void quantum_delete_density_op( quantum_density_op *rho )
{
int i;
quantum_destroy_hash( rho->reg );
i = 0;
for ( ; i < rho->num; i++ )
{
quantum_delete_qureg_hashpreserve( &rho->reg[ i ] );
//i++;
}
free( rho->prob );
free( rho->reg );
quantum_memman( rho->num * -24 );
rho->prob = 0;
rho->reg = 0;
return;
}
void quantum_reduced_density_op( int pos, quantum_density_op *rho )
{
int i, j;
double p0 = 0.000000000000, ptmp;
unsigned long long pos2;
quantum_reg rtmp;
rho->prob = realloc( rho->prob, rho->num << 3 );
if ( rho->prob == 0 )
quantum_error( 2 );
rho->reg = realloc( rho->reg, rho->num * 40 );
if ( rho->reg == 0 )
quantum_error( 2 );
quantum_memman( rho->num * 24 );
pos2 = (long long)1 << pos;
i = 0;
for ( ; i < rho->num; i++ )
{
ptmp = rho->prob[ i ];
rtmp.width = rho->reg[ i ].width;
rtmp.size = rho->reg[ i ].size;
rtmp.hashw = rho->reg[ i ].hashw;
rtmp.node = rho->reg[ i ].node;
rtmp.hash = rho->reg[ i ].hash;
p0 = 0.000000000000;
j = 0;
for ( ; j < rho->reg[ i ].size; j++ )
{
if ( ( rho->reg[ i ].node[ j ].state & pos2 ) == 0 )
{
p0 += quantum_prob_inline( rho->reg[ i ].node[ j ].amplitude );
}
//j++;
}
rho->prob[ i ] = ptmp * p0;
rho->prob[ rho->num + i ] = ptmp * ( 1.000000000000 - p0 );
rho->reg[ i ] = quantum_state_collapse( pos, 0, rtmp );
rho->reg[ rho->num + i ] = quantum_state_collapse( pos, 1, rtmp );
quantum_delete_qureg_hashpreserve( &rtmp );
//i++;
}
rho->num <<= 1;
return;
}
int
quantum_bmeasure(int pos, quantum_reg *reg)
{
int i;
int result=0;
double pa=0, r;
MAX_UNSIGNED pos2;
quantum_reg out;
if(quantum_objcode_put(BMEASURE, pos))
return 0;
pos2 = (MAX_UNSIGNED) 1 << pos;
/* Sum up the probability for 0 being the result */
for(i=0; i<reg->size; i++)
{
if(!(reg->node[i].state & pos2))
pa += quantum_prob_inline(reg->node[i].amplitude);
}
/* Compare the probability for 0 with a random number and determine
the result of the measurement */
r = quantum_frand();
if (r > pa)
result = 1;
out = quantum_state_collapse(pos, result, *reg);
quantum_delete_qureg_hashpreserve(reg);
*reg = out;
return result;
}
int
quantum_bmeasure_bitpreserve(int pos, quantum_reg *reg)
{
int i, j;
int size=0, result=0;
double d=0, pa=0, r;
MAX_UNSIGNED pos2;
quantum_reg out;
if(quantum_objcode_put(BMEASURE_P, pos))
return 0;
pos2 = (MAX_UNSIGNED) 1 << pos;
/* Sum up the probability for 0 being the result */
for(i=0; i<reg->size; i++)
{
if(!(reg->node[i].state & pos2))
pa += quantum_prob_inline(reg->node[i].amplitude);
}
/* Compare the probability for 0 with a random number and determine
the result of the measurement */
r = quantum_frand();
if (r > pa)
result = 1;
/* Eradicate all amplitudes of base states which have been ruled out
by the measurement and get the absolute of the new register */
for(i=0;i<reg->size;i++)
{
if(reg->node[i].state & pos2)
{
if(!result)
reg->node[i].amplitude = 0;
else
{
d += quantum_prob_inline(reg->node[i].amplitude);
size++;
}
}
else
{
if(result)
reg->node[i].amplitude = 0;
else
{
d += quantum_prob_inline(reg->node[i].amplitude);
size++;
}
}
}
/* Build the new quantum register */
out.size = size;
out.node = calloc(size, sizeof(quantum_reg_node));
if(!out.node)
{
printf("Not enough memory for %i-sized qubit!\n", size);
exit(1);
}
quantum_memman(size * sizeof(quantum_reg_node));
out.hashw = reg->hashw;
out.hash = reg->hash;
out.width = reg->width;
/* Determine the numbers of the new base states and norm the quantum
register */
for(i=0, j=0; i<reg->size; i++)
{
if(reg->node[i].amplitude)
{
out.node[j].state = reg->node[i].state;
out.node[j].amplitude = reg->node[i].amplitude * 1 / (float) sqrt(d);
j++;
}
}
quantum_delete_qureg_hashpreserve(reg);
*reg = out;
return result;
}