The calculation of imaginary time displaced correlation functions with the auxiliary field projector quantum MonteCarlo algorithm provides valuable insight (such as spin and charge gaps) in the model under consideration. One of the authors and M. Imada [1] have proposed a numerically stable method to compute those quantities. Although precise this method is expensive in CPU time. Here, we present an alternative approach which is an order of magnitude quicker, just as precise, and very simple to implement. The method is based on the observation that for a given auxiliary field the equal time Green function matrix, G, is a projector: PACS numbers: 71.27.+a, 71.10.Fd For a given Hamiltonian H = x,y c † x T x,y c y + H I and its ground state |Ψ 0 , our aim is to calculateHere, c † x creates an electron with quantum numbers x, c x (τ ) = e τ (H−µN ) c x e −τ (H−µN ) , and the chemical poten-H I corresponds to the interaction. Within the projector Quantum Monte Carlo (PQMC) algorithm, this quantity is obtained by propagating a trial wave |Ψ T function along the imaginary time axis [2-4]:The above is valid provided that: Ψ 0 |Ψ T = 0.To fix the notation, we will briefly summarize the essential steps required for the calculation of the right hand side (rhs) of the above equation at fixed values of the projection parameter Θ. A detailed review may be found in [5]. The formalism -without numerical stabilization -to compute time displaced correlation functions follows Ref.[6]. The first step is to carry out a Trotter decomposition of the imaginary time propagation: e −2ΘH = e −∆τ Ht/2 e −∆τ HI e −∆τ Ht/2 m + O((∆τ ) 2 ).Here, H t (H I ) denotes the kinetic (interaction) term of the model and m∆τ = 2Θ. Having isolated the interaction term, H I , one may carry out a Hubbard Stratonovitch (HS) transformation to obtain:where s denotes a vector of HS fields. For a Hubbard interaction, one can for example use various forms of Hirsch's discrete HS decomposition [7,8]. For interactions taking the form of a perfect square, decompositions presented in [9] are useful. The imaginary time propagation may now be written as:e −∆τ Ht/2 e x,y c † x Dx,y( sn)cy e −∆τ Ht/2 .The HS field has acquired an additional imaginary time index since we need independent fields for each time increment.The trial wave function is required to be a Slater determinant:Here N p denotes the number of particles and P is an N s × N p rectangular matrix where N s is the number of single particle states. Since U s (2Θ, 0) describes the propagation of non-interacting electrons in an external HS field, one may integrate out the fermionic degrees of freedom to obtain:where we have omitted the (∆τ ) 2 systematic error produced by the Trotter decomposition. In the above equation,