Quantum-buffers.qs

// Explanation:
// 1. Buffer Allocation:
// AllocateBuffer dynamically creates an array of qubits to represent a quantum buffer. A message logs the allocation.
// 
// 2. Buffer Usage:
// UseBuffer applies a set of operations (e.g., Hadamard gates) to all qubits in the buffer, simulating the use of allocated quantum memory.
// 
// 3. Garbage Collection:
// FreeBuffer ensures all qubits are reset to their ground state before deallocation to prevent quantum garbage from affecting future computations.
// 
// 4. Management Workflow:
// ManageBuffersAndGarbageCollection integrates allocation, usage, and deallocation for comprehensive buffer management.
// 
// 5. Entry Point:
// The Main operation demonstrates the process, initializing a buffer size and invoking the management routine.

// Namespace and Imports
// namespace Quantum.BufferManagement 
// Defines the logical scope for the code, allowing organization of related operations under a single namespace.
namespace Quantum.BufferManagement {

    // Provides access to intrinsic quantum operations, like H (Hadamard gate) and Reset.
    open Microsoft.Quantum.Intrinsic;


    // Includes canonical quantum operations and higher-level abstractions often used in quantum programs.
    open Microsoft.Quantum.Canon;

    // Declares an operation to allocate a quantum buffer of size qubits, returning an array of Qubit.
    operation AllocateBuffer(size : Int) : Qubit[] {

        // Allocates an array of size qubits, which will be automatically deallocated when the use block ends.
        // Allocate a quantum buffer of given size
        use qubits = Qubit[size];

        // Outputs a message to log the allocation for debugging or monitoring purposes.
        Message($"Buffer of size {size} allocated.");

        // Returns the allocated buffer (array of qubits) to the caller.
        return qubits;
    }
    
    // Declares an operation to perform quantum computations on the given buffer of qubits.
    operation UseBuffer(qubits : Qubit[]) : Unit {
        // Apply some quantum operations to the buffer
        for (q in qubits) {

            // Applies the Hadamard gate to the current qubit, placing it into an equal superposition state.
            H(q); // Apply Hadamard gate to each qubit

        }

        // Logs a message indicating that operations were successfully applied to all qubits in the buffer.
        Message($"Operations applied to the buffer.");
    }

    // Declares an operation to safely deallocate the quantum buffer by resetting all qubits.
    operation FreeBuffer(qubits : Qubit[]) : Unit {
        // Deallocate the quantum buffer
        for (q in qubits) {

            // Ensures that the qubit is reset to the ground state (∣0⟩∣0⟩) before deallocation. 
            // This is critical for avoiding quantum garbage.
            Reset(q);
        }

        // Logs the size of the buffer and confirms that it has been freed.
        Message($"Buffer of size {Length(qubits)} freed.");
    }

    // A higher-level operation that orchestrates allocation, use, and deallocation of quantum buffers.
    operation ManageBuffersAndGarbageCollection(size : Int) : Unit {

        // Calls AllocateBuffer to create a buffer of size qubits and assigns it to a mutable variable buffer.
        // Main operation to manage buffers and garbage collection
        mutable buffer = AllocateBuffer(size);

        // Calls UseBuffer to perform operations on the allocated buffer.
        UseBuffer(buffer);

        // Calls FreeBuffer to reset and deallocate the buffer, ensuring no quantum garbage is left.
        FreeBuffer(buffer);
    }

    // Marks the Main operation as the starting point of the program when executed.
    @EntryPoint()

    // Declares the main entry operation for the program.
    operation Main() : Unit {

        // Sets the buffer size to 5 qubits for this example.
        let bufferSize = 5;

        // Calls the ManageBuffersAndGarbageCollection operation with the defined buffer size to demonstrate the workflow.
        ManageBuffersAndGarbageCollection(bufferSize);
    }
}