any unitary operation can be approximated to arbitrary precision using these primitives.

• H: Creates superposition states
• S: Applies π/2 phase rotation
• T: Applies π/4 phase rotation
• CNOT: Creates entanglement between qubits

Two-Qubit States

A two-qubit system has a 4-dimensional state space with basis states:

• |00⟩ = [1, 0, 0, 0]ᵀ
• |01⟩ = [0, 1, 0, 0]ᵀ
• |10⟩ = [0, 0, 1, 0]ᵀ
• |11⟩ = [0, 0, 0, 1]ᵀ

Any two-qubit state can be written as: |ψ⟩ = α|00⟩ + β|01⟩ + γ|10⟩ + δ|11⟩

where |α|² + |β|² + |γ|² + |δ|² = 1.

Requirements

• Python >= 3.8
• NumPy >= 1.20.0

License

See LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.