Fixed integer overflow in measure

Author: Jan Lukas @ Servercraft

Project.toml

@@ -1,7 +1,7 @@
 name = "FLOYao"
 uuid = "6d9310a3-f1d0-41b7-8edb-11c1cf57cd2d"
 authors = ["janlukas.bosse <[email protected]> and contributors"]
-version = "1.6.3"
+version = "1.6.4"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

docs/src/vqe_example.md

@@ -217,14 +217,14 @@ samples = measure(reg |> circuit, nshots=10, rng=MersenneTwister(42))
 # output
 
 10-element Vector{BitStr{100, BigInt}}:
- 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ₍₂₎
- 0000000000000000000000000000000000000000101000000110000000000000000000000000000000000000000000000000 ₍₂₎
- 0000000000000000000000000000000000000000000000000000000000001101100000000011001100000001100000000000 ₍₂₎
- 0000000000000000000000000000000000000000000000000000000000000000000000000011000110000001010011000000 ₍₂₎
+ 0000000000000000000000000001111000000000000000000000000000000000000000000000000000000000000000000000 ₍₂₎
+ 0000000000000000000110011000000000000000101000000110000000000000000000000000000000000000000000000000 ₍₂₎
+ 0000000000011000110000000000000000000000000000000000000000001101100000000011001100000001100000000000 ₍₂₎
+ 1100000000000000000000001111000110000000000000000000000000000000000000000011000110000001010011000000 ₍₂₎
  0000000000000000000000000000000000000000000000000000000000001010000110000000000000000000000000000000 ₍₂₎
- 0000000000000000000000000000000000000000100100000011000000011000000000000000000000000000110000000000 ₍₂₎
- 0000000000000000000000000000000000000000000110000000000000110000100100000000000000110000000000000011 ₍₂₎
- 0000000000000000000000000000000000000010100000000000000000000000001100000000000110000000000000000000 ₍₂₎
- 0000000000000000000000000000000000000001101100000000000000000000000000000000000000000011000000000000 ₍₂₎
- 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ₍₂₎
+ 0000000000000000000000000000110000000000100100000011000000011000000000000000000000000000110000000000 ₍₂₎
+ 1100000001100000001100110000000000000000000110000000000000110000100100000000000000110000000000000011 ₍₂₎
+ 0000000000000000101000000000000000000010100000000000000000000000001100000000000110000000000000000000 ₍₂₎
+ 0000000000000000000000000001100000000001101100000000000000000000000000000000000000000011000000000000 ₍₂₎
+ 0101000000000000000000000000000011000000000000000000000000000000000000000000000000000000000000000000 ₍₂₎
 ```

src/measure.jl

@@ -93,7 +93,7 @@ end
     for i in 1:nq
         pi = (1 + covmat[2i-1,2i]) / 2
         ni = rand(rng) > pi
-        out += ni * 2^(i-1)
+        out += ni * BigInt(2)^(i-1)
         update_covariance_matrix!(covmat, i, ni ? 1-pi : pi, ni)
     end
     return out

test/runtests.jl

@@ -96,7 +96,7 @@ end
 
     # and checking integer overflow stuff
     # This first one is currently broken, but not our fault...
-    # r1 = FLOYao.product_state(Float32, lbit"11111111111111111111111111111111111111111111111111111111111111111")
+    r1 = FLOYao.product_state(Float32, Yao.lbit"11111111111111111111111111111111111111111111111111111111111111111")
     r2 = FLOYao.product_state(Float32, ones(Int, 65))
     r3 = FLOYao.product_state(Float32, 65, BigInt(2)^66 - 1)
     @test r2 ≈ r3
@@ -506,6 +506,13 @@ end
     mhist = StatsBase.normalize(fit(Histogram, Int.(msamples), nbins=2^3), mode=:probability)
     ahist = StatsBase.normalize(fit(Histogram, Int.(asamples), nbins=2^3), mode=:probability)
     @test sum(abs, ahist.weights - mhist.weights) < 0.01
+
+
+    # and with more than 64 qubits
+    bit_str = Yao.lbit"100101010010100101010010100101010010010010101001010010101001010010101001"
+    mreg = FLOYao.product_state(bit_str)
+    sample = measure(mreg) |> only
+    @test sample == bit_str
 end
 
 @testset "utils" begin