Utils.qs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

// This file includes some utility functions to set and 
// verify |+> and |-> quantum states.
namespace Microsoft.Quantum.Samples.Teleportation {
    open Microsoft.Quantum.Intrinsic;
    open Microsoft.Quantum.Canon;
    open Microsoft.Quantum.Math;

    /// # Summary
    /// Sets the qubit's state to |+⟩.
    operation SetToPlus(q: Qubit) : Unit {
        Reset(q);
        H(q);
    }

    /// # Summary
    /// Sets the qubit's state to |−⟩.
    operation SetToMinus(q: Qubit) : Unit {
        Reset(q);
        X(q);
        H(q);
    }

    /// # Summary
    /// Returns true if qubit is |+> (assumes qubit is either |+> or |->)
    operation IsPlus(q: Qubit) : Bool {
        return (Measure([PauliX], [q]) == Zero);
    }

    /// # Summary
    /// Returns true if qubit is |-> (assumes qubit is either |+> or |->)
    operation IsMinus(q: Qubit) : Bool {
        return (Measure([PauliX], [q]) == One);
    }

    /// # Summary
    /// Randomly prepares the qubit into |+> or |->
    operation PrepareRandomMessage(q: Qubit) : Unit {        
        let choice = RandomInt(2);

        if (choice == 0) {
            Message("Sending |->");
            SetToMinus(q);
        } else {
            Message("Sending |+>");
            SetToPlus(q);
        }
    }
}