Computing Partition Functions on Limited Quantum Devices

We showcase an algorithm for approximating partition functions at (potentially) complex inverse temperatures. Compared to other partition function approximation algorithms, it is better suited for execution on near term devices due to significant reductions in the circuit depth, required number of qubits, and/or required number of measurements. All of which reduce the effect of noise on the computation. The key improvement is that the depth of the circuits required is independent of the real component of inverse temperature, hence low temperature physics (which for a strongly-correlated system is classically much harder to study) are more accessible and can tolerate a greater error rate.