microsoft/qdk
Publicmirrored fromhttps://github.com/microsoft/qdkAvailable
samples/algorithms/GHZ.qs
52lines · modecode
| 1 | /// # Sample |
| 2 | /// GHZ |
| 3 | /// |
| 4 | /// # Description |
| 5 | /// The Greenberger–Horne–Zeilinger state, or GHZ state, is a state with 3 |
| 6 | /// qubits defined as: |GHZ〉 = (|000〉 + |111〉) / √2. |
| 7 | /// |
| 8 | /// The GHZ state is said to be a maximally entangled state, a multi-qubit |
| 9 | /// state where the state of any one qubit is not separable from the state |
| 10 | /// of any of the other qubits. |
| 11 | /// |
| 12 | /// The generalized form of the GHZ state across any number of qubits is |
| 13 | /// called a cat state, and the GHZ state is a special case of the cat |
| 14 | /// state where the number of qubits is 3. |
| 15 | /// |
| 16 | /// This Q# program prepares the GHZ state in a register of 3 qubits, then |
| 17 | /// returns the result of measuring those qubits. |
| 18 | namespace Sample { |
| 19 | open Microsoft.Quantum.Diagnostics; |
| 20 | open Microsoft.Quantum.Measurement; |
| 21 | |
| 22 | @EntryPoint() |
| 23 | operation Main() : Result[] { |
| 24 | use qs = Qubit[3]; |
| 25 | |
| 26 | // Prepare a GHZ state using the allocated register. |
| 27 | PrepareGHZState(qs); |
| 28 | |
| 29 | // Show the GHZ state. |
| 30 | DumpMachine(); |
| 31 | |
| 32 | // Measure and reset qubits before releasing them. |
| 33 | let results = MeasureEachZ(qs); |
| 34 | ResetAll(qs); |
| 35 | return results; |
| 36 | } |
| 37 | |
| 38 | /// # Summary |
| 39 | /// This operation prepares a generalized GHZ state across a register of qubits. |
| 40 | /// |
| 41 | /// # Input |
| 42 | /// ## qs |
| 43 | /// The given register of qubits to be transformed into the GHZ state. It is assumed |
| 44 | /// that these qubits are in their default |0〉 state. |
| 45 | operation PrepareGHZState(qs : Qubit[]) : Unit { |
| 46 | Fact(Length(qs) > 0, "`qs` length must be greater than zero"); |
| 47 | Fact(CheckAllZero(qs), "All qubits must be in the |0〉 state"); |
| 48 | |
| 49 | H(qs[0]); |
| 50 | ApplyToEach(CNOT(qs[0], _), qs[1...]); |
| 51 | } |
| 52 | } |