public void Verify_Entangled_Electrons_Maintain_Entanglement()
{
Electron one = new Electron();
Electron two = new Electron();
int count_diff = 0;
int count_all = 0;
// measure them both on the X axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
// measure them both on the X axis - a bunch of times!
for (int j = 0; j < 1000; ++j)
{
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_X) != two.Spin(SPIN_AXIS.SPIN_AXIS_X))
{
++count_diff;
}
}
}
// measure them both on the Y axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
// measure them both on the Y axis - a bunch of times!
for (int j = 0; j < 1000; ++j)
{
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Y) != two.Spin(SPIN_AXIS.SPIN_AXIS_Y))
{
++count_diff;
}
}
}
// measure them both on the Z axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
// measure them both on the Z axis - a bunch of times!
for (int j = 0; j < 1000; ++j)
{
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Z) != two.Spin(SPIN_AXIS.SPIN_AXIS_Z))
{
++count_diff;
}
}
}
Assert.True(count_diff == count_all, "Must allways be anti-correlated.");
}
public void Verify_Randomized_Electrons_Not_Entangled()
{
Electron one = new Electron();
Electron two = new Electron();
int count_diff = 0; // we count anti-correlation
int count_all = 0;
// measure them both on the X axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.Randomize();
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_X) != two.Spin(SPIN_AXIS.SPIN_AXIS_X))
{
++count_diff;
}
}
// measure them both on the Y axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.Randomize();
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Y) != two.Spin(SPIN_AXIS.SPIN_AXIS_Y))
{
++count_diff;
}
}
// measure them both on the Z axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.Randomize();
++count_all;
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Z) != two.Spin(SPIN_AXIS.SPIN_AXIS_Z))
{
++count_diff;
}
}
Assert.False(count_diff == count_all, "Should not all be anti-correlated.");
}
public void Verify_Entangled_Electrons_Decohere()
{
Electron one = new Electron();
Electron two = new Electron();
int count_diff = 0;
int count_all = 0;
// measure them both on the X axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
++count_all;
bool measure_once = one.Spin(SPIN_AXIS.SPIN_AXIS_Z) != two.Spin(SPIN_AXIS.SPIN_AXIS_Z);
// measurement on Z should break entanglement on X
if (one.Spin(SPIN_AXIS.SPIN_AXIS_X) != two.Spin(SPIN_AXIS.SPIN_AXIS_X))
{
++count_diff;
}
}
// measure them both on the Y axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
++count_all;
bool measure_once = one.Spin(SPIN_AXIS.SPIN_AXIS_X) != two.Spin(SPIN_AXIS.SPIN_AXIS_X);
// measurement on X should break entanglement on Y
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Y) != two.Spin(SPIN_AXIS.SPIN_AXIS_Y))
{
++count_diff;
}
}
// measure them both on the Z axis
for (int i = 0; i < 1000; ++i)
{
one.Randomize();
two.EntangleSpins(one);
++count_all;
bool measure_once = one.Spin(SPIN_AXIS.SPIN_AXIS_Y) != two.Spin(SPIN_AXIS.SPIN_AXIS_Y);
// measurement on Y should break entanglement on Z
if (one.Spin(SPIN_AXIS.SPIN_AXIS_Z) != two.Spin(SPIN_AXIS.SPIN_AXIS_Z))
{
++count_diff;
}
}
Assert.False(count_diff == count_all, "Must not always be anti-correlated.");
}
/// <summary> Helper method to calculate correlation on chosen axes. </summary>
/// <param name="A"> The spin axis for Alice. </param>
/// <param name="B"> The spin axis for Bob. </param>
/// <param name="count"> The optional number of tests to run. Default 1000. </param>
public static double CorrelateElectronsOnAxes(SPIN_AXIS A, SPIN_AXIS B, int count = 1000)
{
Electron one = new Electron();
Electron two = new Electron();
double count_same = 0.0;
double count_diff = 0.0;
double count_all = 0.0;
for (int i = 0; i < count; ++i)
{
one.Randomize();
two.EntangleSpins(one);
int isA = one.Spin(A);
int isB = two.Spin(B);
count_all += 1.0;
if (isA == isB)
{
count_same += 1.0;
}
else
{
count_diff += 1.0;
}
}
// sadly, I forget where I saw this equation for calculating the correlation.
// usually it is more like:
//
// C = (num_pp + num_mm - num_pm - num_mp) / (num_pp + num_mm + num_pm + num_mp)
//
// but this is arithmetically equivalent. ( when strictly using real numbers. )
//
return((count_same - count_diff) / count_all);
}
/// <summary>
/// Run the three axes Bell Inequality Test against Sinnable Electrons.
/// </summary>
/// <remarks>
/// See https://en.wikipedia.org/wiki/Sakurai%27s_Bell_inequality
/// </remarks>
internal static void BellTriAxisElectronSpinTest()
{
SPIN_AXIS[] filters =
{
SPIN_AXIS.SPIN_AXIS_X,
SPIN_AXIS.SPIN_AXIS_Y,
SPIN_AXIS.SPIN_AXIS_Z
};
// every test works with two photons.
Electron one = new Electron();
Electron two = new Electron();
// various counts of the tests that pass the spin question.
int count_same = 0;
int count_same_XY = 0;
int count_same_YZ = 0;
int count_same_ZX = 0;
int count_all = 0;
int count_all_XY = 0;
int count_all_YZ = 0;
int count_all_ZX = 0;
for (int i = 0; i < 1000; ++i)
{
// force them to pick different filters
// X + Y, Y + Z, Z + X
int index_A = (i + 0) % 3;
int index_B = (i + 1) % 3;
SPIN_AXIS A = filters[index_A];
SPIN_AXIS B = filters[index_B];
// each test starts with a randomized particle
one.Randomize();
// and a particle in _perfect_ entanglement with it.
two.EntangleSpins(one);
int answer_A = one.Spin(A);
int answer_B = two.Spin(B);
count_all++;
// so we can know how many on each filter.
switch (index_A)
{
case 0: ++count_all_XY; break;
case 1: ++count_all_YZ; break;
case 2: ++count_all_ZX; break;
}
// count when they are in agreement.
if (answer_A == answer_B)
{
++count_same;
// and again, on each filter.
switch (index_A)
{
case 0: ++count_same_XY; break;
case 1: ++count_same_YZ; break;
case 2: ++count_same_ZX; break;
}
}
}
// correlation regardless of axes choice
double CE = (2.0 * count_same - count_all) / count_all;
// correlation on specific axes choice
double Cxy = (2.0 * count_same_XY - count_all_XY) / count_all_XY;
double Cyz = (2.0 * count_same_YZ - count_all_YZ) / count_all_YZ;
double Czx = (2.0 * count_same_ZX - count_all_ZX) / count_all_ZX;
// estimate of correlation combined.
double Ch = Cxy - Cyz - Czx;
bool spooky = (Ch >= 1.0);
Console.WriteLine(String.Format("Ce={0} Ch={1}, from {2} == {3}",
CE, Ch, count_all,
spooky ? "Spooky" : "Classic"));
}
