/// <summary>
/// The probabilities of each possible register value indexed by that value.
/// </summary>
public static double[] GetDistribution(this IQuantumState state, Register reg)
{
int regSize = reg.QubitIndexes.Count();
long maxRegValue = (long)Math.Pow(2, regSize);
// probabilities indexed by register value
double[] regProbabilities = new double[maxRegValue];
// go through every probability
for (long i = 0; i < state.Dimension; i++)
{
var basis = new ComputationalBasis(i, state.NumQubits());
var amp = state.GetAmplitude(basis);
if (amp.Magnitude < ComplexExt.Precision)
{
continue;
}
var labels = basis.GetLabels();
var registerLabels = new List <bool>();
foreach (var index in reg.QubitIndexes)
{
registerLabels.Add(labels[index]);
}
long regValue = ComputationalBasis.FromLabels(registerLabels.ToArray()).AmpIndex;
regProbabilities[regValue] += amp.Magnitude * amp.Magnitude;
}
return(regProbabilities);
}
public static string Print(this IQuantumState state, params Register[] registers)
{
var test = state.ToArray().Where(b => b.Magnitude > ComplexExt.Precision);
StringBuilder sb = new StringBuilder();
for (long i = 0; i < state.Dimension; i++)
{
var basis = new ComputationalBasis(i, state.NumQubits());
var amp = state.GetAmplitude(basis);
if (amp.Magnitude < ComplexExt.Precision)
{
continue;
}
sb.Append($"+{(amp.Imaginary == 0 ? amp.Real.ToString("F2") : amp.ToString("F2"))}");
var labels = basis.GetLabels();
foreach (var register in registers)
{
var registerLabels = new List <bool>();
foreach (var index in register.QubitIndexes)
{
registerLabels.Add(labels[index]);
}
long regValue = ComputationalBasis.FromLabels(registerLabels.ToArray()).AmpIndex;
sb.Append($"|{regValue}>");
}
}
return(sb.ToString());
}
public static string Print(this IQuantumState state) => state.Print(
Enumerable.Range(0, state.NumQubits())
.Select(i => new Register
{
QubitIndexes = new[] { i }
}).ToArray());
