6 int readPaulicoeffs(int* alpha, int* beta, int* gamma, int* delta, int numqubits);
7 complex double Gausssum1d(int quadraticcoeff, int linearcoeff);
8 complex double Kroneck(int arg);
10 // order of matrix elements is [row][column]!!!
17 int N; // number of qubits
20 printf("Error: N must be a multiple of 3!\n");
24 int alpha[N], beta[N], gamma[N], delta[N];
26 double complex summand, sum;
28 while(readPaulicoeffs(alpha, beta, gamma, delta, N)) {
30 /* for(i=0; i<N; i++) */
31 /* printf("%d %d %d %d\n", alpha[i], beta[i], gamma[i], delta[i]); */
37 //for(x=0;x<=(y*(gamma[i]+gamma[i+1])+(y+1)*(gamma[i]+delta[i+1]))%2; x++) {
38 for(x=y*(beta[i]+alpha[i+1]+beta[i+1])%2;x<=(y*(beta[i]+alpha[i+1]+beta[i+1])+y*(gamma[i]+gamma[i+1])+(y+1)*(gamma[i]+delta[i+1]))%2; x++) {
39 summand += 0.125*pow(2.0,1-y*pow(gamma[i]-gamma[i+1],2)-pow(y-1,2)*pow(gamma[i]-delta[i+1],2))*cexp(M_PI*I/2.0*((delta[i+1]-gamma[i])*pow(y+1,2)+2.0*(beta[i]+beta[i+1]+gamma[i]+delta[i+1])*x*pow(y+1,2)+2.0*(delta[i]+delta[i+1]+beta[i]+beta[i+1])*x*y+(2.0*beta[i]+3.0*delta[i]+delta[i+1])*y))*Gausssum1d(0.0,beta[i+2])*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1])*Kroneck(gamma[i+2]+delta[i+2]);
40 summand += 0.125*pow(2.0,1-y*pow(gamma[i]-gamma[i+1],2)-pow(y-1,2)*pow(gamma[i]-delta[i+1],2))*cexp(M_PI*I/2.0*((delta[i+1]-gamma[i])*pow(y+1,2)+2.0*(beta[i]+beta[i+1]+gamma[i]+delta[i+1])*x*pow(y+1,2)+2.0*(delta[i]+delta[i+1]+beta[i]+beta[i+1])*x*y+(2.0*beta[i]+3.0*delta[i]+delta[i+1])*y))*csqrt(-I)*Gausssum1d(gamma[i+2]+delta[i+2],0)*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1])*Kroneck(alpha[i+2]+beta[i+2]);
41 //summand += 0.125*pow(2.0,gamma[i]+delta[i]+x*y*(beta[i]+alpha[i])*alpha[i+1]+pow(x-1,2)*y*(alpha[i]+beta[i])*beta[i+1]-y*pow(gamma[i]-gamma[i+1],2)-pow(y-1,2)*pow(gamma[i]-delta[i+1],2))*cexp(M_PI*I/2.0*((delta[i+1]-gamma[i])*pow(y+1,2)+2.0*(beta[i]+beta[i+1]+gamma[i]+delta[i+1])*x*pow(y+1,2)+2.0*(delta[i]+delta[i+1]+beta[i]+beta[i+1])*x*y+(2.0*beta[i]+3.0*delta[i]+delta[i+1])*y))*Gausssum1d(0.0,beta[i+2])*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1])*Kroneck(gamma[i+2]+delta[i+2]);
43 //for(x=((y+1)*(alpha[i]+beta[i]))%2;x<=((beta[i]+alpha[i])+y*(gamma[i]+gamma[i+1])+(y+1)*(gamma[i]+delta[i+1]))%2; x++) {
44 //summand += 0.125*pow(2.0,gamma[i]+delta[i]+x*y*(beta[i]+alpha[i])*alpha[i+1]+pow(x-1,2)*y*(alpha[i]+beta[i])*beta[i+1]-y*pow(gamma[i]-gamma[i+1],2)-pow(y-1,2)*pow(gamma[i]-delta[i+1],2))*cexp(M_PI*I/2.0*((delta[i+1]-gamma[i])*pow(y+1,2)+2.0*(beta[i]+beta[i+1]+gamma[i]+delta[i+1])*x*pow(y+1,2)+2.0*(delta[i]+delta[i+1]+beta[i]+beta[i+1])*x*y+(2.0*beta[i]+3.0*delta[i]+delta[i+1])*y))*csqrt(-I)*Gausssum1d(gamma[i+2]+delta[i+2],0)*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1])*Kroneck(alpha[i+2]+beta[i+2]);
47 for(y=0; y<=(1+alpha[i+2])%2; y++) {
48 for(x=0;x<=(1+beta[i+2])%2; x++) {
49 summand += 0.125*2.0*csqrt(-I)*cexp(M_PI*I/2.0*(2.0*beta[i+2]*y+pow(x+1,2)*(delta[i]+gamma[i+1]+2.0*beta[i+1])+x*(delta[i]+delta[i+1])))*Gausssum1d(1,beta[i]+beta[i+1]+delta[i]+(x+1)*gamma[i+1]+x*delta[i+1])*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1]+1)*Kroneck(gamma[i+2]+delta[i+2]);
53 for(x=(y*(delta[i]+delta[i+1]))%2;x<=(1+y*(gamma[i]+gamma[i+1]))%2; x++) {
54 summand += 0.125*pow(2.0,pow(y-1,2)*(pow(x,2)*(gamma[i]+delta[i+1])+pow(x-1,2)*(gamma[i+1]+delta[i])))*(-I)*cexp(M_PI*I/2.0*(y*(delta[i]+delta[i+1])+pow(y+1,2)*(delta[i]+gamma[i+1]+2*beta[i+1])+pow(x,2)+2*(beta[i]+beta[i+1]+delta[i]+gamma[i+1]*(y+1)+delta[i+1]*y)*x))*Gausssum1d(0,x+beta[i]+beta[i+1]+delta[i]+gamma[i+1]*(y+1)+delta[i+1]*y+gamma[i+2]+delta[i+2])*Kroneck(gamma[i]+delta[i]-gamma[i+1]-delta[i+1]+1)*Kroneck(alpha[i+2]+beta[i+2]);
59 //printf("%lf+%lfI\n", creal(sum), cimag(sum));
60 printf("%lf\n", cabs(creal(sum)));
68 complex double Kroneck(int arg)
70 arg = (arg+1)%2; // output 1 if argument is 0 mod 2 and 0 otherwise
71 return ((complex double)arg);
74 complex double Gausssum1d(int quadraticcoeff, int linearcoeff)
76 /*****************************************
77 /* NOTE! we assume coeffs are either 0 or 1
78 /* (So you cannot pass off a linear coeff as a quadratic coeff by multiplying it by a factor of 2 (and considering it as mod 4)!)
79 *****************************************/
84 if(quadraticcoeff == 0)
97 int readPaulicoeffs(int *alpha, int *beta, int *gamma, int *delta, int numqubits)
102 if(scanf("%d %d %d %d", &alpha[0], &beta[0], &gamma[0], &delta[0]) != EOF) {
103 for(i=1; i<numqubits; i++) {
104 scanf("%d %d %d %d", &alpha[i], &beta[i], &gamma[i], &delta[i]);