Fix kwargs bug, fix two_spin_rho bug (#38)

* Fix kwargs bug, fix two_spin_rho bug
* rename tests for analytic models, update changelog, closes #39, #40

CHANGELOG.md

@@ -2,7 +2,9 @@ QuantumAnnealing.jl Change Log
 ==============================
 
 ### Staged
-- Add Gibbs distribution
+- Add Gibbs distribution (#34)
+- Fix kwargs bug in simulate_de (#39)
+- Fix analytic two spin model for non-integer s (#40)
 
 ### v0.2.0
 - Add a generic Magnus expansion solver for any order

src/simulate_de.jl

@@ -41,7 +41,7 @@ function simulate_de(ising_model, annealing_time, annealing_schedule, reltol; ab
 
     s_range = (0.0, 1.0)
     prob = DifferentialEquations.ODEProblem(schrod_eq, initial_state, s_range, annealing_time)
-    sol = DifferentialEquations.solve(prob, abstol=abstol, reltol=reltol, alg_hints=[:nonstiff], kwargs...)
+    sol = DifferentialEquations.solve(prob; abstol=abstol, reltol=reltol, alg_hints=[:nonstiff], kwargs...)
 
     state = sol(1)
     density = state * state'

test/common.jl

@@ -45,7 +45,7 @@ end
 
 function two_spin_ρ(t; s=1.0)
     s0 = 1/2*cos(π/4*s*sqrt(1+64*t^2/π^2))*sqrt(1-sin(π/2*s)) +
-        (8im*t*sqrt(1-sin(π/2*s)) + sqrt(1+sin(π/2*s)))*sin(π/4*s*sqrt(1+64*t^2/π^2))/(2*sqrt(1+64*t^2/π^2))
+        (8im*t*sqrt(1-sin(π/2*s))/π + sqrt(1+sin(π/2*s)))*sin(π/4*s*sqrt(1+64*t^2/π^2))/(2*sqrt(1+64*t^2/π^2))
     s1 = -(cos(π/4*s*sqrt(1+64*t^2/π^2))*(1+sin(π/2*s)) + 
         ((-cos(π/2*s) + 8im*t*(1+sin(π/2*s))/π)*(sin(π/4*s*sqrt(1+64*t^2/π^2))))/(sqrt(1+64*t^2/π^2))
         )/(2*sqrt(1+sin(π/2*s)))

test/simulate.jl

@@ -167,6 +167,23 @@ end
     end
 end
 
+@testset "analytic models, unitary check" begin
+    @testset "one qubit model" begin
+        s_vals = 0.0:0.5:1.0
+        for s in s_vals
+            ρ = one_spin_ρ(100.0, s=s)
+            @test tr(ρ) == 1
+        end
+    end
+
+    @testset "two qubit model" begin
+        s_vals = 0.0:0.5:1.0
+        for s in s_vals
+            ρ = two_spin_ρ(100.0, s=s)
+            @test tr(ρ) == 1
+        end
+    end
+end
 
 @testset "simulate, generic magnus expansion" begin
     @testset "1 qubit, adaptive, orders 1 to 8" begin
@@ -424,6 +441,11 @@ end
         @test isapprox(one_spin_ρ(1.0), ρ)
     end
 
+    @testset "1 qubit, function schedule, analytical solution with kwargs" begin
+        ρ = simulate_de(one_spin_model, 1.0, AS_CIRCULAR, 1e-6, saveat=[1])
+        @test isapprox(one_spin_ρ(1.0), ρ)
+    end
+
     @testset "2 qubit, function schedule, analytical solution" begin
         ρ = simulate_de(two_spin_model, 1.0, AS_CIRCULAR, 1e-6)
         @test isapprox(two_spin_ρ(1.0), ρ)