Merge branch 'master' of https://github.com/QuantumBFS/tutorials

developer-guide/2.cuda-acceleration/main.jl

@@ -34,4 +34,3 @@
 # Only if two qubits at `locs` are $0$ and $1$ respectively, they are exchanged, otherwise do nothing.
 # Although $3/4$ of threads are idle and plenty room for optimization, from this example, we see how easy CUDA programming is with
 # [CUDAnative](https://github.com/JuliaGPU/CUDAnative.jl).
-# In appendix \App{app-reg}, we show another example of creating a register that echos received instructions.

quick-start/5.shor-9-code/main.jl

@@ -21,7 +21,7 @@ shor(E) = chain(9,
 )
 
 # Now we can check whether it can correct a given error by doing symbolic computation
-# on a 1-qubit quantum state ``α|0⟩ + β|1⟩`` and an arbitrary weight-9 error.
+# on an arbitrary 1-qubit pure quantum state ``α|0⟩ + β|1⟩`` and a specific weight-9 error.
 
 @vars α β
 s = α * ket"0" + β * ket"1" |> addbits!(8)

quick-start/7.variation-quantum-eigen-solver/main.jl

@@ -2,36 +2,26 @@
 
 using Yao, Yao.AD, YaoExtensions
 
-
-using YaoExtensions: get_diffblocks, _perturb
-using StatsBase
-
-function _expect(op::AbstractBlock, reg::ArrayReg; nshots=nothing)
-    if nshots === nothing
-        expect(op, reg)
-    else
-        mean(measure(op, copy(reg); nshots=nshots))
-    end
-end
-
-@inline function my_faithful_grad(op::AbstractBlock, pair::Pair{<:ArrayReg, <:AbstractBlock}; nshots=nothing)
-    map(get_diffblocks(pair.second)) do diffblock
-        r1, r2 = _perturb(()->_expect(op, copy(pair.first) |> pair.second; nshots=nshots) |> real, diffblock, π/2)
-        (r2 - r1)/2
-    end
-end
-
+# number of qubits
 n = 4
+
+# depth
 d = 5
 circuit = dispatch!(variational_circuit(n, d),:random)
 
 gatecount(circuit)
 
+nparameters(circuit)
+
 h = heisenberg(n)
 
-for i in 1:1000
-      grad = my_faithful_grad(h, zero_state(n) => circuit; nshots=100)
+# pick the one you like
+# either reverse-mode
+# or forward mode
+# grad = faithful_grad(h, zero_state(n) => circuit; nshots=100)
 
+for i in 1:1000
+      _, grad = expect'(h, zero_state(n) => circuit)
       dispatch!(-, circuit, 1e-2 * grad)
       println("Step $i, energy = $(real.(expect(h, zero_state(n)=>circuit)))")
 end