microsoft/qdk
Publicmirrored fromhttps://github.com/microsoft/qdkAvailable
katas/content/key_distribution/examples/BB84Demo.qs
71lines · modecode
| 1 | namespace Kata { |
| 2 | open Microsoft.Quantum.Arrays; |
| 3 | open Microsoft.Quantum.Convert; |
| 4 | open Microsoft.Quantum.Diagnostics; |
| 5 | open Microsoft.Quantum.Random; |
| 6 | |
| 7 | @EntryPoint() |
| 8 | operation RunBB84Protocol() : Unit { |
| 9 | // 1. Alice chooses a random set of bits to encode in her qubits |
| 10 | // and a random set of bases to prepare her qubits in. |
| 11 | // ... |
| 12 | |
| 13 | // 2. Alice allocates qubits, encodes them using her choices and sends them to Bob. |
| 14 | // You can not express "sending the qubits to Bob" in Q#, |
| 15 | // so Bob will just use the same qubits. |
| 16 | // ... |
| 17 | |
| 18 | // 3. Bob chooses a random set of bases to measure Alice's qubits in. |
| 19 | // ... |
| 20 | |
| 21 | // 4. Bob measures Alice's qubits in his chosen bases. |
| 22 | // ... |
| 23 | |
| 24 | // 5. Alice and Bob compare their chosen bases and |
| 25 | // use the bits in the matching positions to create a shared key. |
| 26 | // ... |
| 27 | |
| 28 | // If you did everything correctly, the generated keys will always match, |
| 29 | // since there is no eavesdropping going on. |
| 30 | // In the next lesson we will discuss introducing eavesdropping. |
| 31 | } |
| 32 | |
| 33 | // You might find these helper operations from earlier tasks useful. |
| 34 | operation RandomArray(N : Int) : Bool[] { |
| 35 | mutable array = [false, size = N]; |
| 36 | for i in 0 .. N - 1 { |
| 37 | set array w/= i <- DrawRandomInt(0, 1) == 0; |
| 38 | } |
| 39 | return array; |
| 40 | } |
| 41 | |
| 42 | operation PrepareQubits(qs : Qubit[], bases : Bool[], bits : Bool[]) : Unit { |
| 43 | for i in 0 .. Length(qs) - 1 { |
| 44 | if bits[i] { |
| 45 | X(qs[i]); |
| 46 | } |
| 47 | if bases[i] { |
| 48 | H(qs[i]); |
| 49 | } |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | operation MeasureQubits(qs : Qubit[], bases : Bool[]) : Bool[] { |
| 54 | for i in 0 .. Length(qs) - 1 { |
| 55 | if bases[i] { |
| 56 | H(qs[i]); |
| 57 | } |
| 58 | } |
| 59 | return ResultArrayAsBoolArray(MeasureEachZ(qs)); |
| 60 | } |
| 61 | |
| 62 | function GenerateSharedKey(basesAlice : Bool[], basesBob : Bool[], bits : Bool[]) : Bool[] { |
| 63 | mutable key = []; |
| 64 | for i in 0 .. Length(bits) - 1 { |
| 65 | if basesAlice[i] == basesBob[i] { |
| 66 | set key += [bits[i]]; |
| 67 | } |
| 68 | } |
| 69 | return key; |
| 70 | } |
| 71 | } |
| 72 | |