If a local density operator is expressed by (ho(r)=sum_{i} deltaleft(r-r_{i} ight)), where the sum is over particles

If a local density operator is expressed by \(ho(r)=\sum_{i} \delta\left(r-r_{i}\right)\), where the sum is over particles and \(\delta\left(r-r_{i}\right)\) is the Dirac delta function, what is its second-quantized form?