This paper presents a method for efficiently preparing high-temperature quantum Gibbs states and their purifications using quantum Gibbs samplers. The approach involves a dissipative evolution that thermalizes to the Gibbs state in time polynomial in system size at high temperatures, and for Hamiltonians satisfying a Lieb-Robinson bound, such as local Hamiltonians on a lattice. The method also enables efficient adiabatic preparation of thermofield double states, which are purifications of Gibbs states. In the low-temperature regime, the method is shown to be polynomially equivalent to standard quantum computation. The results demonstrate that a family of quasi-local dissipative evolutions can efficiently prepare a large class of quantum many-body states, with potential applications in quantum simulation and quantum computing. The work establishes the first rigorous results on the efficient preparation of high-temperature Gibbs states and their purifications, and shows that the algorithm can simulate quantum circuits at low temperatures with a polynomial overhead. The paper also compares the results with previous work and highlights the significance of the findings for quantum computing and simulation.This paper presents a method for efficiently preparing high-temperature quantum Gibbs states and their purifications using quantum Gibbs samplers. The approach involves a dissipative evolution that thermalizes to the Gibbs state in time polynomial in system size at high temperatures, and for Hamiltonians satisfying a Lieb-Robinson bound, such as local Hamiltonians on a lattice. The method also enables efficient adiabatic preparation of thermofield double states, which are purifications of Gibbs states. In the low-temperature regime, the method is shown to be polynomially equivalent to standard quantum computation. The results demonstrate that a family of quasi-local dissipative evolutions can efficiently prepare a large class of quantum many-body states, with potential applications in quantum simulation and quantum computing. The work establishes the first rigorous results on the efficient preparation of high-temperature Gibbs states and their purifications, and shows that the algorithm can simulate quantum circuits at low temperatures with a polynomial overhead. The paper also compares the results with previous work and highlights the significance of the findings for quantum computing and simulation.