:atom_symbol: QNano

QNano is a lightweight assembly-style language for defining and compiling two-qubit quantum circuits. It's designed for rapid prototyping and provides a straightforward look into state-vector manipulation.

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:zap: Key Features

• Universal quantum gates: It can perform any quantum computation possible on two qubits. See supported gates.

• Four state vectors: Tracks ∣00⟩, ∣01⟩, ∣10⟩, ∣11⟩.

• Complex phases: Uses Complex64 to track amplitudes.

• Entanglement Support: Full CX gate implementation allows for the creation of entangled qubits.

• Custom .qnano DSL: A simple text-based assembly language for defining and loading quantum circuits.

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:file_folder: Installation

Install directly from GitHub using Cargo:

cargo install --git https://github.com/Cqsi/qnano

Once installed, you can run the simulator from any directory:

qnano bell_state.qnano

The example above uses the bell_state.qnano file that is found in the project root.

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:books: Example

Using the file bell_state.qnano, we can produce Bell's State, which represent one of the simplest examples of quantum entanglement.

The code file reads:

h 0
cx 0 1

This code translates to the following:

1. We first apply the Hadamard Gate on qubit 0, which puts the qubit in a superposition state.

2. After this we apply CNOT (Controlled-NOT), which uses qubit 0 as a control and qubit 1 as a target. This is the same as saying "If qubit 0 is 1, flip qubit 1."

Running it through the compiler gives us the final state:

Applying gates...

|00>: 0.71+0.00i
|01>: 0.00+0.00i
|10>: 0.00+0.00i
|11>: 0.71+0.00i

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:key: Supported gates

Currently supported quantum gates:

• H (Hadamard)

• X (Pauli-X / NOT)

• Z (Pauli-Z / Phase-flip)

• S (Phase / 90° rotation)

• T (T-gate / 45° rotation)

• CX (Controlled-NOT / CNOT)

• CZ (Controlled-Z)

This set of quantum gates is universal, meaning that it can in theory perform any set of quantum computation on two qubits.

See this visual for an overview of support quantum gates.

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:crystal_ball: Future improvements

Currently a work in progress.

• Ability to change initial state
• Implement Measure-gate and history
• Quantum circuit visualization using Ratatui (see archive_files)
• Writing qnano programs in the console
• Error messages

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:pencil2: Blog post

Check out the blog post Building a quantum circuit simulator which I wrote about this project.